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
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
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.
Caleb Scott of United Agrivoltaics at a solar site. Photo: Caleb Scott
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.
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.
A trio of sheep on a solar site. Photo: American Solar Grazing Association
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.
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.
https://www.agrisolarclearinghouse.org/wp-content/uploads/2024/09/Caleb-Scott-03.jpg387283A. J. Pucketthttps://www.agrisolarclearinghouse.org/wp-content/uploads/2022/02/AgriSolar_stacked_1-338x400.pngA. J. Puckett2024-09-17 09:19:552024-09-19 12:01:14Case Study: Caleb Scott, United Agrivoltaics
“Farmers are increasingly embracing solar as a buffer against volatile crop prices and rising expenses. Their incomes are heading for a 26% slide this year, the biggest drop since 2006, as cash receipts for corn, soy and sugar cane are expected to drop by double-digit percentages.
The shift is a big part of the renewables push in the US: The American Farmland Trust estimates that 83% of expected future solar development will take place on agricultural soil.” – bloomberg.com
Agrisolar Market Forecast to be Worth $10.64 Billion by 2033
“The Brainy Insights estimates that the USD 2.98 billion Agrivoltaics market will reach USD 10.64 billion by 2033. Increased government initiatives to boost R&D in agrivoltaics is one major factor that may create lucrative opportunities for agrivoltaics devices in the market. Governments across the globe have undergone tremendous initiatives to boost investments and increase subsidies in the market. To achieve net-zero carbon emissions the government across the globe is undergoing a renewable fuel-based economy.” – finance.yahoo.com
US Farms with Solar Have Tripled Since 2013
“Solar panels are gaining popularity across U.S. fields. In fact, there are now three times as many farms with solar installations compared to 2012.
In 2012, a little more than 36,000 U.S. farms had them installed. By 2017, that number had jumped to more than 90,000. In 2022, it shot up to nearly 120,000.
Successful Farming found some producers were being offered as much as $1,000 per acre to lease land for solar. While crops can net that much, the panels do not require any input costs like seed and fertilizer.” – rfdtv.com
https://www.agrisolarclearinghouse.org/wp-content/uploads/2022/10/agrisolar-roundup-photo-scaled.jpg25602378A. J. Pucketthttps://www.agrisolarclearinghouse.org/wp-content/uploads/2022/02/AgriSolar_stacked_1-338x400.pngA. J. Puckett2024-03-18 09:44:412024-03-18 09:46:45AgriSolar News Roundup: Stable Returns in Agrisolar, Agrisolar Market Forecast, Agrisolar Increase in US
This paper focuses on integrating agrivoltaics systems within super-intensive olive groves in the Mediterranean region. A dual model is used to calculate the suitable transparency of PV modules, representing the area not occupied by PV cells.
https://www.agrisolarclearinghouse.org/wp-content/uploads/2022/01/AgriSolar-Library-.png400600A. J. Pucketthttps://www.agrisolarclearinghouse.org/wp-content/uploads/2022/02/AgriSolar_stacked_1-338x400.pngA. J. Puckett2023-10-05 11:20:142024-03-20 08:33:01Potential of Agrivoltaics Systems Into Olive Groves in the Mediterranean Region
USDA Joins Great Plains Institute and Big River Farms in Minnesota Agrisolar Project
“Officials from the U.S. Department of Agriculture (USDA) joined Great Plains Institute (GPI) and Big River Farms announced GPI and Big River Farms’ ‘Solar Farmland Access for Emerging Farmers’ demonstration projects alongside project partners Connexus Energy and US Solar. As the country and Minnesota both take steps to convert our energy supply to be derived from carbon-free sources, this pilot project is setting out to solve for how solar energy development can be increased while also preserving agricultural land for the people who grow the state and nation’s food.
Funded by the Mortenson Family Foundation and with additional support from the National Renewable Energy Lab (NREL) and Argonne National Lab, these agrivoltaics projects aim to demonstrate safe and scalable operational practices for electric cooperatives and solar site owners to provide farmland access for emerging farmers inside the fence of solar facilities.” – Globenewswire.com
AgriSolar Clearinghouse’s Follow the Sun Tour Visits Oregon
The AgriSolar Clearinghouse’s Follow the Sun Tour visited the North Willamette Research and Extension Center in Aurora, Oregon, on September 18,2023. The research center hosts an agrivoltaic project, where the University of Oregon studies combining crops and solar energy on the same parcel of land. Event attendees participated in a tour of the agrivoltaic site, guided by lead researcher Dr. Chad Higgins. After the tour, everyone enjoyed a lunch and round-table discussion in the conference room of the facility.
Blue Wave in MA Secures $91 Million for Agrisolar Development
“Northeast U.S. solar developer and operator BlueWave received $91 million in financing, which the company says will allow it to achieve long-term ownership and management of its portfolio of projects.
The financing will go toward the construction of five projects featuring dual-use solar development attributes, called agrivoltaics, in Massachusetts. These projects are “strategically implemented to benefit all parties impacted by the projects,” including landowners, farmers and the surrounding community, according to BlueWave. The financing includes a $64 million debt raise with KeyBank, and $27 million tax equity raise with U.S. Bancorp Impact Finance.”– PV Magazine
Wisconsin Bill Introduces the Protecting Future Farmland Act
“U.S. Senators Tammy Baldwin (D-WI) and Chuck Grassley (R-IA) introduced the Protecting Future Farmland Act, new legislation to support farmers’ land stewardship efforts as many choose to deploy solar energy on their land. The legislation will ensure that federal investment in rural energy projects prioritizes both land stewardship and responsible deployment of renewable energy to protect America’s farmlands for future cultivation.” Senate.gov
https://www.agrisolarclearinghouse.org/wp-content/uploads/2022/05/agrisolar-roundup-photo-scaled.jpg25602378A. J. Pucketthttps://www.agrisolarclearinghouse.org/wp-content/uploads/2022/02/AgriSolar_stacked_1-338x400.pngA. J. Puckett2023-10-02 08:07:162024-03-13 10:55:18AgriSolar News Roundup: Minnesota Agrisolar Project, Follow the Sun Tour in Oregon, Agrisolar Funding in Massachusetts, Protecting Future Farmland Act in Wisconsin
This report updates readers on new research in dual-use solar and explores important considerations for the implementation of dual-use solar in the Pacific Northwest region. In the last few years, new findings suggest there are many environmental and economic benefits of creating multi functional systems that combine and prioritize multiple land uses. New research of dual-use solar facilities shows increased yields in some crops and decreased water needs; benefits to grazing animals such as decreased heat stress; improved ecosystem services such as better water quality, erosion control, carbon storage, and pollination services; and further opportunities for dual-use implementation.
https://www.agrisolarclearinghouse.org/wp-content/uploads/2022/01/AgriSolar-Library-.png400600A. J. Pucketthttps://www.agrisolarclearinghouse.org/wp-content/uploads/2022/02/AgriSolar_stacked_1-338x400.pngA. J. Puckett2023-09-29 12:54:302023-09-29 12:54:31Dual-Use Solar in the Pacific Northwest Summer 2023
In Ballground, Georgia, Jeffrey Whitmire and Chris Ayers, owners and operators of Chiktopia, are making use of an innovative solar technology that allows them to automate pastured poultry production while also practicing regenerative agriculture. Whitmire and Ayers, both students at the University of Georgia, produce and use fully automated solar-powered chicken coops on their operation, which they also sell to other farmers. In addition, Chicktopia provides regenerative grazing services to farmers.
These solar-powered chicken coops assist in building the topsoil (regenerative agriculture) using chickens. The self-moving, automated chicken coops makes spreading manure and flock rotations much easier for farmers and results in healthier soil with a higher level of organic matter. Chiktopia suggests that automated equipment such as these solar chicken coops are mandatory for regenerative agriculture in the future.
“At Chiktopia we believe sustainable farming practices are not only what are best for the planet but are also what create the happiest animals and the healthiest food. We help farmers minimize labor and maximize management.
Our automated chicken coops use renewable energy systems, which automate the majority of the labor in the pastured-poultry process. Whether it be for broilers or egg-layers our coop will help save you time and labor.” – Chiktopia
Chiktopia aims to help build a more resilient food system across the United States using pasture-raised poultry, says Whitmire.
The Regenerative Process
If a farmer wants a section of land to be converted into a regenerative crop farm, Chiktopia provides that service and process. The first step in the process is to put egg-laying hens on the land in the mobile, solar-powered coops. Once the hens are rotated through the whole pasture, dairy cows are then put on the land to spread more manure. This last step of the grazing process allows the soil to sustain more vegetation through increased microbe quality and carbon sequestration. This improvement in soil health is known as regenerative grazing.
Traditional Chicken Coops
A traditional chicken coop is made of steel and must be manually lifted or moved using a handle or trailer hitch on one end. This requires much more manual labor than having an automated coop. Moving these traditional coops causes the pasture to be damaged when chickens spend too much time in one spot. The mobility of the new solar-powered coop keeps the chickens from destroying the pasture and allows the organic matter in the soil to regenerate.
Solar-Powered Chicken Coops
The solar-powered chicken coops are equipped with an automated temperature-control system, automated chicken feeder, sun-tracking solar array system, automated pressurized watering system, automated egg collector, and even heat lamps for young chicks. These coops have a traditional hitch for farmers who might prefer moving the coop with ATVs or trucks, but they can also be easily moved with a handheld remote control.
When the coop moves, the birds don’t seem to mind at all. On the outside of the coup is an electrified perimeter fence that keeps the chickens in and predators out. When the hens are first put on a specific site, they spend a couple days in the coop getting comfortable with the new location, says Whitmire. They are then let out of the coop into the fencing area where they can roam.
The floor of the mobile coop is lined with plastic netting that allows the bird manure to fall to the pasture below. Feeders are aligned on the two sides of the coop above the netting where the birds tend to spend most of their time. When they aren’t feeding, there is a ladder in the center of the coop that allows the birds to get up near the ceiling and roost on installments designed for chicken roosting.
These automated, solar-powered chicken coops are available to order on Chiktopia’s website. Depending on the needs of the farmer and the design of the coop, costs can vary, ranging from $8,000 to $20,000. One coop created by Chiktopia houses up to 400 birds.
Predation Prevention and Shelter
These coops provide effective predation prevention. The sturdy cover provided by the coop protects hens from hawks and other predatory birds when they are inside. The coop’s design also reliably provides protection from harsh weather and other conditions that may make the birds uncomfortable or unsafe.
“We keep our birds protected through using strong materials on the coop and an electrified fence. Solar panels also reflect light at raptors.” – Chiktopia
Future Improvements
Chiktopia plans to make improvements to their coops, including a rainwater diverter that puts water directly into the watering tank that will be available to the chickens.
https://www.agrisolarclearinghouse.org/wp-content/uploads/2023/09/chicktopia-pic-4.jpg195259A. J. Pucketthttps://www.agrisolarclearinghouse.org/wp-content/uploads/2022/02/AgriSolar_stacked_1-338x400.pngA. J. Puckett2023-09-25 10:37:192023-09-25 10:37:20Chiktopia: Solar Grazing with Automated Chicken Coops
This paper highlights the higher annual solar irradiation incident of single-axis N-S trackers installed on sloping terrain, as compared to horizontal ones. Researchers showcase the results of a year-long experiment in which a N-S aligned single-axis tracker prototype was used in Gijón, Spain. The experimental results confirm the trends in the formulas and simulations. Finally, theoretical values for the energy gain for different slopes, at locations over the northern hemisphere between latitudes of 6◦ and 60◦ are provided. These gains can reach values up to 13.5%.
https://www.agrisolarclearinghouse.org/wp-content/uploads/2022/01/AgriSolar-Library-.png400600Anna Adairhttps://www.agrisolarclearinghouse.org/wp-content/uploads/2022/02/AgriSolar_stacked_1-338x400.pngAnna Adair2023-08-07 11:28:002023-08-07 11:28:01Experimental and numerical investigation of the influence of terrain slope on the performance of single-axis trackers
The Solar Shepherd provides grazing services in Brookfield, Massachusetts, with 75 sheep that graze a solar array site owned by SWEB Development, a European clean energy firm. This beneficial partnership was born when SWEB reached out to Solar Shepherd for grazing services after seeing their solar-grazing sites on social media. Learn more about the partnership in the AgriSolar Clearinghouse’s video How a Shepherd and Solar Developer are Joining Forces to Grow Sheep, Clean Energy.
Solar Shepherd’s founder and owner Dan Finnegan is a third- generation sheep farmer in eastern Massachusetts. His history working in a corporate environment led him to think more about what was important to him—the land, local farming, and clean energy. While he likes raising sheep, there wasn’t enough acreage for it to be profitable without agrisolar sites.
“It wouldn’t be enough to produce a living for a family,” he said. “This is more than a hobby-farming operation. With solar grazing, we dramatically expand our flock. We work hard to be competitive with landscapers on these sites. The grazing fees mitigate the costs and pay down the investment to take the show on the road (transporting sheep to solar sites). We’re used to farming out the back door, and now we have sites spread hundreds of miles apart. The grazing fees make that cost affordable.”
“I saw a solar array built on a lambing pasture, and a landscaper showed up with a tractor and started mowing up the solar arrays. He was going about 30 mph with a batwing sprayer and was mowing the rows and hosing down the panels around the arrays. I was thinking, they should just put the sheep down there and let them graze,” Dan recalled.
Solar Grazing Site Specifications and Management
The site is in a 15-acre array that produces 5 MW of DC and 3.375 MW of AC, enough to power approximately 1,100 homes. A landowner leases the land to SWEB, and SWEB hires Dan to graze the solar arrays with the sheep. The pricing is relatively the same as traditional mowing and gas-powered landscapers, but grazing sheep comes with many environmental benefits, such as enhanced landscape stabilization that directly benefits the solar companies. This stabilization includes deeper root systems on previously rocky terrain, improved turf health, and significant runoff reduction.
Solar Shepherd practices rotational grazing on their sites, which allows more carbon in the soil and retains more moisture. “We see that impact very rapidly. There are some sites we had that, in just one year, the customer came to us and said, ‘I can’t believe the impact the sheep had on the vegetation sustainability. It was rocky before, and now there are deeper root systems, stabilized soil.’ Erosion is a big concern at the base of the panels. A direct benefit to the solar companies is stabilizing that ground,” Dan added.
There’s also the “Fuzz and Buzz” – a solar seed blend used at the Brookfield site that benefits pollinators and sheep. It’s not as robust of a floral bloom, but the bees and sheep benefit greatly from this blend. A gas-powered mower removes all the vegetation on an array in a single day. The sheep take around a month to “mow” the same array. This allows valuable pollinator habitat to be left for the bees and birds. There’s good seed-to-solar contact, and the imprints from the sheep hooves allow the seeds to be captured in the soil. The sheep help the effectiveness of reseeding a site and some graziers will run the sheep back over the seeds to help stomp them down into the earth.
Solar grazing includes running three main operations: a sheep farm, a trucking company (as you move the animals), and a commercial landscaping business. “It’s more than just opening the gate, throwing the sheep in there, and driving away. There are always some sites that require things outside the lines,” said Dan.
Dan’s partner, border collie Reggie, has been vitally important in effectively managing the sheep on solar sites. In the trucking operation, sheep are loaded in and out of trucks over and over, and that requires collecting them from one site to another to be loaded into the trucks.
Reggie is immensely valuable in this process. She rounds up the sheep quickly, whereas it would take multiple human workers significantly more time. She is vital to effective time management (and cost, if you consider paying multiple workers to round up sheep all the time). Reggie moves the sheep around the array in accordance with rotational grazing practices.
Grant Incentives in Massachusetts
Massachusetts does have a grant program for dual use of solar (Massachusetts SMART Initiative), but it is “written in such a fashion that it can be difficult to be profitable,” said Dan. The grant does not apply to sites that already exist, and it requires panels to be built 10 feet off the ground. Solar Shepherd has not received this grant and has also not yet grazed an array that fits the 10-foot grant requirement.
Livestock production is diminishing in Massachusetts and what’s left is small-scale vegetable farming. Dan speculates that the state is writing laws for solar development incentives with this in mind instead of grazing sheep under solar panels.
Community Response
“The community loves what we’re up to,” said Dan. “We had about 500 comments (on the recent video featured on CBS) and all of them were loving what we are doing. There are a few political comments. So, grazing sheep on solar might bring some unification from a political perspective.”
He also added that, “At least half the time I show up, there is a family there outside the gate at the fence watching the sheep. People are wanting to bring kids out to the sites to see the sheep. I’d like to do a program where people can come see them. We would love to host a solar event. We’re going to bring some sheep to town off the hill in Brookfield so people can see them and interact with them. I have a dream of bringing a bus load of kids out here to see how bees, sheep, and everything all come together.”
Since the Brookfield location is an ancient hay site where indigenous peoples managed the land when colonists first arrived, not damaging the vegetation or compacting the soil during the solar array installation was very important. This priority to minimize damage to the land could have a positive impact on community support for a solar site, particularly on ancient farmland or similarly valued sites. Communities like to see that a (solar) development company cares about the land and the process of development.
Considerations for New Sheep Graziers
New sheep graziers or those thinking about getting into sheep grazing on solar sites should consider a couple of things throughout the process. Educating themselves on what’s happening on the solar array is very important. “They don’t have to be engineers,” says Dan, “but they should understand what’s happening and what the potential dangers are and keep themselves and animals away from those areas. Stay out of areas where you might think ‘I should have an electrician in there.’ These are areas that contain things like cable trays and equipment pads.”
Don’t move forward with grazing a solar site if you haven’t walked the location and examined it for suitable conditions for your sheep. If construction techniques did not leave a space where you would feel comfortable leaving the sheep, such as poor wire management or dangerous or sharp edges on array components, it may be a good decision to decline grazing in that location. Dan says the sites he turns down are for animal welfare reasons. There might not be enough nutrition on the site, but it is usually wiring management. A good perimeter fence can also make a site more ideal for sheep.
Operating a grazing operation on your own property requires having a plan for food and water delivery, as well as for avoiding predation. A plan should be in place for responding to issues that may arise on the site and with little notice. Solar Shepherd has a 24-7 hotline for such issues.
For fencing, Dan prefers to use electric netting, which provides effective protection from predators. Coyotes prefer to go under the fence rather than over it, and considering such nuances in predator-prevention strategies can help design a fencing system that is most effective for your area and your circumstances. Hiring people who think from the sheep’s perspective is important, says Dan. Fortunately, he has not had any issues with predation to his sheep.
The Future of Solar Shepherd and Solar Grazing
The future of Solar Shepherd is looking bright. It originally took the company approximately one year to get hooves on the ground at a solar site. Now it only takes about a week or two. “I feel great about the solar grazing future and Solar Shepherd. The sales pitches are getting shorter and shorter. The world is becoming aware of this subject. Five years ago, it was, ‘You’re doing what?!’ The last pitch I gave was an hour-long presentation. I got 15 minutes into the meeting, and people said, ‘It’s great; we are ready to sign.’”
https://www.agrisolarclearinghouse.org/wp-content/uploads/2023/07/FollowTheSun-0429-scaled.jpg17072560A. J. Pucketthttps://www.agrisolarclearinghouse.org/wp-content/uploads/2022/02/AgriSolar_stacked_1-338x400.pngA. J. Puckett2023-07-31 11:46:142023-08-01 13:04:37Solar Shepherd in Massachusetts: Solar Grazing
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