Gary Paul Nabhan, PhD., Agroecologist, Borderlands Restoration Network
When most Americans think of crop production, they tend to imagine crops growing in full sunlight to achieve their full potential for productivity. But over decades,there has always been crop production in shade habitats or constructed environments, as well. Indeed, much of the coffee and chocolate (cocoa) consumed as beverages has been grown under shade-bearing, nitrogen-fixing legume trees such as madrecacao (Glyericidia sepia), a tropical tree with a dense and expansive canopy that protects understory crops from excessive heat and damaging radiation.
Virtually all the food crops, forages, and medicinal herbs grown in North American agroforestry and alley-cropping systems are to some extent shade-tolerant. Many—like chile peppers—can comfortably tolerate a 35% to 50% reduction in photosynthetically active radiation (PAR) compared to open sunlight all day. They seldom suffer a yield reduction due to less sunlight in this range, especially from noon to 4 p.m. Iin fact, yields in some varieties are augmented, perhaps because a significant percentage of all arid, temperate, and tropical wild plants evolved to begin their lives under the shade of “nurse plants” and have evolved shade tolerance to varying degrees over millennia. More than 30,000 farmers in the U.S. were engaging in one or more types of agroforestry practices by 2017, when agrivoltaic practices first hit the American scene.
Agrivoltaic pepper plants in Arizona. Photo: NCAT
Benefits and Challenges of Solar and Crop Co-Location
So, what kind of benefits do shade-grown crops receive, and what are the challenges of growing crops under any kind of shade, for both the trees and the solar panels?
Benefits
Let’s first look at the benefits. Shade reduces the amount of sunburn or sun scald that understory plants receive but particularly reduces the effects of damaging ultraviolet radiation. It also serves as a temperature buffer, reducing high summer temperatures by as much as 4°F to 6°F and keeping winter temperatures in crop canopies 2°F to 4°F warmer—in some cases, enough to avert premature freezes or to extend the frost-free growing season by as much as three weeks. With less direct sun, evaporation of water from the soil and transpiration from the leaves are reduced, and soil moisture stress may not be as severe.
The flowers of crops abort less in cooler temperatures, and they also attract more pollinators. Plant desiccation is not only reduced, but the nitrogen content of the foliage also does not spike enough to trigger feeding frenzies by leaf-sucking or browsing insects. At the same time, the Brix levels—an indicator of how sweet and nutritious vegetables and herbs might be—is sustained at higher levels, adding to the value of the crop.
Perhaps the ultimate advantage is that it buffers farmworkers managing or harvesting from severe heat stress and dehydration in hot summers, improving their harvesting efficiency and reducing their vulnerability to hazards and illness. In 2023 alone, 30,000 more outdoor workers in the U.S. succumbed to heat stress than in any other year in recorded history. Since hand-harvested crops are time-consuming, their harvesters are especially vulnerable.
Thermal image showing farm worker under a solar panel with a body temperature of 80°F and an outdoor temperature over 100°F. Photo: NCAT
Challenges
The disadvantages of co-location are more obvious for some sun-loving plants than for others. If the canopy tree or solar panel “competes” for too much light, it will result in reductions in photosynthesis and yields, thereby impeding the growth of the underling. However, there may be more humidity retained in the under-panel microclimate that fosters fungal diseases and possibly leads to more plant damage from insects that thrive on the fungal environment.
Crop height may be impeded, requiring more pruning or difficulty in harvesting. And of course, most mechanical harvesters of high stature are eliminated from use if panel are 5 meters (16.4 feet) or less in height.
Lastly, the space under photovoltaic panels is economically and ecologically costly per square meter; the metal, copper wiring and glass or plastic fiber glazing in photovoltaic panels is burdened with considerable “embedded energy” within it, so each panel provides small but very expensive growing space (except when compared to high-tech, computerized greenhouses with air conditioning and movable benches.) It is unlikely that growing grains or dry beans under photovoltaic arrays will ever be cost-effective.
So, what is different and distinctive about the shaded growing spaces under photovoltaic panels? For one thing, these areas have solid or slotted covers, rather than being diffused and porous like most leafy canopies. Secondly, all constructed spaces in a photovoltaic array are of similar height and size, whereas the height and size(s) are highly variable in natural or semi-managed forests.
In natural settings, “nurse trees” also offer much more than shade and temperature buffering to understory plants; they also offer mycorrhizal connections and soil fertility renewal. Some deep-rooted legume trees also pump and leak water and nutrients to other plants in their nurse plant guild that are too young to do this on their own
The crops discussed here that are most suitable for agrivoltaics conditions are high-value cash crops or nutritionally dense fruits and vegetables for home or community consumption. These crops are more suitable for agrivoltaics conditions compared to grain or bean crops, for example. Medicinals and pharmafood crops would likely be a better fit for growing conditions that are produced from dual-use land environments.
Agrivoltaic pepper plants in Arizona. Photo: AgriSolar Clearinghouse
Considerations for Crop Selection
It is important to consider what shape, size, and habit of crop plants might be most appropriate for agrivoltaics production over an extended period of time. When considering crops that will be well-suited for the conditions of an agrivoltaics site, it is important to consider the following points.
Crop Characteristics:
Vining or “bush” growth forms
Sun-loving or shade-loving
Height and width of fully grown plant
Multiple harvests or single harvests required?
Root depth
If we were to design an “ideotype” best suited to the photovoltaic micro-environment, it would need to meet at least five of the following plant characteristics:
Vertically-vining or “indeterminate” growth forms that make maximum use of the space under solar panels by being trellised or “stiffer” scandent plants that lean upon a trellis (such as dragon fruit and capers). Vining plants that spread out beyond the perimeters of the panels may have a cooling effect that increases photovoltaic energy production efficiency (his strategy assumes that the interspaces between panels are not being utilized in another way).
Tolerate moderate (especially mid-day) shade, with interception or screening of photosynthetically active radiation (PAR) in the range from 35 to 50% of total daylight,
Growth habit that will allow for harvesting of seed, fruit, flowers, floral buds, or leaves from waist high (1 meter or 3.28 feet) to shoulder-high (1.4 to 1.8 meters or 4.59 to 5.9 feet) above the ground to allow work by hand or mechanical harvesters.
Can be harvested or “cut” multiple times per season, pruning them to stimulate subsequent regrowth and recutting within three to four weeks of the previous harvest.
Be either deep-rooted or shallow-rhizomatous perennials with runners, or longer-lived seasonal annuals that can be uprooted after the last harvest to allow new transplants to go into the same space.
Now that we’ve established the ideal architectural and behavioral criteria for selecting crop plants, here is a list of crops that meet three or more of these criteria. These lists emphasize high-value crop plants that have other adaptations to hot, dry conditions but may require partial shade or frequent cutting and harvesting.
Berry vines and bushes with long, arching shoots that can be both vertically and horizontally trellised: currants, dewberries, gooseberries (Ribes spp.);brambleberries, blackberries, dewberries, and loganberries (Ribes spp.), grapes, including muscadines, musquats, scuppernongs, etc. (Vitis spp.)
Arborescent and scandent cacti with high-value fruit: cochineal nopal (Opuntia cochiillifera) dragonfruit cacti, including white-fleshed pitahaya (Selinicereus undulatus), red-fleshed pitahaya (Selenicereus costaricensis), and yellow pitahaya (Selenicereus megalanthus); pitahaya agrias (Stenocereus gummosus, S. quereteroensis, and S. griseus), longer-lived seasonal annuals that can be pulled up after the last harvest to allow new transplants to go into the same space.
Short-stature shrubs with copious production of fruits, buds, or berries over a long season: capers (Capparisspinosa); capulín sand cherries (Prunus salicifolia); chiltepín, chile del arbol, shishito, etc. (Capsicum annuum); Mexican hawthorn or tejocote (Crataegus mexicana); elderberry (Sambucus nigra); goji or wolfberry (Lycium barbarum, L. chinense, L. fremontii, and L. pallidum); Persian lime (Citrus x latifolia); key lime (Citrus aurantifolia); kumquat (Fortunella margarita and hybrids); jujube (Zizyphus jujba); guava (Psidium guajava); hibiscus or Jamaican sorrel (Hibiscus sabdardiff); ormaypops and passion fruit (Passiflora spp.).
Perennial culinary herbs that can tolerate (or increase production with) frequent, severe cuttings: Mexican oregano (Lippia berlandieri, L. graveolens), saffron (Crocus sativus), Mexican tarragon (Tagetes lucida), papaloquelite (Porophyllum ruderale) Sierra Madre oregano (Poliomentha madrensis), lavandin (Lavendula intermedia), Greek oregano (Origanum vulgare), thyme (Thymus vulgaris), and lemongrass (Cymbopogon citratus).
Dwarf or drastically pruned trees with high-value fruit: dwarf varieties of figs (Ficus spp.), pomegranates (Punica granatum), cherries, including the Mahaleb cherry (Prunus mahaleb), olive (Olea europea), Sechuan peppers (Zanthoxylum armatum, Z. bungeanum, and Z. simulans), and Mediterranean sumac (Rhus coriaria).
Long-season annual herbs or perennial pharmafoods (nutriceuticals) that can tolerate frequent cuttings: sweetleaf stevia (Stevia rebaudiana), holy basil or tulsi (Ocimum tenuiflorum), damiana (Turnera diffusa), saffron (Crocus sativus), wild Lebanese cucumber-melon (Cucumis melo, a parent of the popular beit-alpha greenhouse cucumber); and chia (Salvia hispanica).
It is important to consider what horticultural design and density qualifies as having the optimal features required to grow in agrivoltaics conditions, for none of these proposed crops need to be grown in evenly spaced monoculture. For instance, the least sun-sensitive crop varieties can go on the periphery of the solar panels, preserving the core area for the most shade-tolerant varieties or species.
A Speaker Discusses Agrivoltaics in Arizona. Photo: AgriSolar Clearinghouse
Alternatively, taller woody perennials can be placed under the highest levels of the panels, with the shorter varieties or species reserved for the shortest area toward the “front” of the angled panel. However, new designs of photovoltaics have computerized solar trackers for mobile or reclinable units, so that may become an irrelevant consideration in the future. Another option is to grow indeterminate vine crops such as cucumbers or grapes on the periphery of the solar panel shadow. This might allow those crops to “crawl out,” and provide greenery that reduces ambient temperatures on the panel surface. This may increase daily energy production efficiency and extend the lifetime of the panel(s).
A final consideration is that for extremely high-value crops like pharmafoods and pharmaceuticals, screening the sides of the growing space may reduce or halt predation by insects or vertebrate herbivores. The overall cost of construction and production in an agrivoltaic system would remain far less than that for most commercial greenhouses, but the agrivoltaic micro-climate and growing space would then be considered a “controlled environment.”
When selecting crops that are uniquely suited to be grown in agrivoltaic settings, consider the guidance provided above. Ask questions related to the features of the solar panel design, including height, width, and other design features, as well as measurements. Then, consider the plant characteristics that are being considered for that site: height, width, water consumption, root depth, harvesting schedule, etc. Next, form a strategy from the characteristics you have identified for both the panels and the plants and make an informed decision about what will work best for that specific agrivoltaic site, as agrivoltaics conditions can vary from one site to another.
https://www.agrisolarclearinghouse.org/wp-content/uploads/2024/10/image-7.jpeg1349899A. J. Pucketthttps://www.agrisolarclearinghouse.org/wp-content/uploads/2022/02/AgriSolar_stacked_1-338x400.pngA. J. Puckett2024-10-17 10:40:062024-10-17 10:47:23Crops Uniquely Suited to Growth in Agrivoltaic Settings
Leroy J. Walston, Heidi Hartmann, Laura Fox, Michael Ricketts, Ben Campbell, and Indraneel Bhandari, Argonne National Laboratory
This section highlights several types of agrivoltaic options related to ecosystem services that include siting considerations, ecological impacts of dual-use sites, construction methods and habitat restoration strategies. One type focuses on ecologically focused siting, construction, and vegetation management principles in an effort to make photovoltaic (PV) solar energy more ecologically compatible. This includes minimizing ecological impacts associated with siting and construction and improving the ecological value of the site through habitat enhancement. Given its ecological focus, this form of agrivoltaics design is often referred to as ecovoltaics (Sturchio and Knapp, 2023; Tölgyesi et al., 2023).
The co-location of solar energy and habitat restoration (i.e., habitat-friendly solar‘ or solar-pollinator habitat) has become the most popular ecovoltaics strategy to safeguard biodiversity and improve the site’s ecosystem services output. Habitat-friendly solar designs typically focus on the planting and establishment of deep-rooted and regionally appropriate native grasses, wildflowers, and other non-invasive naturalized flowering plant species. The habitat created at these sites could support insect pollinators and other wildlife and improve other ecosystem services of the site (Figure 1).
But what ecosystem service benefits might be realized at solar facilities managed for habitat? Agrivoltaics can broadly improve the output of all classes of ecosystem services (Figure 2). Conceptually, solar-pollinator habitat has the potential to improve the outputs of all classes of ecosystem services (Table 1).
The pairing of solar energy and habitat enhancement sounds like a logical win-win for clean energy and biodiversity. However, several factors can influence the feasibility and ecological effectiveness of solar-pollinator habitat, such as geography, seed availability and cost, previous land use, soil type, and solar size and design (e.g., PV panel height and spacing). Several scientific studies have been conducted in recent years to examine different solar-pollinator habitat configurations and management options. Two studies in particular are the Innovative Solar Practices Integrated with Rural Economies and Ecosystems (InSPIRE; openei.org/wiki/InSPIREopenei.org/wiki/InSPIRE) and Pollinator Habitat Aligned with Solar Energy (PHASE; rightofway.erc.uic.edu/phase). Both projects are funded by the U.S. Department of Energy (DOE) Solar Energy Technologies Office (SETO) and include a focus on the ecological and economic implications of solar-pollinator habitat. Results from these studies have shed light on which vegetation establishes at solar sites based on their unique management needs and the amount of time required for vegetation to establish and for biodiversity responses to be measured. These studies incorporate the research findings intoguidelines and toolkits to assist the site-specific selection of seed mixes and management strategies to optimize the performance of solar-pollinator habitat based on ecological and economic (budget) objectives.
Figure 1. A) Illustration of the theoretical ecosystem services of solar-pollinator habitat. Compared to conventional groundcover, such as turfgrass, solar-pollinator habitat can provide higher-quality habitat for biodiversity. B) Example image of solar-pollinator habitat at a solar site in Minnesota. Images: Argonne National Laboratory
Table 1. Potential Ecosystem Services of Solar-Pollinator Habitat.
Ecosystem Service
Benefit
Biodiversity conservation (broadly linked to all ecosystem service classes)
Solar-pollinator habitat can safeguard biodiversity by supporting a larger diversity of organisms and communities. This could benefit several ecosystem services, such as food production (provisioning), recreation (cultural), water conservation (regulating), and nutrient cycling (supporting) (Walston et al., 2021, 2022, 2024; Blaydes et al., 2024).
Energy production (provisioning service)
Solar-pollinator vegetation can create favorable microclimates to improve PV panel performance (Choi et al., 2023).
Food production (provisioning service)
Solar-pollinator habitat can improve populations of insect pollinators and predators, which can benefit nearby agricultural production (Walston et al., 2024).
Carbon sequestration and soil health (regulating services)
The establishment of solar-pollinator habitat typically involves soil and vegetation management practices that allow for greater soil carbon sequestration over time, compared to other land uses (Walston et al., 2021).
Stormwater and erosion control (regulating service)
Deep-rooted solar-pollinator habitat can help stabilize soil and minimize runoff (Walston et al., 2021).
Nutrient cycling and air quality (supporting services)
Solar-pollinator habitat can improve nutrient cycling and air quality (Wratten et al. 2012; Agostini et al., 2021).
Aesthetics and recreation (cultural services)
Solar-pollinator habitat can improve human perception public acceptance of the solar site (Moore et al., 2021).
What are best practices for establishing solar-pollinator habitat?
There is growing science-based evidence on the ecological effectiveness of solar-pollinator habitat. Most of this research focuses on two main aspects: 1) vegetation establishment and management; and 2) biodiversity responses (Figure 2). One critical need for the solar industry has been assistance in selecting the seed mix design and vegetation management tools that would optimize the establishment of solar-pollinator habitat for a site’s specific physical characteristics (e.g., geographic region, soil type), PV site design (e.g., plant height restrictions), and budget. To help guide these decisions, the DOE PHASE project has produced a series of tools to inform solar-pollinator habitat planting implementation, seed selection, cost comparisons, and habitat assessment (Figure 3).
What do we know about the effectiveness of solar-pollinator habitat?
This section highlights objectives and outcomes from field research projects funded by DOE to understand the ecosystem services of solar-pollinator habitat. Two case studies are presented: 1) potential biodiversity benefits of solar-pollinator habitat; and 2) potential benefits of solar-pollinator habitat for soil health.
Case Study 1: If You Build It, They Will Come
A recent study from the DOE InSPIRE project examined the biodiversity responses for five years following the establishment of solar-pollinator habitat (Walston et al., 2024). The research was conducted at two Minnesota PV solar facilities owned and operated by Enel Green Power. The research team from Argonne National Laboratory, National Renewable Energy Laboratory, and Minnesota Native Landscapes conducted a longitudinal field study over five years (2018 to 2022) to understand how insect communities responded to newly established habitat on solar energy facilities in agricultural landscapes. Specifically, they investigated: 1) temporal changes in flowering plant abundance and diversity; 2) temporal changes in insect abundance and diversity; and 3) pollination services of solar-pollinator habitat to nearby agricultural fields. The team found increases over time for all habitat and biodiversity metrics. For example, by 2022, the researchers observed a sevenfold increase in flowering plant species richness, and native abundance increased by over 20 times the numbers initially observed in 2018 (Figure 4). The research team also found positive effects of proximity to solar-pollinator habitat on bee visitation to nearby soybean (Glycine max) fields. Bee visitation to soybean flowers adjacent to solar-pollinator habitat were greater than bee visitation to soybean field interior and roadside soybean flowers (Figure 5). These observations highlight the relatively rapid (less than four years) insect community responses to solar-pollinator habitat. This study also demonstrates that, if properly sited and managed, solar-pollinator habitat can be a feasible way to safeguard biodiversity and increase food security in agricultural landscapes. Photos of solar-pollinator habitat insects visiting the on-site vegetation at these sites are shown in Figure 6.
Figure 4. Observed and predicted measures of (A) flowering plant species richness and (B) native bee abundance recorded over time at two PV solar facilities planted with pollinator-friendly habitat in Minnesota. (Walston et al., 2024).
Figure 5. Observed bee visitation to soybean flowers at different field locations in Minnesota. Different letters indicate statistically different groups at the p = 0.05 level (Walston et al., 2024).
Figure 6. Solar-pollinator habitat and insects observed at solar facilities in Minnesota. Top: solar-pollinator habitat dominated by purple prairie clover and black-eyed Susan flowers, with a honeybee visiting a flower (inset). Bottom: solar-pollinator habitat dominated by yellow coneflower. Photos: Argonne National Laboratory
Case Study 2: Soil Health Benefits of Solar-Pollinator Habitat
As PV solar energy sites become increasingly common, there is growing interest in identifying potential co-benefits, in addition to energy production, that could be provided using the same land area (Choi et al., 2023). These co-benefits include a variety of both economic and ecosystem services, many of which rely greatly on preserving, restoring, and/or maintaining a healthy soil environment, which is itself a valuable ecosystem service. Healthy soils are key to supporting and nurturing plant growth, and solar facilities offer a unique opportunity to improve soils that are either naturally low-quality or have been degraded from decades of agriculture. This can be accomplished through a variety of strategic planning initiatives and land management practices that focus on minimizing soil and vegetation disturbances and encouraging the establishment of ecologically friendly and sustainable ecosystems. By understanding the relationships and interactions that exist between plants and the soil environment, wecan gain valuable insights into how to maximize land-use efficiency and increase sustainable land management practices over the large areas of land that will be required for utility-scale solar facility development needed to achieve the renewable energy goals of the United States by 2050.
Just as healthy soil is necessary to support plant growth, plants can help improve soil health through various mechanisms (Figure 7). Soil health is characterized by a combination of physical, chemical, and biological properties, including bulk soil density, water infiltration and holding capacity, soil organic carbon and available nutrient contents, soil pH and cation exchange capacity, and microbial activity and diversity. Plant roots, especially those from deep-rooting perennial species (such as are found in many pollinator seed mixes), help reduce soil erosion and improve soil structure by providing a supportive network of course and fine roots that stabilize soil particles and aggregates while simultaneously improving water infiltration. Plants also supply organic matter, carbon, and other nutrients to the soil environment viasurface leaf litter, root exudates, and root litter. These organic matter inputs serve as nutrient pools for micro- and macro-organisms in the soil, and to increase soil water-holding capacity. Additionally, a portion of the carbon from plant organic matter inputs and microbial necromass will end up becoming associated with soil minerals to form mineral-associated organic matter (MAOM), which can have very long residence times in soil and serve as a carbon sink for atmospheric CO2 (Bai and Cotrufo, 2022).
There are many ways that vegetation can be used at solar facility sites to provide additional benefits beyond increasing soil health. While there is much research that has shown the positive effects of vegetation on soil health, research that specifically addresses how soil health indicators are affected by land management practices at solar facilities is lacking. Given what is known, it is reasonable to expect that sustainable vegetation management at solar facilities will result in improved soil health over time. However, this is likely dependent on the degree of disturbance sustained during site construction, and possibly any number of other controlling factors, such as local climate, native vegetation, and/or soil type. For example, Choi et al. (2020) found that even after seven years of revegetation at a solar facility site in Colorado, carbon and nitrogen concentrations had not recovered to comparable levels of adjacent reference grasslands. The authors attributed this to the significant amount of topsoil removal and grading that occurred during site construction, which significantly disturbed and mixed the soil profile, resulting in severely reduced surface carbon and nitrogen levels. However, this study did not compare vegetated areas to non-vegetated areas within the site. Another study by Choi et al. (2023) did make this comparison at a site in Minnesota where topsoil removal and grading were avoided. The researchers found that revegetated areas had significantly more carbon, nitrogen, and other nutrients levels relative to the areas that were left bare and were ultimately similar to adjacent control plots (Figure 8). This disparity in results and lack of clear data presents a challenge to understanding soil health dynamics as it relates to land management practices at solar facilities.
Fortunately, DOE SETO has sponsored a project whose sole focus is to gather soil data from solar facilities across a wide range of environments in the United States that can hopefully address this question. This project, Ground-mounted Solar and Soil Ecosystem Services, is being led by Argonne National Laboratory and will provide standardized guidance on measuring and analyzing soil parameters central to soil health at solar facilities, and establish a national database of solar facility soil data that will hopefully shed light on how vegetation and land management at solar facilities can impact soil health over time.
REFERENCES
Agostini, A., M. Colauzzi, and S. Amaducci. 2021. Innovative agrivoltaic systems to produce sustainable energy: an economic and environmental assessment. Applied Energy.281: 116102.
Bai, Y. and M.F. Cotrufo. 2022. Grassland soil carbon sequestration: Current understanding, challenges, and solutions. Science. 377: 603–608.
Blaydes, H., S.G. Potts, J.D. Whyatt, and A. Armstrong. 2024. On-site floral resources and surrounding landscape characteristics impact pollinator biodiversity at solar parks. Ecological Solutions and Evidence. 5: e12307.
Choi, C.S., A.E. Cagle, J. Macknick, D.E. Bloom, J.S. Caplan, and S. Ravi. 2020. Effects of Revegetation on Soil Physical and Chemical Properties in Solar Photovoltaic Infrastructure. Frontiers in Environmental Science. 8: 140.
Choi, C.S., J. Macknick, Y. Li, D. Bloom, J. McCall, and S. Ravi. 2023. Environmental Co‐Benefits of Maintaining Native Vegetation with Solar Photovoltaic Infrastructure. Earth’s Future. 11: e2023EF003542.
Millenium Ecosystem Assessment (MEA). 2005. Ecosystems and Human Well-Being: Synthesis. Island Press, Washington, DC.
Moore, S., H. Graff, C. Ouellet, S. Leslie, D. Olweean, and A. Wycoff. 2021. Developing Utility-Scale Solar Power in Michigan at the Agriculture-Energy Nexus. Stakeholder Perspectives, Pollinator Habitat, and Trade-offs. Report for the Institute for Public Policy and Social Research, Michigan State University. Available at ippsr.msu.edu/mappr/developing-utility-scale-solar-power-michigan-agriculture-energy-nexus. Accessed March 29, 2024.
Sturchio, M.A. and A.K. Knapp. 2023. Ecovoltaic principles for a more sustainable, ecologically informed solar energy future. Nature Ecology & Evolution. 7: 1746-1749.
Tölgyesi, C., Z. Bátori, J. Pascarella, et al. 2023. Ecovoltaics: framework and future research directions to reconcile land-based solar power development with ecosystem conservation. Biological Conservation. 285: 110242.
Walston, L.J., Y. Li, H.M. Hartmann, J. Macknick, A. Hanson, C. Nootenboom, E. Lonsdorf, and J. Hellmann. 2021. Modeling the ecosystem services of native vegetation management practices at solar energy facilities in the Midwestern United States. Ecosystem Services. 47: 101227.
Walston, L.J., T. Barley, I. Bhandari, B. Campbell, J. McCall, H.M. Hartmann, and A.G. Dolezal. 2022. Opportunities for agrivoltaic systems to achieve synergistic food-energy-environmental needs and address sustainability goals. Frontiers in Sustainable Food Systems. 16: 932018.
Walston, L.J., H.M. Hartmann, L. Fox, J. Macknick, J. McCall, J. Janski, and L. Jenkins. 2024. If you build it, will they come? Insect community responses to habitat establishment at solar energy facilities in Minnesota, USA. Environmental Research Letters. 19: 014053.
Wratten, S.D., M. Gillespie, A. Decourtye, E. Mader, and N. Desneux. 2012. Pollinator habitat enhancement: benefits to other ecosystem services. Agriculture, Ecosystems & Environment. 159: 112-122.
https://www.agrisolarclearinghouse.org/wp-content/uploads/2024/10/image-13.png7201231A. J. Pucketthttps://www.agrisolarclearinghouse.org/wp-content/uploads/2022/02/AgriSolar_stacked_1-338x400.pngA. J. Puckett2024-10-01 10:26:092024-10-01 10:26:27Ecosystem Services of Habitat-Friendly Solar Energy
Solar grazing is a relatively new and growing industry that uses livestock—most commonly sheep—to graze solar sites as a form of vegetation management. Within these systems, graziers form a contract with site owners to be compensated a fee for grazing to promote a shared purpose of the land and reduce the usage of traditional, mechanical mowing. Solar grazing compared to traditional (gas-powered) vegetative maintenance offers benefits for the solar operator, grazier, and animals.
Graziers receive additional land access to expand their grazing operation in a financially stable way, while their animals have access to improved forage quality and shaded environments (Kampherbeek et al., 2023; Andrew et al., 2021; Maia et al., 2020). Solar operators gain community support from co-locating solar and agriculture while also improving soil health through proper grazing management (Pascaris et al., 2022; Makhijani, 2021). This section seeks to identify best management practices for solar grazing to capitalize on maximum benefits for those involved in the solar-grazing industry.
2. Land Access
One main component of solar grazing practices is to understand the importance of a contract that aligns with the specific elements of the operation and agreements between the involved parties. While solar grazing allows graziers to expand their access to land beyond their home farm, there are many factors to consider before getting involved in a (solar grazing) contract. The ability to have livestock on solar sites is dictated by the state, city, and site owner. For graziers interested in starting solar grazing, EIA’s Energy Mapping Tool is useful for finding constructed solar arrays across the United States.
A strong network of connections during this process is one of the greatest resources a potential solar grazier can have. The American Solar Grazing Association (ASGA) is a valuable organization for helping to establish connections with farmers and solar developers, providing several resources and recommendations to get started. The process of starting grazing at a solar site may not always be quick and easy, but with some patience, the benefits from having additional land access from solar greatly outweighs the challenges. As one of the first solar graziers in the U.S., Solar Sheep LLC’s Julie Bishop has experienced this firsthand.
2.1 Case Study: Julie Bishop, Solar Sheep LLC
Julie Bishop’s involvement in the solar grazing industry began with a snowball effect after receiving a herding dog. Once she acquired a herding dog for her grazing operation, she trained it in herding at her home, which progressed to owning ewes and lambs and operating a hobby sheep farm. Then, in 2013, Bishop discovered that there was a solar field just five miles from her New Jersey home. She soon realized that sheep could manage the vegetation just as well as the traditional gas-powered mowers that were used on the site. She then got to work to make her idea a reality.
Bishop began the lengthy process of getting her sheep on that solar site. The land had originally been used as agricultural land but had been forfeited for the sole use of solar. Bishop and the solar company had to go to the municipality to ask for agriculture to be reinstated at that site. Additionally, they had to appear in front of the zoning and planning departments, send a letter to the community, and hold an open comment period in order to receive a variance. Finally, after nearly a year, Bishop was approved to move forward and was able to bring her sheep on-site for grazing.
A sheep under solar panels. Photo: American Solar Grazing Association
Despite being one of the first solar graziers and not having connections to consult, Bishop was able to successfully manage her first site. News of this success spread, and additional companies reached out to Bishop to form new contracts. Since then, she has grazed in three states.
Bishop says that solar grazing changed her life. Once a teacher, she is now a successful farmer who is only able to have her sheep operating at a larger capacity than she initially anticipated because of solar grazing. Her home farm is six acres, but the solar sites she grazes provide her the space she needs to expand her operation. She is now at the point of maximum capacity unless she changes her management style.
Currently, Bishop puts dry ewes on the solar site in the spring, then adds and removes rams, and brings the ewes home at the end of the grazing season to lamb around November and December. The lambs are then weaned, and the dry ewes return to the solar site. To expand her operation, Bishop would instead start lambing on the solar site around April and May. While the lambing process requires a lot of initial work, it would lead to a less labor-intensive and lower input management for Bishop. Along with changing the way she grazes, Bishop is waiting for more solar sites that are in close proximity to her home farm.
In addition to the challenges with expanding, Bishop identified some aspects of solar sites that can prove difficult when compared to traditional sheep management, such as site layout, trucking in water, and exterior perimeter fences that lack proper predator-proofing. After years of experience, Bishop has the knowledge and practice to overcome these challenges. For example, she worked with the solar developer at a site to build a bracket to prevent sheep from rubbing up against an emergency switch. The bracket keeps the equipment safe from the sheep but still provides easy access for a person as needed.
Sheep moving through a solar site. Photo: AgriSolar Clearinghouse
The sites that Bishop grazes were not created with the intention of solar grazing, and this can lead to difficulties such as a poor line of sight when moving sheep. Bishop has been able to overcome this issue with the assistance of a well-trained herding dog. It is only fitting that the reason she became involved in the solar grazing industry is now one of her greatest assets.
In her solar grazing work, Bishop has seen a shift in community perception. During the initial stages of solar development, there was pushback from communities that did not want agricultural land being used for solar development. Once Bishop brought the idea of solar grazing to the community, there was still some hesitation toward the new concept, and no one knew what to expect. Her success has allowed the community to view dual-use solar in a different way, and there is now a positive perception of solar grazing in her area.
As one of the first solar graziers, Bishop is well equipped to provide advice to those looking to join the industry. She suggests teaming up with someone who has experience in solar grazing to learn the ins and outs of the practice. Additionally, patience is necessary. It is difficult to plan, and there are often periods of waiting for approvals and construction. Finally, she recommends carefully selecting sheep that will be a good fit for the management system.
Bishop is a true example of the beneficial opportunities that solar grazing can provide. The additional land access granted to her through her contracts allowed her to not only expand her operation, but also to become an innovator in the expanding industry.
3. Contracts
Once a grazier and solar developer have agreed to partner together to manage a site, a contract is needed. ASGA has partnered with the Food and Beverage Law Clinic at Pace University’s Elisabeth Haub School of Law to provide sample contracts for solar grazing. The contract serves as a template for a Master Services Agreement (MSA) involving all arrangements between the farmer and solar company. Additional Statements of Work (SOW) are included for specific terms within the contract.
ASGA’s sample contract provides an ideal starting point for conversations between solar graziers and solar operators. It is important to consider that every site will be different, and the contract can be adjusted as needed. To ensure proper maintenance of the site and the relationship between the grazier and solar operator, both parties must fully understand what services are included in their contract. As solar grazing gains popularity, many farmers enter into contracts that allow them to provide a hybrid vegetation-management approach where the graziers maintain all or most of the vegetation at the site, including clean-up mows following grazing or spot-spraying as needed. Contract lengths and fees will vary depending on the site, and it is important to determine the best approach for both parties. This concept is one that United Agrivoltaics is familiar with.
3.1 Case Study: Caleb Scott, United Agrivoltaics
Caleb Scott of United Agrivoltaics at a solar site. Photo: Caleb Scott
In 2012, Caleb Scott was working with solar developers to help seed and build sites. As he got more involved in the industry, his job expanded to help properly maintain these sites. Scott began mowing the solar sites but quickly realized it was a challenging task. Every site was different, with varying degrees of ground levelness, infrastructure spacing, and site vegetation-management requirements. Additionally, he had to be careful around the panels to avoid any damage from his equipment.
When not working on-site, Scott, a seventh-generation farmer, took care of his flock of sheep. He realized that sheep would do a much better job at vegetation management than mowers and would get around easier. However, despite his experience in managing sheep and solar vegetation, it was difficult to convince the industry that sheep could be a valuable form of vegetation management. Scott began to work with Cornell University to collaborate with solar developers and use the University’s property to perform a demonstration site for solar grazing. This work gave him proof of concept, and he began grazing on solar sites in 2013.
After Scott received his first solar grazing contract, he was able to grow and strengthen his practice. In addition to being a founding board member of the American Solar Grazing Association, he also created United Agrivoltaics, one of the first and oldest agrivoltaic sheep-grazing firms in the U.S. United Agrivoltaics functions as a co-operative to promote expansion of the solar grazing industry and now has 103 sites in nine states. The organization uses Scott’s unique background to provide vegetation management with solar grazing, as well as consulting to implement agrivoltaics on solar projects.
Scott and the other 80+ graziers involved with United Agrivoltaics pride themselves on creating a healthy, shared-use system. While their specialty is in solar grazing with sheep, they have also used chickens, turkeys, rabbits, and pigs to help maintain the site vegetation and increase the overall productivity of the site. Scott uses three different styles of grazing: mob, rotational, and low-impact sustained grazing. These management methods provide financial benefits in some cases and health benefits in others. Scott’s main priority when deciding which style to use depends on what is going to work best for the on-site forage content, as well as for his farm and animals.
United Agrivoltaics recognizes the variability between sites and offers different tiers of service to help overcome this. This is a major benefit for asset owners as it allows them to form a contract and relationship with one party for all their site-management needs. Scott’s full management package includes services such as exterior perimeter mows, spraying herbicide as needed to control noxious or invasive species, and a clean-up mow to manage the vegetation the sheep did not eat.
The flexibility of United Agrivoltaics’ services has helped the organization grow over time. They are currently grazing 15,000 sheep on more than 5,100 acres of solar sites, with a goal to double the number of sheep in the upcoming year. Scott himself is grazing 650 sheep on 200 acres, and this growth allowed solar grazing to become his full-time job. He and United Agrivoltaics have purchased and acquired other companies along the way to help them grow.
Sheep grazing the vegetation at a solar site. Photo: Caleb Scott
As United Agrivoltaics continues to expand, they ensure that their services remain competitive with the costs of mechanical mowing. The grazing costs will vary depending on location and which rating scale the site owner chooses for their site. In an area with farm readiness considerations being met, fees can range from $380/acre for the full management package to more than $1,500/acre. Despite the large range in pricing, Scott recognizes that generalizing pricing would have a negative impact on the solar grazing industry due to the number of variables that determine contract pricing, such as site management requirements and feasibility for the grazier.
In addition to difficulties associated with selecting the correct pricing for a site, insurance can be an added challenge when solar grazing, as extra costs typically do not outweigh the value of the contract. One of Scott’s biggest initial challenges in the solar grazing industry was learning to manage the site as dictated by the contract. In some cases, he has had to change his vision of what he thinks the site should look like in order to meet the site owner’s needs. Farming motives can differ from solar operation motives and requires calculating the correct stocking densities.
To help overcome these challenges, Scott’s advice is to reach out and talk to someone who has done it before to ask a lot of questions and educate yourself.
“This industry requires a lot of teamwork, especially since the solar grazing industry is so young and we have so few sheep in the country. We need to help and support one another.” — Caleb Scott.
A trio of sheep on a solar site. Photo: American Solar Grazing Association
Teaming up with individuals who have prior experience could allow for sharing things like insurance (costs), equipment, and other resources, which could mean saving additional money. It is also beneficial to discuss contracts with those who have experience. Scott recommends finding an organization, like ASGA, that helps farmers and joining them to learn and share ideas.
This teamwork represents Scott’s overall goal for the solar grazing industry and United Agrivoltaics, which is to have as many sheep in the organization as are currently in the U.S. right now–over 3 million. He wants to accomplish this by expanding his company and farming group nationwide. By doing so, he hopes to see the sheep industry increase tenfold in the next 20 years, and he wants to be a part of that change. If this were to be accomplished, it would undoubtedly afford tremendous benefits for the solar-grazing industry.
4. Operations and Maintenance Considerations
As mentioned in the Bishop and Scott case studies, when solar grazing was first introduced, the solar sites were created without any consideration for bringing animals on-site. With solar grazing and agrivoltaics gaining popularity, site developers can,and should, place emphasis on creating a livestock-friendly array. Areas of consideration include site preparation and vegetation establishment, costs, and creating a safe environment for the animals and graziers.
4.1 Site Preparation and Vegetation Establishment
When preparing a site for solar development with the intention of grazing, it is important to involve multiple stakeholders, including O&M producers, graziers, environmental scientists, and the community. Conversations with these stakeholders should focus on Macknick et al.’s 5 Cs of success: collaboration, compatibility, solar panel configuration, climate, and crop selection and cultivation (Macknick, 2022).
Establishing permanent pastures prior to site construction can improve soil health (Makhijani, 2021). Soil health can be monitored with soil testing over the project’s lifespan to ensure it is being properly managed. Diverse seed mixtures can provide optimal benefits for both site and animal health. For example, when grasses and legumes are sown together, the quality of forage and soil fertility is improved, with the higher-quality forage promoting animal health (Mamun et al., 2022; Andrew et al., 2024). Native and pollinator-friendly groundcover can also be considered, providing benefits for pollinators, the soil, and nearby agricultural land (Horowitz et al., 2020; Makhijani, 2021). No matter the approach to seeding a site, special care should be taken to avoid toxic or invasive species on-site and in perimeter areas.
4.2 Cost Considerations for Grazing-Intended Solar Sites
When establishing a solar site with the intention of including grazing animals, there are some additional considerations that can make a site easier to graze. These include providing water on-site, adjusting site layout to assist with rotational grazing, including permanent interior fencing, and in some cases—such as with grazing cows—raising the height of the panels. However, compared with the cost of photovoltaics over bare ground, solar grazing can reduce some site preparation costs related to clearing and grubbing, soil compaction, soil stripping, and stockpiling (Horowitz et al., 2020). Profits and costs are variable depending on the size and location of installations (Makhijani, 2021).
Graziers also need to consider O&M costs that may be different from a traditional grazing system, such as the cost of travel to and from the site, hauling water to sites without water access, and potentially purchasing additional equipment to perform vegetation maintenance. Many of these costs can help graziers negotiate their grazing fees and will vary from site to site. Additional budgets can be accessed from ASGA. Even with additional considerations, a survey by Kochendoerfer found grazing sheep on solar to be a cost-effective method to control on-site vegetation, benefiting the site owners and operators, as well as the graziers (2019).
4.3 Safety
Graziers and solar developers must ensure there will be no risk to the livestock, graziers, or solar operators. For example, all wiring, inverters, CAB systems, and other equipment should be inaccessible to the livestock. Proper fencing, signage, and security should also be in place. This involves ensuring fences used for livestock are predator-proof. Signs should be posted on gates informing workers when animals are present and that gates should remain closed, and providing contact information in case of emergencies. Additional safety concerns include avoiding contact with electricity, personal protective equipment, and specifying who may enter the site (Owens, 2023).
5. Animal Management Considerations
In addition to O&M considerations, there are different ways to use livestock to manage the site. Site management can involve different methods of grazing and different breeds of livestock. It is important to choose the proper breed of livestock that is most compatible with the site’s features, such as vegetation type and panel height.
5.1 Livestock Considerations
Sheep grazing is the most common form of solar grazing, though cattle, rabbits, poultry, honey bees, pigs, and other animal operations are possible (Horowitz et al., 2020; Macknick et al., 2022). One reason that sheep are most common is that they fit in sites with little to no modification of conventional structures. Additionally, they are not known to stand or jump on equipment, do not chew wiring, and do not cause damage if they rub against the equipment (MRSEC, 2020). There are projects that incorporate cattle, but this can require a higher panel height or different site design (Makhijani, 2021). Despite the added cost, the solar panels can provide shade benefits for cows and could be feasible for areas where sheep are less common (Sharpe et al., 2021). Lytle et al. (2021) found rabbits to be viable for agrivoltaics, providing a high-value agricultural product that increased site revenue by 2.5 to 24.0% with less environmental impact than that from cattle (Makhijani, 2021). Rabbits on solar sites would require additional considerations, such as ensuring the interior fencing extends below the ground and providing lightweight portable shelters to protect against aerial predators. Regardless of which livestock is selected for solar grazing, the grazier will need to consider management styles that benefit both the animals and the solar site.
5.2 Management Considerations
While grazing animals on a solar site, factors such as grazing management style, stocking density, and timing should be considered. A prescribed grazing plan (PGP) can create the framework for graziers to follow during the solar facility’s operation and includes gauging stocking rates, timing of grazing and rest periods, vegetation standards, soil conditions, and other similar details (Macknick et al., 2022). Forage testing can be used to ensure forage quality is being maintained. Rotational grazing has clear environmental benefits and is often used on solar sites. This method is known to improve soil health and forage yield compared to continuous grazing or mechanical mowing, further supporting stocking rates and economic returns to farmers (MRSEC, 2020). Other management styles, including mob grazing, low-impact grazing, or intensive grazing can be used, depending on forage availability and vegetation management goals. ASGA has released resources pertaining to the mechanics of solar grazing that can help determine the proper protocol for a site. Furthermore, combining solar grazing with pollinators demonstrates the potential for solar sites to include many ecosystem services, as shown by MNL.
5.3 Case Study: Jake Janski, MNL Pollinator Friendly Conservation Grazing
Pollinator plants with solar. Photo: Jake Janski
MNL is an organization with a mission to “Heal the Earth,” through ecological restoration and native species landscaping. As the organization progressed, they established projects on solar sites, including conservation grazing and prioritizing native seeds and plants that provide pollinator benefits. Jake Janski, who’s been with MNL for over 20 years, is one of the leading players for MNL’s conservation grazing projects.
Janski, Senior Ecologist and the Director of Strategic Planning with MNL, contributes to the organization’s pollinator-friendly solar projects. As he continued his work, he began to see more need for prairie management on solar sites than what mowers could successfully provide. In typical situations, prescribed burns are often used to create a disturbance event, further promoting the health of the prairie. However, prescribed burns could not be used at the solar sites, requiring an alternative method.
After meeting a sheep farmer in 2017 who lived near one of MNL’s pollinator-friendly solar sites, MNL decided to try sheep grazing to reinvigorate vegetation and remove dead thatch. With the timing falling at the beginning of the solar grazing industry’s development, and with Minnesota not having a large sheep industry, Janski focused on using sheep solely to help with the pollinator habitat. In other words, they used sheep as another tool for vegetation management and chose not to place the larger focus on sheep production. Janski started seeing surprisingly good results from this method and has built up from there, expanding MNL’s solar grazing projects.
MNL currently has about 60 Minnesota sites that incorporate solar grazing, with the average site being 20- to 00 acres and 2 to 10 kW. To date, they use 2,500 sheep, and they hope to expand their collaboration with other graziers to increase that number.
Sheep grazing amongst flowers at a solar site. Photo: AgriSolar Clearinghouse
The sheep graze the sites for two to four weeks to maintain the vegetation and account for stocking density. Since the sheep are used as a tool to promote pollinator habitat, there is some variability in animal management. There is an ideal time each year to graze the sites, but grazing at the same time each year would negatively interfere with the botanical species composition. To avoid this interference, MNL rotates the timing of grazing between years.
Occasionally, the site will be grazed at a prime time for pollinators; however, Janski identified benefits for pollinators resulting from carefully managed solar grazing. For example, grazing allows for more gradual blooming periods. Staggering or delaying blooming extends the flowering season and will provide different food sources at different times. Grazing is also less aggressive, with plants rebounding faster than they would following a mowing event. This method promotes wildlife such as songbirds, rodents, and reptiles.
Broadly speaking, Janski believes that grazing is far easier on all habitats. MNL has secured research funding to continue an on-going study investigating the grazing impacts on vegetation and plant communities at solar sites. The results from this study should further support the benefits of solar grazing.
Monarch caterpillar and solar. Photo: Jake Janski
Despite the benefits that Janski has observed over time, there are some challenges associated with promoting a healthy trifecta of solar energy production, pollinator habitat, and animal welfare and production. One of his greatest challenges is getting the price points that are needed to build a robust program. He is competing with some low-cost mowing companies, while also dealing with overwintering costs and expenses of hauling water to sites. Janski and the team at MNL had to learn new information at a quick pace about animal health, especially on a landscape with variable conditions. Over time, they’ve been able to create better systems and know what to plan for.
Bringing sheep on-site has made some aspects of site management easier. They are dealing with less equipment damage and healthier soil. The sheep have helped with weed control, and while they have not completely eliminated the need for spot spraying, they are creating healthier plants with more competition that should make weed infestations less likely over time.
Janski shared that there was a time when an electric short started a fire on a site; however, the sheep removed the majority of the fire fuel load, resulting in a low-intensity fire that did not get hot enough to cause any damage to the panels. This is in direct contrast to mowing, which leaves a lot of material on the ground, creating a thick dense layer of fuel for fires.
With such clear advantages, it is no wonder that solar grazing has helped ease the majority of public discomfort regarding solar. Janski recognizes that agrivoltaics (solar grazing and solar pollinator habitat) can be an important, multi-purpose system that benefits communities. He reports that every group that interacts with MNL wants to hear about solar grazing and that they enjoy seeing livestock on the land. This positive support is also helping to get policymakers on board. MNL is in discussions with the state of Minnesota about pollinator scorecards and updated policy-level incentives. Furthermore, the Minnesota Department of Agriculture is beginning to push solar grazing from an agricultural perspective, giving others the confidence to get behind it.
With an increase in community support, Janski recommends creating and maintaining good partnerships with solar companies. The solar industry is a much faster moving market than agriculture in general, so forming these relationships can provide valuable updates on developments within the solar industry.
This ties in with what Janski identified as MNL’s future goal: to get as far ahead of development as possible. They want to build sites that serve as a solar site and as a farm, with structures and paddocks pre-built. The sites will also promote pollinator habitat. To accomplish this, more market analysis is needed to show the importance of investing in agrivoltaic modifications at the start of site planning. Janski and MNL want to expand their reach to other states that are not yet as solar-heavy. This can be accomplished by serving as consultants to provide and share evidence and examples of sites that have seen beneficial progress during the development and operation of an agrivoltaic site to large audiences through marketing.
5.4 Goals and Benefits of Solar Grazing
The goals and management considerations will vary from site to site. Thus, there are certain goals that remain consistent across all sites (MRSEC, 2020), including preventing vegetation from shading solar panels, controlling invasive plant species, maintaining a diverse plant community, controlling erosion, and maximizing the opportunity for soil carbon sequestration by increasing topsoil and root mass. When managed correctly, grazing can satisfy all five soil health principles: “soil armor, minimizing soil disturbance, plant diversity, continual live plant/root, and livestock integration” (USDA NRCS, no date). In addition to improving soil health, water efficiency and biomass yield can be increased (Horowitz et al., 2020). To improve water quality, the vegetative quality of pastures should be promoted, soil health should be maintained, and grazing should be actively managed (MacDonald, 2021). Benefits of solar grazing are further supported by research from Handler and Pearce, who determined the global warming potential of agrivoltaics involving sheep is 3.9% better than conventional photovoltaics and grazing sheep separately (2022). These benefits further support the need for best management practices in solar grazing.
6. Conclusion
The goal of this section was to provide an overview of solar grazing and explain best management practices that provide optimal benefits for graziers, solar developers, and the environment. When done correctly, this growing industry has the potential to improve the solar and agricultural industries while promoting shared-use systems. The American Solar Grazing Association is working to publish a more in-depth review of solar grazing best management practices as part of a grant funded by the National Renewable Energy Laboratory’s InSPIRE Project, expected to be released by the end of 2024.
Andrew, Alyssa C., Chad W. Higgins, Mary A. Smallman, Maggie Graham, and Serkan Ates. 2021. Herbage Yield, Lamb Growth and Foraging Behavior in Agrivoltaic Production System. Frontiers in Sustainable Food Systems. April. doi.org/10.3389/fsufs.2021.659175
Andrew, Alyssa C., Chad W. Higgins, Mary A. Smallman, David E. Prado-Tarango, Adolfo Rosati, Shayan Ghajar, Maggie Graham, and Serkan Ates. 2024. Grass and Forage Science, Grassland Science Journal, Wiley Online Library. February 13. onlinelibrary.wiley.com/doi/abs/10.1111/gfs.12653
Handler, Robert and Joshua M. Pearce. 2022. Greener Sheep: Life Cycle Analysis of Integrated Sheep Agrivoltaic Systems. Cleaner Energy Systems. December. 100036. doi.org/10.1016/j.cles.2022.100036
Horowitz, Kelsey, Vignesh Ramasamy, Jordan Macknick, and Robert Margolis. 2020. Capital Costs for Dual-Use Photovoltaic Installations: 2020 Benchmark for Ground-Mounted PV Systems with Pollinator-Friendly Vegetation, Grazing, and Crops. NREL/TP-6A20-77811. National Renewable Energy Lab. Golden, CO. doi.org/10.2172/1756713
Kampherbeek, Emma W., Laura E. Webb, Beth J. Reynolds, Seeta A. Sistla, Marc R. Horney, Raimon Ripoll-Bosch, Jason P. Dubowsky, and Zachary D. McFarlane. 2023. A Preliminary Investigation of the Effect of Solar Panels and Rotation Frequency on the Grazing Behavior of Sheep (Ovis Aries) Grazing Dormant Pasture. Applied Animal Behaviour Science. January. 105799. doi.org/10.1016/j.applanim.2022.105799
Kochendoerfer, Nikola, Lexie Hain, and Michael L Thonney. No date. The Agricultural, Economic and Environmental Potential of Co-Locating Utility Scale Solar with Grazing Sheep.
Lytle, William, Theresa K. Meyer, Nagendra G. Tanikella, Laurie Burnham, Julie Engel, Chelsea Schelly, and Joshua M. Pearce. 2021. Conceptual Design and Rationale for a New Agrivoltaics Concept: Pasture-Raised Rabbits and Solar Farming. Journal of Cleaner Production. February. 124476. doi.org/10.1016/j.jclepro.2020.124476
MacDonald, Michael J, Margaret Chamas, Robert Goo, Lexie Hain, and Sharon Tregaskis. 2021. Animal Grazing Impacts on Water Quality at Solar Electric Generation Sites. American Solar Grazing Association.
Macknick, Jordan, Heidi Hartmann, Greg Barron-Gafford, Brenda Beatty, Robin Burton, Chong Seok-Choi, Matthew Davis, et al. 2022. The 5 Cs of Agrivoltaic Success Factors in the United States: Lessons from the InSPIRE Research Study. NREL/TP-6A20-83566. National Renewable Energy Lab, Golden, CO. doi.org/10.2172/1882930
Maia, Alex Sandro Campos, Eric de Andrade Culhari, Vinícius de França Carvalho Fonsêca, Hugo Fernando Maia Milan, and Kifle G Gebremedhin. 2020. Photovoltaic Panels as Shading Resources for Livestock. Journal of Cleaner Production. June. 120551. doi.org/10.1016/j.jclepro.2020.120551
Makhijani, Arjun. 2021,. Exploring Farming and Solar Synergies: An Analysis Using Maryland Data. Institute for Energy and Environmental Research. Takoma Park, MD. February. ieer.org/wp/wp-content/uploads/2021/02/Agrivoltaics-report-Arjun-Makhijani-final-2021-02-08.pdf
Mamun, Mohammad Abdullah Al, Paul Dargusch, David Wadley, Noor Azwa Zulkarnain, and Ammar Abdul Aziz. 2022. A Review of Research on Agrivoltaic Systems. Renewable and Sustainable Energy Reviews. June. 112351. doi.org/10.1016/j.rser.2022.112351
MNL. No date. Ecological Restoration and Minnesota Native Landscaping. Accessed March 15, 2024. mnlcorp.com/
Pascaris, Alexis S., Chelsea Schelly, Mark Rouleau, and Joshua M. Pearce. 2022. Do Agrivoltaics Improve Public Support for Solar? A Survey on Perceptions, Preferences, and Priorities. Green Technology, Resilience, and Sustainability. 2 (1): 8. doi.org/10.1007/s44173-022-00007-x.
Sharpe, K.T., B J. Heins, E.S. Buchanan, and M.H. Reese. 2021. Evaluation of Solar Photovoltaic Systems to Shade Cows in a Pasture-Based Dairy Herd. Journal of Dairy Science. 104 (3): 2794–2806. doi.org/10.3168/jds.2020-18821
https://www.agrisolarclearinghouse.org/wp-content/uploads/2024/09/Caleb-Scott-SGrazing-01-1.png367482A. J. Pucketthttps://www.agrisolarclearinghouse.org/wp-content/uploads/2022/02/AgriSolar_stacked_1-338x400.pngA. J. Puckett2024-09-30 10:14:132024-09-30 10:14:14Solar Grazing Best Management Practices
By Stacie Peterson, National Center for Appropriate Technology
Farmworkers are a particularly vulnerable population for heat-related illnesses because they perform manual labor outdoors, in direct sunlight, often in heavy, impermeable work clothing, during the hottest season (Association of Farmworker Opportunity Programs, 2024; El Khayat et al., 2022; EPA, 1983; Bethel and Harger, 2014). The trend of increasing temperatures globally will lead to an increase in heat-related deaths, heat stroke, and dehydration, as well as cardiovascular, respiratory, and cerebrovascular disease, particularly in sensitive populations (USGCRP, 2016). The United Federation of Farm Workers has called for workplace protection because farmworkers “are at the frontlines of climate change as extreme heat continues to expose them to more danger” (UFW, 2023). The workplace mortality rate for farmworkers from heat-related illness is 20 times higher than the U.S. civilian working population and this trend is increasing, as shown in Figure 1). A separate study by the National Institute of Health showed agricultural workers suffered heat-related mortality at a rate 35 times higher than all industries in the United States during the 10-year period of 2000 to 2010 (Gubernot et al., 2015).
Figure 1. Mortality Rate of Heat-Related Deaths Among U.S. Crop Workers (CDC, 2008).
In addition to mortality, many farmworkers experience heat-related illnesses such as heat exhaustion, heat stress, heat stroke, cramps, and rashes (Association of Farmworker Opportunity Programs, 2024). Several strategies can successfully alleviate heat stress and mortality. A consistent recommendation is providing farmworkers with access to shade (OSHA, 2023; EPA, 2023). However, farmworkers do not always have consistent access to shade (El Khayat, 2022). Solar arrays could provide this consistent shade, if designed to accommodate farmworkers, with a panel heigh of 6 to 8 feet. The image below shows the thermal image of a farmworker under a solar panel. The worker’s skin temperature is 80.9°F. The outdoor temperature was approximately 90°F.
Thermal image of farm worker under solar panel, showing external body temperature of 80.9°F with outdoor temperature of 90°F.
Heat stress also affects farm animal health. In a study of the thermal comfort and wellbeing experienced by dairy heifers provided solar panel shade, researchers showed that shade provided by the solar panels efficiently relieved heat load on the cattle, cooled off their body surface and skin temperatures by 10.8°F, and decreased the costs of thermoregulation (Faria et al., 2023). A study of heat stress, solar panels, and dairy cattle in Minnesota found a decrease in heat stress in dairy cattle under solar panel shade, corresponding to a decrease in body temperature (Sharpeet al., 2020).
A separate study on heat stress and sheep with access to solar panel shade found a decrease in wool-surface temperature in ewes ranging from 44.6°F to 46.4°F and a decrease in skin temperature of33.8°F to 34.7°F (Fonsêca et al., 2023).
Sheep grazing in the shade of solar panels.
Potential Solar Panel Shade Impacts
While touring agrisolar sites, the AgriSolar Clearinghouse team performed skin temperature readings under solar panels and in full sun. Table 1 shows the consistent decrease in skin temperature throughout the country, ranging from 7.8°F to 20.8°F, and the subsequent photos show infrared reading and skin temperature of a farm worker in Phoenix, Arizona.
Table 1. Skin Temperature Readings in Full Sun and Under Solar Panels
Agrisolar Location
Full Sun Skin Temperature (Fahrenheit)
Solar Shade Skin Temperature(Fahrenheit)
Skin Temperature Decrease(Fahrenheit)
Lake Pulaski, Minnesota
100.5
80.6
19.9
Monson, Massachusetts
101.3
93.5
7.8
Boulder, Colorado
90.7
75.4
15.3
Butte, Montana
101.2
81.8
19.4
Phoenix, Arizona
100.6
79.8
20.8
Champaign, Illinois
102.5
94.1
8.4
Skin temperature of 100.6°F in direct sunlight in Phoenix, Arizona.Skin temperature of 79.8°F in the shade of a solar panel in Phoenix, Arizona.
Based on skin temperature tests and animal testing at solar arrays, there is a potential for solar panels to provide shade to farmworkers and help alleviate heat stress. While other farmworker safety measures can and should be incorporated, such as water, rest, and acclimatization, a decrease of 10°F to 20°F could potentially alleviate heat-related illnesses and curb heat-related mortality. Additionally, timing agricultural work to coincide with the full shade of the solar panel and designing panel heights to accommodate farmworkers and animals, meaning a panel height of 6 to 8 feet, would ensure consistent access to the shade and its benefits.
References
Association of Farmworker Opportunity Programs. 2024. Heat Stress Prevention.
Bethel, J., and R. Harger. 2014. Heat-Related Illness among Oregon Farmworkers. (9), 9273-9285. doi:10.3390/ijerph110909273.
Centers for Disease Control (CDC). 2008. Heat-Related Deaths Among Crop Workers—United States, 1992-2006. Jama, 300(9), 1017. doi:10.1001/jama.300.9.1017.
El Khayat M, D.A. Halwani, Hneiny L, Alameddine I, Haidar MA, Habib RR. Impacts of Climate Change and Heat Stress on Farmworkers’ Health: A Scoping Review. 2022. Front Public Health. February 8. 10:782811. doi: 10.3389/fpubh.2022.782811. PMID: 35211437; PMCID: PMC8861180. Doi.org/10.1016/j.applanim.2023.105998
Faria, Ana Flávia, P.A., Alex S.C. Maia, Gustavo A.B. Moura, Vinícius F.C. Fonsêca, Sheila T. Nascimento, Hugo F.M. Milan, and Kifle G. Gebremedhin. 2023. Use of Solar Panels for Shade for Holstein Heifers Animals, No. 3: 329. doi.org/10.3390/ani13030329
Fonsêca, Vinicius de França Carvalho, Eric de Andrade Culhari, Gustavo André Bernado Moura, Sheila Tavares Nascimento, Hugo Maia Milan, Marcos Chiquitelli Neto, and Alex Sandro Campos Maia. 2023. Shade of solar panels relieves heat load of sheep. Applied Animal Behavior Science. Volume 265,105998, ISSN 0168-1591. Doi.org/10.1016/j.applanim.2023.105998
Gubernot, D.M., G.B. Anderson, and K.L. Hunting. Characterizing Occupational Heat-Related Mortality in the United States, 2000-2010: An Analysis Using the Census of Fatal Occupational Injuries database. 2015. Am J Ind Med. February. 58(2):203-11. doi: 10.1002/ajim.22381. PMID: 25603942; PMCID: PMC4657558.
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Sharpe, K.T., B.J. Heins, E.S. Buchanan, and M.H. Reese. Evaluation of solar photovoltaic systems to shade cows in a pasture-based dairy herd. J Dairy Sci. 2021 Mar;104(3):2794-2806. doi: 10.3168/jds.2020-18821. Epub 2020 Dec 25. PMID: 33358803.
United Farm Workers (UFW). 2023. Farm Workers Demand OSHA Issue Federal Heat Rule.
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https://www.agrisolarclearinghouse.org/wp-content/uploads/2024/08/Picture2.jpg519409Marisa Larsonhttps://www.agrisolarclearinghouse.org/wp-content/uploads/2022/02/AgriSolar_stacked_1-338x400.pngMarisa Larson2024-09-10 15:52:372024-09-10 15:52:38Solar Panel Shade and Potential Health Impacts
By Dan Salas, University of Illinois Chicago, Energy Resources Center – Sustainable Landscapes Program
The iconic monarch butterfly faces numerous threats in its migration across North America. Habitat loss, invasive species, pesticide use effects, disease, drought, and changing temperatures have collectively squeezed a vice of stressors on monarch butterfly populations. At the same time, the U.S. is undergoing a great energy transition towards renewable energy. Development of large utility-scale solar and other renewable energy projects is transforming landscapes in some parts of the country.
What will this energy transformation mean for pollinators like the monarch butterfly? That largely depends on the landscape change it brings. Fortunately, this changing landscape has given birth to a new form of land use: agrivoltaics. Agrivoltaics is the coupling of energy generation and agricultural production and can be represented by a mix of land uses that produce on-farm income, like grazing, crop production, or honeybee hive management. Agrivoltaics may also include ecovoltaics which often refers to establishing pollinator habitat. Such pollinator habitat can also benefit on-farm yields in surrounding croplands[1].
Can Solar Energize the Monarch Migration?
The Solar Futures Study[2] published in 2021 by the U.S. Department of Energy estimates that as much as 10.2 million acres may be required for solar development to achieve the 2050 renewable energy targets. Incorporating agrivoltaics into these changing lands can help diversify agricultural economies, reduce pesticide use, and increase pollinator habitat. But can these lands also help fuel the monarch migration?
The monarch butterfly population has undergone severe declines since the 1980s. This past winter (2023-2024) reported the second lowest populations for eastern monarch butterflies since they have been measured[3]. As noted, these declines are the result of a combination of factors, chief among them habitat loss and degradation. Loss of habitat reduces the butterflies’ resilience to other stressors, such as pesticide use, severe weather, and drought.
Pollinator Habitat Can be Risky Business
While greatly needed, creating pollinator habitat can be risky business for solar operators. But it’s not the potential for stinging insects that draws concern; statistically speaking, people have a better chance of dying from catastrophic storms than from a bee sting[6].
Rather, providing habitat to species at risk of extinction, while noble and beneficial, may unintentionally result in increased regulatory restrictions and operational limitations on a site operator. A species listed under the U.S. Endangered Species Act (or comparable tribal or state regulations) can add time, cost, and complexity to managing land and maintaining facilities over the life of a project.
Rewarding a Helping Hand
For this reason, the Rights-of-Way as Habitat Working Group, facilitated by the University of Illinois Chicago’s (UIC) Sustainable Landscapes Program, created a conservation agreement known as the Monarch CCAA (Candidate Conservation Agreement with Assurances). This agreement promotes upfront commitments to sustain or create habitat for the monarch butterfly. In exchange, companies receive regulatory assurances that no additional endangered species regulations will be required in recognition of their proactive conservation commitments.
This prospect has motivated solar developers and owners to consider enrolling in the program. Since its authorization in 2020, the program has resulted in over one million acres of monarch habitat commitments across the U.S. While being the largest voluntary conservation agreement in the U.S., it still requires more enrollment to achieve the levels of conservation needed for the butterfly. Previous studies have suggested that millions of acres of monarch habitat are required to achieve levels of conservation needed to avoid the threat of the migratory butterfly population’s extinction[7].
Biodiversity and wildlife habitat have been marginalized (literally) along field edges, fencerows, roadsides, and utility corridors. The Monarch CCAA offers energy and transportation land managers a chance to demonstrate commitments for monarch conservation, biodiversity net gain, and support for recovering other at-risk species.
Solar companies considering enrollment are encouraged to review resources available on the Monarch CCAA Toolkit[8], including enrollment guidance, webinars, and the application form. Contact UIC’s Sustainable Landscapes team with additional questions at dsalas4@uic.edu.
Learn More About the Monarch CCAA
The Rights-of-Way as Habitat Working Group at the University of Illinois-Chicago led a national collaborative effort to develop a voluntary conservation agreement to provide habitat for the monarch butterfly. The effort is unprecedented in terms of its cross-sector participation and geographic extent. The agreement spans the entire contiguous 48 states and is helping agencies and companies transform their vegetation management to benefit wildlife in need. Learn more at rightofway.erc.uic.edu/national-monarch-ccaa/.
About the University of Illinois Chicago Sustainable Landscapes Program
https://www.agrisolarclearinghouse.org/wp-content/uploads/2024/08/justin-docanto-q-i_sxORsqw-unsplash-scaled.jpg16002560A. J. Pucketthttps://www.agrisolarclearinghouse.org/wp-content/uploads/2022/02/AgriSolar_stacked_1-338x400.pngA. J. Puckett2024-08-22 13:09:592024-08-22 13:10:00Energizing the Monarch Butterfly Migration
Alexis Pascaris, National Renewable Energy Laboratory; Stacie Peterson, National Center for Appropriate Technology; Greg Plotkin, American Farmland Trust
This publication intends to inspire critical thinking about the importance of social aspects in agrisolar projects. We highlight considerations related to cultural landscapes, social acceptance, and participatory planning and offer lessons learned from case studies and a Stakeholder Engagement Plan to empower project planners and stakeholders. The intended audience for this chapter includes project planners, community developers, solar developers, researchers, landowners, and community members. While broad, the intent is to provide background, context, and considerations for these different audiences and an approach to meaningful engagement.
Agrisolar projects have the potential to benefit communities and ecosystems and contribute to our global sustainable development goals. Stakeholder engagement is required to advance socially acceptable, economically viable, and technically sound agrisolar development practices. A stakeholder can be an individual or organization that has interest in or is impacted by an agrisolar project. This can include but is not limited to landowners, farmers, ranchers, developers, community members, local officials, advocacy groups, and local organizations. In this chapter, the term stakeholder engagement is used to broadly address engagement of these actors, which is a critical component of developing equitable, inclusive, and sustainable agrisolar projects. The goal of stakeholder engagement is to build relationships, trust, and conditions that create mutually beneficial outcomes, such as diversified revenue streams for agricultural producers and host communities and the social license to operate in rural America for solar developers. When done well, stakeholder engagement can position agrisolar solutions for high social acceptance levels, build resilience in host communities, and maximize value for all involved parties.
“This might sound fuzzy, but real-world shovels in the ground (or not) can hinge on how [stakeholder engagement] is approached” (DOE, 2022).
Farm-to-table event at Jack’s Solar Garden. Photo: NCAT
The Importance of Cultural Landscapes
In this section, we discuss why it’s important to incorporate cultural landscape considerations into development decision-making. Cultural landscapes illustrate the relationship of people and communities with the land over time and are valuable to communities and cultures because they provide a source of identity and sense of place. When making changes to a landscape, it is important to understand whether this change could impact the sense of place, historical importance, or cultural identity associated with the landscape.
One way to approach this in decision-making is to use a cultural landscape framework. By understanding how the project could impact the cultural landscape and engaging with the community, developer, and landowner to address concerns, the project will have a greater chance of meaningful stakeholder engagement and community acceptance.
A cultural landscape framework can be used to better understand the interaction between people and place, particularly highlighting spaces where community members derive a part of their cultural identity (King, 2003), as well as reflecting how a community perceives, modifies, and interacts with their environment (Altschul, 2005). Cultural landscapes include historic designated landscapes; historic vernacular landscapes, including farm complexes; and ethnographic landscapes, which contain a variety of natural and cultural resources that associated people define as heritage resources (National Park Service, 2024). A cultural landscape includes the physical landscape and the history, heritage, sense of place, and cultural practices associated with that landscape over time (Smith, 2006).
The sense of place associated with a community can include the construction of community members’ position in both the physical and social world (Smith, 2006). In addition to providing a physical anchor in a geological space, it also allows for the negotiation of social value and cultural identity. Designations such as prime farmland serve as an authentication of significance to cultural landscapes (Little, 2003). These designations shape public perception of the place, including the people that live within it. During periods of conflict, cultural identity, sense of place, and cultural features can become more valuable to a community (Brown, 2003).
American farmlands and rural areas often contain cultural landscapes that are described in terms of the pastoral ideal (Marx, 2000). Industrial systems, such as a solar array, can pose a threat to the pastoral nature of a rural landscape and the cultural identity of the community. Agrisolar can serve as a potential solution by keeping the land in agricultural production or, if there is not a current agricultural practice, by incorporating agriculture into the project design. The solar array design can also incorporate low-impact design elements, follow the undulation of the landscape, and potentially incorporate innovative strategies, such as vertical panels, elevated or mobile racking, or semi-transparent panels.
Community engagement in Phoenix, Arizona. Photo: NCAT
The Importance of Inclusivity in Solar Energy Research and Development
In this section, we highlight considerations for inclusive research and development to demonstrate the importance of stakeholder engagement in this process. Lessons learned from agrisolar research and design experiences demonstrate how stakeholder engagement and participatory planning improves social acceptance, builds trust, and maximizes positive project outcomes.
Despite generally positive public perspectives on solar energy, abstract acceptance does not directly translate to concrete, local acceptance (Sütterlin and Siegrist, 2017). Continued solar development will require bridging this gap between general and local acceptance. Past experiences show how stakeholder engagement in research and design can address this gap and improve project outcomes (Schelly et al., 2019; Bessette et al., 2024). Researcher-led engagement can identify priority interests, values, and needs and enable generalization of key priorities to similar contexts to inform improved development practices across the United States. Developer-led engagement during the project process can translate stakeholder input into locally relevant benefits. Both types of engagement provide distinct value to current and future development efforts. Examples of engagement in research and design are provided in the “Community Engagement Examples” section below.
Stakeholder engagement, or lack thereof, directly impacts social perspectives of solar development, including agrisolar development. Opposition to solar stems from concerns with development processes and outcomes and is particularly correlated with the community’s participation in the project design, trust in the type of information provided by developers, and perceived project impacts (Bessette et al., 2024; Carlisle et al., 2016). Local opposition is among the leading causes of solar project cancellation in the United States and is becoming more frequent and expensive to address (Bessette et al., 2024). Local opposition, and its impacts on solar deployment efforts, may best be ameliorated through stakeholder engagement at all phases of a project and more social science aimed at understanding the varying causes of community opposition.
The positive influence of participatory planning and local ownership on social acceptance is consistent with other forms of renewable energy (Schreuer and Weismeier-Sammer, 2010), underscoring the importance of using stakeholder engagement to build trust and improve justice aspects of projects, which are often a concern (Banerjee et al., 2017). Increasing in-person interactions, discussing project tradeoffs openly, and creating local economic benefits and employment opportunities have been identified as the most effective community engagement strategies for solar development (Bessette et al., 2024).
By leading strong engagement efforts, solar developers establish credibility, include stakeholders in the strategic vision of a project, and ensure that development outcomes represent local interests and concerns, all of which maintain the social license to operate in a community. The concept of social license to operate was originally employed to describe social acceptability of mining operations and is now applied broadly to energy, agriculture, forestry, and other operations that impact natural resources (Moffatt et al., 2016). The demonstrated willingness of developers to be transparent and responsive creates proper conditions for sustainable solar development and increases the social license to operate. This is true for solar development broadly but is particularly important for agrisolar projects that involve a diverse set of stakeholders, land use practices, regulatory factors, and design considerations.
AgriSolar Clearinghouse stakeholders in Massachusetts. Photo: NCAT
Sustainable Agrisolar Requires Deep Collaboration
Stakeholder engagement is especially vital for agrisolar developments. The cross-sector nature of projects requires balancing diverse priorities to achieve common goals. Mutual learning, aimed at combining local agricultural knowledge with technical energy expertise, empowers agrarian communities to align projects with their needs and enables solar developers to deliver locally relevant solutions (Moore et al., 2022; Pascaris et al., 2023a, 2023b). This deep collaboration is the fabric of good agrisolar work, and clear understandings and agreements set the foundation for just outcomes, farm viability, and long-term project sustainability (Macknick et al., 2022). Because the potential loss of farmland is a main community concern with solar development (Bessette et al., 2024), thoughtful approaches are needed to protect agricultural heritage and create positive impacts on agricultural economies.
Agrisolar can improve development by retaining local agricultural interests and value. A public survey study found an increase in social acceptance of solar when it is co-located with agriculture (Pascaris et al., 2022). Similarly, in a survey of community members who live near large-scale solar developments in the United States, researchers at Lawrence Berkely National Laboratory found that projects incorporating agriculture or agrisolar were more favorable (Rand et al., 2024). While social acceptance is highly place-based, the potential for agrisolar to maintain agricultural community interests and reinvigorate public perspectives towards solar is appreciable. Solar developers, who are sensitive to community sentiment, also see value in agrisolar’s potential to foster favorable local conditions and improve their relationships with communities (Pascaris et al., 2021, 2023a). Higher levels of agrisolar acceptance of can be expected if local actors play a determining role in project development, especially if projects are community owned (Ketzer et al., 2019; Torma and Aschemann-Witzel, 2023).
Co-developing agrisolar projects with stakeholders not only stimulates greater social acceptance but also ensures farm operation compatibility and viable business models. Farmer engagement is critically important to the agrisolar development process; projects designed with long-term operational flexibility, and business models that feature fair distribution of benefits, is a requisite for farmer adoption of agrisolar (Pascaris et al., 2020; Torma and Aschemann-Witzel, 2023). Lessons learned from agrisolar efforts in the United States suggest that establishing clear roles and responsibilities, ownership agreements, and long-term plans for persistence of agricultural activities are key components of project success (Macknick et al., 2022).
When engaging with agricultural stakeholders, it’s essential to understand the mindset of farmers and landowners who are considering adopting agrisolar. Importantly, many farmers feel passionate about leaving a positive legacy and want to ensure land they’ve worked hard to steward continues to serve their community and support their families for years to come. The decisions to lease land to solar developers are often long, complicated, and stressful conversations for farm families to navigate. Outreach and engagement to farmers should be approached with empathy and understanding to frame conversations for success.
Community engagement at Connexus Energy. Photo: NCAT
Key Considerations for an Effective Stakeholder Engagement Plan
A stakeholder engagement plan is a framework that includes considerations for communication, participatory planning, feedback strategies, and target outcomes. The plan sets forth a process to identify, listen to, and collaborate with project stakeholders. A good plan features clear objectives, roles, resources, timelines, and actions and has dedicated the proper internal capacity to be managed over the lifetime of a project.
A range of responsible parties can lead a stakeholder engagement plan, including a solar development company, farmer, or landowner. Solar developers are typically responsible for the broad, multi-stakeholder engagement associated with the development process, whereas a farmer or landowner may lead an engagement effort to socialize a prospective project with their neighbors, solicit community feedback, and encourage local buy-in. The following outline of a stakeholder engagement plan suggests key considerations for responsible parties, namely solar developers, and is intended to promote agrisolar development that is more equitable, inclusive, and sustainable. Figure 1 provides a graphic representation of the process.
Figure 1: Example Stakeholder Engagement Plan. Graphic: NCAT
Define Goals and Outcomes
Determine the intended goals and outcomes of the stakeholder engagement effort. Effective engagement is objective-driven and is directly used to inform development decisions.
Consider conducting impact assessments. Environmental and social impact assessments can identify project-related challenges, risks, and opportunities. The insights derived through a project developer-led impact assessments can inform a risk mitigation plan.
Co-produce a Community Benefit Agreement. A key outcome of the stakeholder engagement effort could be an agreement between the responsible parties and host community that specifies benefits to be delivered in exchange for the social license to operate.
Get Acquainted and Determine the Scope of Stakeholders
Perform community discovery. This helps a solar company understand if there has been a history of development in the area. If so, who was involved and what were the outcomes? What is the general community sentiment towards solar development?
Conduct a stakeholder analysis. Project developers can consider how engagement strategies may vary across stakeholders deemed to have high interests and high influence versus others with lesser interest and influence. Available community engagement software tools can help with stakeholder mapping at this stage, such as A Quick Guide to Effective Stakeholder Mapping (Athuraliya, 2023).
Include traditionally excluded stakeholders and anyone who may be affected by the development. This could involve targeted efforts to build relationships and remove barriers to participation, such as inviting leaders of cultural groups to represent broader group interests in meetings or expanding accessibility through multilingual materials that broaden awareness.
Educate yourself about the issues facing farmers and landowners in the community. Understanding local issues, such as drought or loss of agriculture infrastructure, can help project developers better appreciate the farmer and landowner decision-making factors involved in agrisolar adoption.
Decide the Methods of Engagement
Develop an engagement strategy. Local meetings, presentations, and open houses are the most common and effective strategies led by solar companies (Bessette et al., 2024). Public hearings, town halls, one-on-one meetings, meditated discussions, and virtual information sessions are additional modes of engagement. Agrisolar-specific strategies can include farm-to-table events, tours, open forums, and educational workshops.
Consider sponsoring or attending events. Solar company presence where the agricultural community regularly gathers, such as state farm shows, farmers markets, trade shows, etc., can help build relationships. Farmers have little free time, so meeting them where they already are is an effective way to engage this important stakeholder group.
Use a combination of methods, tailored to the various stakeholder groups. Active stakeholders (i.e., high interest, high influence) should receive greater in-person engagement, whereas passive stakeholders require different communication strategies, such as media tools.
Prepare a timeline for implementation. Track the various engagement efforts and assign roles and responsibilities to the team.
Establish a Transparent Feedback Strategy
Determine what type of stakeholder feedback is needed and relevant. Participatory planning can be focused on informing acceptable project design (e.g., height, spacing, vegetation, and setbacks), or it can be focused on appropriate siting that avoids sites of cultural significance. Be clear about the bounds of input you intend to gather.
Create a plan for how stakeholder feedback will be used. Co-generation of outcomes and shared decision-making are hallmarks of effective stakeholder engagement (Prehoda et al., 2019; Kliskey et al., 2021), yet many developers prefer to solicit input rather than share decision-making power (Bessette et al., 2024; Nilson et al., 2024). Determine what is right for you, educate the community about what type of feedback is most valuable and can be acted upon, and be transparent about your plan.
Acknowledge that good feedback strategies are “two-way,” in that project developers not only solicit stakeholder input, but also actively respond to concerns and use them to inform decisions (DOE, 2022). Consider that some factors are outside of the project developer’s influence, such as hard costs and interconnection timelines, and cannot be directly shaped by community input.
Maintain Long-term Engagement
Explore post-construction engagement opportunities. Continue efforts to reach stakeholders who are new to the community or were not reached during the pre-construction engagement efforts by maintaining a presence in the community and facilitating gatherings.
Sustain stakeholder relationships. Solar companies can maintain strong community relations through ongoing listening sessions, community events, and continuous project improvements.
Use the project as a demonstrationand learning opportunity. Organize community events, develop research partnerships, leverage insights for education and information dissemination, and provide workforce development training opportunities.
Don’t miss storytelling opportunities. Both responsible and interested parties can follow up with farmers and landowners after projects are built to capture their stories. Compensating their participation in storytelling and elevating their voices is a great way to honor their lived experience, share lessons learned, and inspire the next generation of agrisolar projects.
The following examples demonstrate how stakeholder engagement has been used in agrisolar research and development in the United States.
American Farmland Trust’s Smart Solar in Connecticut Project
Recognizing the importance of stakeholder engagement in agrisolar research, the American Farmland Trust led a project effort aimed at capturing farmer, farm landowner, solar developer, land trust, environmental organization, and government official perspectives about solar on farmland in Connecticut. The interests and concerns identified in farmland solar were translated into state-level recommendations for appropriate strategies to minimize negative impacts and maximize benefits at the agriculture-energy nexus. The project’s multifaceted engagement methods, including the convening of an advisory committee, administration of a state-level farmer survey, facilitation of solar industry interviews and roundtable, and organization of agency briefings, is an exemplary approach to producing stakeholder-informed solutions. Through strategic coordination of stakeholders and co-developed research protocols, the American Farmland Trust, in partnership with AgriSolar Consulting, was able to deliver recommendations for agrisolar that reflect Connecticut stakeholder values to the Connecticut Department of Agriculture, Connecticut Department of Energy and Environmental Protection, and the Public Utilities Regulatory Authority. This project effort exhibits how robust stakeholder engagement in research can promote cross-sector collaboration and participatory processes that promote optimal agrisolar outcomes. This type of engagement is related to, but distinct from, project-specific engagement that should occur prior to development.
AgriSolar Clearinghouse
The AgriSolar Clearinghouse serves as a center for technical assistance, best practices, information sharing, and community engagement relevant to the co-location of agriculture and solar. The clearinghouse bases its stakeholder engagement work upon the tenets of connection, cooperation, and celebration. These tenets translate easily into any stakeholder engagement plan.
AgriSolar Clearinghouse Farm to Table Community Engagement Event. Photo: NCAT
The following information details the five elements of a stakeholder engagement plan implemented by the AgriSolar Clearinghouse.
Establish Goals and Objectives
The first step of the stakeholder engagement process included setting goals and objectives of the project, including resources to develop, technical assistance to offer, target audience, deliverables, project timelines, and project budgets. This work was performed with the U.S. Department of Energy’s Solar Energy Technology Office.
The second step included envisioning a diverse stakeholder group and the perspectives the stakeholder group would provide.
The third step included recruitment of a diverse stakeholder group that could represent solar grazing, crop co-location, solar beekeeping, pollinator advocates, researchers, farmland preservation groups, and rural community members.
Get Acquainted with Stakeholders and Define Their Scope
Monthly meetings with stakeholders during development of the clearinghouse website and its resources included presentations and discussion with stakeholders. This allowed ample time to learn stakeholder motivations, scope group objectives, and provide opportunity for stakeholders to connect and develop relationships.
Regular drafts of the website, statement of project objectives, and resources were provided to the stakeholders and discussed in monthly meetings. Feedback, such as additions to the information library, was incorporated before the next meeting.
Regular meetings, individual phone calls and video meetings, and an email group helped shape the scope of the website and the common definitions, goals, and community benefits of the clearinghouse.
Determine Methods of Engagement
The AgriSolar Clearinghouse was developed at the height of the COVID-19 pandemic and in-person meetings were not possible. Additionally, stakeholder group members reside throughout the country, and virtual meetings worked well from a practical standpoint. Engagement methods included virtual meetings, an email group, a forum within the website, and individual phone and video meetings.
As pandemic travel restrictions lifted, field trips and farm-to-table events provided excellent opportunities to connect, support agrisolar projects throughout the country, and collect stories from farmers, graziers, landowners, community members, and solar developers. Because food and food sharing are the basis of culture, they are an integral part of community engagement and important methods of engagement.
Virtual engagement pieces, such as short films, professional photographs, blogs, and case studies developed during the field trips, served to engage stakeholders who could not attend. Stakeholders helped identify the field trip sites and many traveled to attend the field trips, showing a high level of engagement.
Surveys are regularly offered to stakeholders and tour attendees and are available to the general public via the website. Feedback from surveys influenced website design and functionality.
To have a broad engagement reach, the AgriSolar Clearinghouse developed a wide array of technical assistance materials, such as a webinar and podcast series (both featured stakeholders), a short-film series, a case-study atlas, fact sheets, financial information, an abstracted library of peer-reviewed research, and a choose-your-own adventure guide for co-locating agriculture and solar.
Establish a Feedback Strategy
The feedback strategy for the AgriSolar Clearinghouse was developed around the stakeholder meetings. During the meetings, staff members kept a list of suggestions and feedback, and this feedback was incorporated before the next stakeholder meeting, where the action was discussed.
Stakeholders can see changes made to the website, resources, and events by reviewing the website and its resources and by attending the events.
Maintain a Long-Term Engagement Strategy
The long-term engagement strategy includes expanding the stakeholder group to include more members with more diverse perspectives, strengthening the existing stakeholder relationships, and asking for feedback and input regularly.
Field trips, farm-to-table events, webinars, and the creation of resources such as this Best Practices Guide provide excellent opportunities for substantial engagement and for learning vital stakeholder perspectives and knowledge.
Conclusion
Meaningful stakeholder engagement can increase community acceptance, build resilience in rural communities, and address cultural and community concerns early in the project planning process. By first working to understand the community, cultural landscape, and project goals, a stakeholder engagement plan can help stakeholders to shape the project and engagement methods in a way that is tailored to the community and the project goals. A transparent feedback strategy and long-term engagement plan will help create lasting local relationships and networks of support for an agrisolar project.
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By Stacie Peterson, PhD, NCAT; and Heidi Kolbeck-Urlacher, Center for Rural Affairs March 2024
Agrisolar practices, also called agrivoltaics, are the co-location of agriculture and solar within the landscape. They include solar co-located with crops, grazing, beekeeping, pollinator habitat, aquaculture, and farm or dairy processing. Agrisolar practices offer an opportunity to allow solar and agriculture to co-exist while meeting demands for clean energy and resilient rural infrastructure. One agrisolar approach is crop production under and adjacent to solar photovoltaics. Farms and research sites across the country demonstrate agrisolar as an opportunity to diversify farm revenue, decrease crop irrigation, increase crop yield, increase soil moisture, improve solar panel efficiency, and increase rural energy independence (Barron-Gafford, 2019; MacKnick, 2022; and Adeh, 2019).
Extreme heat and weather events from climate change, including the long-term drought in the American west, have led to water shortages, decreased crop yields, and increased heat stress for farm workers. Climate projections show this trend continuing, resulting in a marked decrease in crop yield in the future (Hsiagn, 2017). At the same time, an increasing population has elevated the need for nutritious local foods and food sovereignty.
https://www.agrisolarclearinghouse.org/wp-content/uploads/2024/02/OSU-solar.jpg433325Marisa Larsonhttps://www.agrisolarclearinghouse.org/wp-content/uploads/2022/02/AgriSolar_stacked_1-338x400.pngMarisa Larson2024-03-05 12:32:512024-06-17 13:16:12Fact Sheet: Making the Case for Crops + Solar
Compared to conventional solar energy developments, agrivoltaic systems may have different capital expenditures, cash flows, and risk impacts for a solar asset owner. Discussed herein are only broad, qualitative financial impacts, as there are too many agrivoltaic applications (e.g., over orchards, grasslands, croplands, livestock), solar designs (e.g., fixed-tilt, tracking, one or two panels in portrait), and local considerations (e.g., terrain, regulations, wildlife, agricultural markets) to share a concise financial impact assessment.
Financial impacts are labeled as either standard or potential considerations. Standard considerations are those that apply to agrivoltaic developments that can support diverse agricultural activities in addition to compatibility with small-scale machinery and agricultural laborers. Potential considerations are those that would apply only in specific circumstances.
This fact sheet focuses on new-build projects considering US federal and Colorado state-specific tax benefits, though most non-tax topics are more broadly applicable.
https://www.agrisolarclearinghouse.org/wp-content/uploads/2024/02/harvest-the-sun.jpg375500Marisa Larsonhttps://www.agrisolarclearinghouse.org/wp-content/uploads/2022/02/AgriSolar_stacked_1-338x400.pngMarisa Larson2024-02-08 11:04:522024-02-14 15:50:07Fact Sheet: Financial Considerations for Developing an Agrivoltaic System
Written for the AgriSolar Clearinghouse by Alexis Pascaris (Agrisolar Consulting) and Allison Jackson (Colorado Agrivoltaic Learning Center)
The Agrisolar Policy Guide was designed to facilitate policy learning and innovation in the United States. By collating existing initiatives and key provisions, this guide serves as a resource for regulators, land use planners, decision makers, and others who are interested in state-of-the-art agrisolar policy. The AgriSolar Clearinghouse is impartial towards policy; the intention of this guide is not to advocate for certain initiatives, but to provide a central platform for education and engagement. The goal of this guide is to support policy innovation for better co-location.
This guide serves as an introduction to the solar industry, relative to agrisolar development in the United States, community programs, and solar ownership or lease opportunities for homes, farms, and ranches. It covers ownership options for small-scale, single-user solar installations, community solar installations that distribute power throughout a community, and utility-scale installations that sell power to the utility, as well as common utility-scale land-lease components for landowners looking to allow a developer to construct and operate a solar installation on a portion of their land.
https://www.agrisolarclearinghouse.org/wp-content/uploads/2023/05/6-scaled.jpg17072560Carl Berntsenhttps://www.agrisolarclearinghouse.org/wp-content/uploads/2022/02/AgriSolar_stacked_1-338x400.pngCarl Berntsen2023-05-04 16:39:382023-08-17 14:20:45Agrisolar Ownership: A Guide for Farmers, Ranchers, Communities, and Landowners to Co-locate Agricultural Production and Solar Generation
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