An aerial view of Jack’s Solar Garden

Jack’s Solar Garden is a  community solar garden in Boulder County, Colorado. With its 1.2-MW, single-axis tracking solar system, it is the largest commercial agrivoltaics research site in the United States. Covering over four acres of land on a 24-acre farm, Jack’s Solar Garden enables researchers from the National Renewable Energy Laboratory (NREL), Colorado State University (CSU), and the University of Arizona (UA) to study the microclimates created by its solar panels and how they impact vegetation growth. Additional partners include the Audubon Rockies, which planted over 3,000 perennials around the perimeter of the solar array, Sprout City Farms (SCF), the main cultivator of crops beneath the solar panels, and the Colorado Agrivoltaic Learning Center (CALC), which provides on-site educational opportunities for community groups to learn more about agrivoltaics. Jack’s Solar Garden also offers an annual stipend to an Artist on the Farm to engage the community on-site through their preferred art form. 

Electricity generated by Jack’s Solar Garden — enough to power about 300 average homes in Colorado annually — is sold to various subscribers via Xcel Energy’s Solar*Rewards Community program, where subscribers recieve a percentage of the net metered production as credits against their monthly electricity bills. Over 50 residents, five commercial entities (Terrapin Care Station, In The Flow: Boutique Cannabis, Western Disposal, Premiera Members Credit Union, and Meati), and two local governments (Boulder County and the City of Boulder) subscribe to Jack’s Solar Garden to support local, clean energy production, along with all the social and environmental benefits this development provides. Jack’s Solar Garden also donates 2% of its power production to low-income households through the Boulder County Housing Authority.  

Byron Kominek tilling under the panels at Jack’s Solar Garden

The solar array is designed to optimize electricity production while enabling researchers and agricultural workers to operate within the system. Torque tubes were elevated to 6-6.5 feet and 8 feet for two-thirds and one-third of the property, respectively, allowing researchers to study the difference these heights have on the microclimates and growing conditions of various crops within the solar array. During construction, land disturbance was minimized, leaving the long-standing brome and alfalfa forage relatively unharmed. Further, metal mesh was attached beneath the solar panels to help protect people within the solar array from electrical wires. 

Lettuce, Clary Sage, Grassland, and Raspberries all grown under the panels at Jack’s Solar Garden

Research at Jack’s Solar Garden includes: 

  • Crop Production and Irrigation Study to determine crop yields at different locations within the solar array with varying amounts of sunlight, shade, and allotted irrigation. 
  • Pollinator Habitat Research to measure the growth and performance of pollinator habitat seed mixes and evaluate different cost-effective vegetation-establishment techniques. 
  • Pasture Grass Research measuring the growth and performance of dryland pasture grass seed mixes with different cost-effective seeding methods. 
  • Grassland Ecology & Physiology Research seeking to understand the health and functions of grassland ecosystems within a solar array by studying light patterns, soil moisture retention, plant production and physiology, forage quality, and grassland resilience. 
  • Ecosystem Services Research evaluating multiple ecosystem services, such as carbon sequestration, erosion control, pollinator habitat, weed suppression, and microclimate moderation, provided by native vegetation and introduced pasture species within a solar array. 

These research projects were made possible through the dedication of the Kominek family, owners of Jack’s Solar Garden, to improve the economics of their hay farm while benefiting their local community. Local and State regulations supported the Kominek family’s ability to build Jack’s Solar Garden, including:  Colorado State legislation allowing for locally owned and interconnected community solar gardens as well as a Renewable Portfolio Standard that enables locally owned community solar gardens to generate 1.5x RECs per MWh; City of Boulder and Boulder County building codes requiring net zero for new homes  over 5,000 sq. Ft. and energy conservation codes that require either cannabis grow houses to pay taxes on energy consumed or to subscribe to local community solar gardens; and Boulder County’s Land Use Code update that provides solar array construction on prime farmland with a special land-use review process. 

Biosphere 2, located in Oracle, Arizona, houses one of the first agrivoltaic research sites in the United States. The site was built seven years ago with a 21.6-kW solar PV array shading a 9×18-meter garden. Greg Barron-Gafford, along with several graduate students, use this garden to study the changes in phenology of several varieties of vegetables and fruit, soil health, panel production, water consumption, and carbon scrubbing that are affected by the shading of the solar array. A control area of the same size with no shading was built within 10 feet of the solar garden for comparison. The fruits and vegetables grown here are tomatoes, caribe potatoes, butternut squash, red beans, bok choy, and basil.

Agrivoltaic solar garden at Biosphere 2. Photo: NCAT

Underneath the agrivoltaic solar PV array system. Photo: NCAT

Control garden at the Biosphere 2 agrivoltaic site. Photo: NCAT

Harvested food grown in the solar garden at Biosphere 2. Photo: Mariah Rogers, University of Arizona

Phenology, the study of the relationship between climate and plant life production and health, is a main focus at Biosphere 2. Graduate students are studying the timing of fruiting and/or flowering, along with plants’ dying cycle, at the solar garden and comparing these results to the full-sun control site. They are currently working with the National Phenology Network to share and analyze data. Soil health is also monitored by testing the amount of carbon in the soil. This is a slower process, as it takes time for carbon, microbes, and other organics to develop in dryland areas such as Arizona.

The students test the greenhouse gas consumption or carbon-scrubbing abilities of the plants as the conditions change. They track photosynthesis of the plants grown beneath the panels versus those grown in the control area to see when and for how long photosynthesis is affected by the hot climate and the shade. Plants’ ability to carbon scrub decreases in hot conditions, which in turn affects their health and growth patterns. This research is showing that plants can maximize their ability to carbon scrub under the solar panels due to the shading and reduced heat seen in dryland agriculture.

Rows of tomatoes and testing equipment at the solar garden. Photo: NCAT

The watering-treatment experiment tests the health and production of plants using two watering methods. Half of the plants are on a watering schedule based on what the plants in the control site need to flourish. The other half of test plants are watered half the time, therefore receiving half the water. Both watering schedules are used in the solar garden and control garden for comparison. These experiments are proving that shaded growing areas in dryland agriculture can use less irrigation water to grow crops if planted under a solar array.

The watering system at the Biosphere 2 solar garden. Photo: NCAT

Recently, these plants went through a blind taste test to see if there is any taste difference between the fruits and vegetables grown under solar versus under full sun. The main plants tested were tomatoes, beans, squash, and basil. Each plant group was harvested from both the control site and the solar site on the same day, washed the same, and presented the same. The study found that no significant taste difference was observed—good news for farmers worried about a change in flavor for their crops.

Sample preparation for the solar garden grown taste tests. Photo: Mariah Rogers, University of Arizona

The solar panel temperatures are being tested using thermocouples taped to the underside of the panels. Electricity flows easier in cooler conditions; thus, solar panels produce best when the underside of the panel stays under 75-80oF. The garden below creates a cooler environment for the panels than arrays with a gravel layout.

Thermocouples taped to the back of the solar PV panels. Photo: NCAT

Graduate students are also testing a remote sensing system at the solar site using satellite imaging and remote monitoring to learn whether remote sensors and monitoring are effective in site monitoring. This technology will hopefully help with site monitoring from a distance when travelling is not an option.

Greg Barron-Gafford and his team of graduate students are making leaps and bounds in agrivoltaic farming research. They hope to educate farmers across dryland agriculture and beyond on the double benefits of growing under solar panels while also producing electricity. To learn more about this program please watch the video below and visit Greg’s website. https://www.barrongafford.org/agrivoltaics.html

Pollinator-Friendly Solar in Plains, Georgia: A former U.S. president’s clean energy legacy

By Briana Kerber

Sunset with Gaillardia and Solar Array. Photo: Jill Stuckey

With clean energy developments continuing to ramp up across the United States, more attention is being paid toward how best to develop these projects at the pace and scale that the climate crisis requires while also ensuring that we are taking care of the sites and communities that host those projects.    That’s where a national project from the National Renewable Energy Laboratory (NREL), Great Plains Institute (GPI), Fresh Energy, and the University of Minnesota comes in. Funded by the U.S. Department of Energy’s (DOE) Solar Energy Technology Office, the Photovoltaic Stormwater Management Research and Testing (PV-SMaRT) project is using five existing ground-mounted photovoltaic (PV) solar sites across the United States to study stormwater infiltration and runoff at solar farms.

Together, the five sites represent a range of slopes, soil types, geographical locations, and PV configurations that will help solar developers and owners, utility companies, communities, and clean energy and climate advocates better understand how best to support solar projects and the host communities in which they are built, lowering the costs of clean energy development while ensuring protection of the host community’s surface and ground waters.

An early introduction to clean energy advocacy

Former President Jimmy Carter was an early advocate for clean energy development across the United States, from the West Wing of the White House to pockets of rural America, like his hometown of Plains, Georgia. Today, seven acres of a 25-acre parcel of former President Carter’s land, where peanuts and soybeans used to grow, is now home to a solar farm that can power more than half of Plains, a city of around 640 people. Situated in the middle of what is now a neighborhood, the project began when solar developer SolAmerica Energy approached the former President’s family about the possibility of installing panels on the land. That solar site now feeds into Georgia Power’s grid and is helping restore pollinator habitat, a well-known priority for former First Lady Rosalynn Carter, who helped create the Rosalynn Carter Butterfly Trail.

A flat site with sandy clay soil, Carter Farms hosts 3,852 solar panels to provide 1.3 megawatts of electricity to the Plains community via tracking, one-in-portrait arrays. As shown in Figure 1, the site is testing three separate seed mixes to monitor how the various ground cover intersects with stormwater management:

  1. Crabgrass, annual ryegrass, and panicum
  2. Low-diversity pollinator mix (seven species): Indian blanketflower, common sensitive-plant, butterfly milkweed, southern elephant’s-foot, finged bluestar, rayless sunflower, southern beardtongue
  3. High-diversity pollinator mix (18 species): Indian blanketflower, partridge pea, blackeyed Susan, yarrow, lanceleaf coreopsis, southern elephant’s-foot, mistflower, and others

Figure 1. A map of the seed mixes on six different plots at the Carter Farms solar site in Plains, Georgia. Graphict: Aaron Hanson

Since the site was first built to accommodate the solar industry standard of planting some sort of grass underneath the panels, which requires more frequent mowing, the PV-SMaRT team and local partners are still monitoring the six different plots at the Carter Farms site to determine the full impact of the pollinator-friendly seed mixes. Bodie Pennisi, a professor of horticulture with the University of Georgia, reports that, so far, the dominant grasses in the control areas have been crabgrass, annual ryegrass, and panicum. “2022 is the year when we expect the strongest bloom from the perennial species, and we are really excited to see what pollinators and other beneficial insects come to the flowers.” Although the site plots are still being monitored, that hasn’t stopped researchers and other project participants from drawing initial conclusions and getting excited about the many benefits the pollinator mixes will bring for biodiversity, the climate, and SolAmerica’s site management costs. Figure 3 shows a morning bloom of black-eyed susans from the high-diversity pollinator mix.

Figure 2. Blackeyed Susan flowers blooming at sunrise at the Carter Farms solar site. Photo: Jill Stuckey

Designing solar sites with extreme weather in mind

As discussed in Fresh Energy’s first PV-SMaRT case study on Connexus Energy’s Minnesota site, when engineers and researchers sit down to plan out or conduct analyses on clean energy developments like solar farms, they often utilize something called a design storm to test how well the site will hold up against an extreme weather event like a flood. A design storm is essentially a test flood event of a certain magnitude—the higher the magnitude, the more intense the test storm for modelling and analysis purposes. These tests help researchers and engineers monitor rainfall and soil moisture as well as determine how fast excess water soaks into the ground during extreme storms. Figure 3 shows the water monitoring equipment at the site.

Figure 3. Water monitoring equipment sits at the west end of the Carter Farms solar site. Photo: Jake Galzki

Jake Galzki, a University of Minnesota researcher who is part of the modeling team for the PV-SMaRT project, says, “The Carter Farms site has a deeper profile than other sites we’ve studied – it’s a meter and a half to the nearest restrictive layer. That means the rooting depth for ground cover is deeper than other sites. And the soil at this site is essentially a 1:1 sandy clay, meaning it is comprised of 50 percent clay and 50 percent sand.” He adds, “In terms of measuring the runoff at Carter Farms against the other four project sites, the runoff here is moderate despite being the wettest site we’ve studied. We noted good infiltration capacity when testing the 100-year design storm, but we also did see some runoff due to the high clay content of the soil, which is very typical during such extreme events.”

Aaron Hanson, energy program specialist at the University of Minnesota’s Institute on the Environment, says: “It’s great that we have such diversity among our research sites. The climate and soil conditions in southern Georgia are quite different from what we are used to in Minnesota. The ‘growing season’ is actually reversed. Rather than having snow cover in the winter, they have a dormant period during the heat of the summer. This diversity of research site conditions will ultimately help our model to be applicable for solar developments across the country.”

Craig Kvien, one member of the Georgia-based site management crew, is an agricultural specialist whose expertise with innovative solar and agricultural projects runs decades deep. Craig says that the process for tending to the plots has come with its challenges, namely weeds. “We’ve got a team of people who’ve been sampling and documenting the plant and insect species that are out there over time, including the ones we anticipated, and those we did not,” Craig says with a chuckle. He adds, “Part of the process for ensuring the pollinator mixes can thrive requires a good amount of effort to beat down the weeds that also want to grow.”

But Craig isn’t daunted by what he calls a “standard mix of hard-to-get-rid-of weeds, which includes briars.” When asked what it is about the project that excites him the most, he doesn’t hesitate to remark on the beauty of a multi-use property: “There are lots of options. It seems silly not to do something useful with the land underneath the solar panels, particularly if you can make a difference somehow, either by enhancing the pollinator species in the area—or making or saving an extra buck.”

Science reflected in the practice

Brian Ross, vice president of renewable energy at Great Plains Institute and project lead for PV-SMaRT, says, “This site in Georgia helps bring both scientific validity to the modeling and runoff coefficients, adding diversity of soil types, hydrology, and land use, but also to develop regulatory, permitting, and project best practices that flow from the science.” He adds, “Georgia regulators have been participating in these discussions and helping ensure that the science is ultimately reflected in the practice.”

John Buffington, vice president of SolAmerica Energy, says the pollinator piece was a key consideration for the company. “SolAmerica was originally motivated by the opportunity to contribute to the restoration of pollinator habitats,” John says. “We think supporting these initiatives is the right thing to do and gives us an opportunity to be a more engaged member of the communities in which our solar developments are located. Later, we were excited to hear about the stormwater and cost-management aspects of pollinator-friendly solar.”

According to John and the SolAmerica team, pollinator-friendly solar has the potential to change the whole solar industry. “We could have done a pollinator project and just been quiet about it,” he admits. “But that wasn’t the intent, because we were trying to inspire the industry, and the Carter site was a great vehicle for that. These pollinator-friendly and stormwater supporting practices help contribute to better management of a site by reducing the amount of our budget that goes to mowing and other maintenance. So, beyond the pollinator restoration aspect, there are clear business benefits to doing this with a solar site.”

Ongoing stakeholder feedback

Like the other PV-SMaRT sites, data and observations from the Carter Farms site now serve as a benchmark as the PV-SMaRT research team continues to gather insight about each of the five project sites across the country. Overall, ongoing findings at the Carter Farms site further validate the project’s recommended best practices for solar developments and stormwater management: We can help lower the soft cost of clean energy development and of ongoing maintenance, protect the host community’s surface and ground waters, create needed habitat, and sequester carbon in the soil, all while helping craft a truly sustainable clean energy future that will benefit everyone for generations to come—just as the Carters have long worked towards.

Throughout 2022, experts and stakeholders will be reconvening in this process to continue to examine and provide feedback on this foundational research. Read the first PV-SMaRT case study on Connexus Energy’s Minnesota site, get the latest updates from Great Plains Institute, and stay tuned for the third and final PV-SMaRT case study from Fresh Energy and partners.

A version of this article was originally published via Fresh Energy. Read it here.

In Warren County, Ohio, the Soil and Water Conservation District and the Park District collaborated to combine solar energy to power a park with pollinator habitat and an educational trail. The Solar Pollinator Habitat Discovery Trail was created to bring awareness to the public about clean energy and about the importance of pollinators to our food system.

Through a Power Purchase Agreement (PPA) with Rocknoll Energy Systems, a 275.6-kW solar array was installed and put into service in 2019. The system was designed to supply Armco Park with more than enough power to operate a pavilion, golf clubhouse, ball fields, and park shelters.

Photo: Warren County Soil and Water Conservation District

An Ohio Environmental Education Fund (OEEF) grant was awarded through the Ohio Environmental Protection Agency (OEPA) to develop the educational components of the project. This includes the Discovery Trail with seven interactive learning stations that highlight the science of pollinators and solar power. The station signage created by educators highlights the importance and natural behavior of pollinators and how individuals can create habitat for them. In addition, there are explanations of how solar panels work and the benefits of combining them with pollinator habitat.

The project also created an educational video series and a community involvement component. In the spring of 2021, community volunteers helped with the planting and watering of a native plant plot on the site. The site serves as a hub for the Conservation District and Park District to host in-person educational programs.

Photo: Warren County Soil and Water Conservation District

The trail’s creators hope it will help visitors take away knowledge about energy conservation and clean energy production, as well as how to help support pollinators through habitat development and protection.

Some institutions of higher learning are reducing fossil fuel use by investing in solar panel installations on campus. However, most of them don’t use grazing sheep to manage the grassland under their panels. In 2019, Susquehanna University (SU) in Selinsgrove, Pennsylvania put into service a 14-acre, 3-megawatt solar system, located on its Center for Environmental Education and Research property. The school leases a flock of sheep from Owens Farm, located near the University in Sunbury, Pennsylvania, to act as natural lawn mowers for the fenced solar array.

This solar project is a partnership between the university and WGL Energy Systems. WGL owns and operates the facility under a 25-year power purchase agreement (PPA), and Susquehanna purchases electricity back from WGL. Commercial PPAs such as this allow organizations like SU to buy power directly from the generating company and not an electric utility. This arrangement gives the generation company an incentive to invest in renewable generation installations, which is a key part of financing projects like this. A second company, SCG Power, provided design and construction services to the project.

Katahdin sheep grazing the grass aisles between solar panels. Photo: Susquehanna University

Caroline Owens of Owens Farm said that she dedicates 40 of her farm’s Katahdin sheep to fulfill the solar grazing contract with the university. Owens raises more than 100 sheep and works with the university to provide managed grazing under the panels throughout the pasture season each year. Owens is a member of the American Solar Grazing Association (ASGA), an organization promoting best practices for grazing livestock under solar panels. According to ASGA, solar grazing is one of the most common and effective ways to combine solar and agriculture, and sheep are among the best livestock choices for the task.

Sheep grazing in solar fields utilize the shade provided by the panels. Photo: Susquehanna University

Though Owens Farm is paid by Susquehanna University for the grazing services provided, the arrangement is mutually beneficial: Owens Farm gets extra income and access to more grazing land, and the university gets well managed vegetation, which is essential for optimal performance of the solar array. Both Owens Farm and the university are happy for the opportunity to show a working example of their shared commitment to reducing fossil fuel use. The partnership has another benefit, too, in the form of a learning opportunity each year for a Susquehanna University student who gets to be a shepherd for a season and help manage the flock.

Arnprior Solar site in fall and winter
All photos courtesy of EDF Renewables

EDF Renewables (EDFR) has dedicated its efforts for over 35 years to create a sustainable energy economy.  They have developed nearly 24 GW and continue to manage nearly 13 GW of wind and solar energy generating projects in North America.  Among these renewable energy sites is the Arnprior solar project located in Ottawa, Ontario, Canada. Arnprior is a 23.4MW array that sits on nearly 180 acres and provides enough power to meet the peak energy demands of around 7000 homes. When completed in 2009 the array doubled the solar PV energy generating capacity of the entire country of Canada. Six years after construction was completed, one of the landowners, Diane Egan, expressed an interest to EDFR on how the site would be returned to agricultural land after decommissioning.

Beehives at Arnprior

In 2015, the asset management team at EDFR started by curtailing the use of herbicides and pesticides, but they didn’t stop there on biodiverse and environmental projects at the site. By 2016, with all of the news coverage of decreasing bee populations, the team reached out to Marianne and Matt Gee of Gees Bees Honey Company to install hives at Arnprior. They started by installing two hives at the site that produced nearly 100 jars of honey per year. In 2022, there are now five hives that produce over 300 jars of honey annually.

Monarch larvae at Arnprior

In July of 2017, EDFR was awarded by the Government of Canada to provide a complete habitat for the monarch butterfly. The Arnprior site was the first of any solar project in Canada to be awarded by the Habitat Stewardship Program for Species at Risk (HSP SAR). EDFR formed a partnership with Victoria Wojcik and Kathleen Law of Pollinator Partnership, the worlds largest pollinator focused non-profit organization, to begin planting native wild flowers and milkweed. After a targeted seeding plan and professional training program, milkweed began to grow and thrive. Milkweed is the exclusive host plant that monarch larvae feed on. Within only one month of the award the larvae and iconic butterflies began to appear.

Chris Moore, Lyndsey Smith, and Bunny of Shady Creek Lamb Company

Furthermore in 2017, the Arnprior site launched a pilot program to use sheep grazing for vegetation management. Chris Moore and partner Lyndsey Smith of Shady Creek Lamb Company brought 50 ewes to manage the growth of the vegetation around the panels. EDFR found that not only did sheep grazing the vegetation under the solar panels align with vegetation management needs, but it also provided a mutually beneficial and effective solution for local sheep farmers interested in expanding their flock without having to buy or rent additional land.  Shady Creek Lamb Co. now had an opportunity to be paid for grazing.  Now in 2022, after lambing on-site, 500 sheep can be seen roaming around from spring to fall.  Shady Creek Lamb Co. has benefitted from dual-use by having access to additional land allowing them to expand their flock, grow their business and produce grass fed free range lamb and fiber for local markets.

Overall, the implementation of apiaries, monarch habitats and sheep grazing at the Arnprior site help to conserve farmland and promote healthy ecosystem biodiversity.  The site continues to maintain and expand the biodiversity projects exemplifying dual-use/agrivoltaics as a win-win solution for EDFR, the solar and agricultural communities and businesses being supplied by the honey, lamb, wool and electricity.

An ewe enjoys the shade of the solar array.
The flock is unaffected by the solar array

Cannon Valley Graziers is a vegetation-management company based in Southeastern Minnesota. Since 2018, Arlo Hark and Josephine Trople have been using their flock of sheep to manage vegetation in a variety of environments, working closely with customers to meet their management goals. Cannon Valley Graziers provides vegetation-management services for solar developers throughout southern Minnesota. The vegetation on community and utility solar sites is traditionally mowed multiple times per year, incurring high operations/maintenance costs. By applying adaptive-grazing strategies on these solar sites, Cannon Valley Graziers can reduce the annual maintenance costs for developers, while also having a positive impact on the soil health and water quality of southern Minnesota. 

Photo Courtesy of Cannon Valley Graziers

The principles of adaptive grazing are well-suited for vegetation management. By mob grazing—introducing a large number of sheep into a small area for a short amount of time—Hark is able to deploy his flock with surgical precision to meet the needs of each site. After the desired objectives are met, he moves the flock to the next site. Meanwhile, the vegetation is allowed to recover, strengthen its root systems, and grow more resilient. Hark says these root systems are key for soil regeneration and water quality. Deeper roots build organic matter and allow for the transfer of minerals deeper into the soil. Strong root systems also improve the soil’s ability to store and maintain water, which reduces soil erosion and chemical runoff into nearby waterways. 

Photo Courtesy of Cannon Valley Graziers

Growing a sheep-powered vegetation-management company is not without challenges. Large flocks require large trucks and trailers to move from site to site. In addition, most sites do not have water, so water must be supplied by the grazier. But to Hark, the effort is worth it. “It makes sense to stack benefits on these sites,” he explains. “We are providing a top-notch service to our customers, improving soil and water quality, and providing meat and fiber to our community. It just makes sense.”

By Briana Kerber, Fresh Energy

As we continue to deploy clean energy across the United States, more attention is being paid to how best to develop clean energy projects at the pace and scale that the climate crisis requires, while also ensuring that we are taking care of the sites and communities that host those projects. That’s where a national project from the National Renewable Energy Laboratory (NREL), Great Plains Institute (GPI), Fresh Energy, and the University of Minnesota comes in. Funded by the U.S. Department of Energy’s (DOE) Solar Energy Technology office, the Photovoltaic Stormwater Management Research and Testing (PV-SMaRT) project is using five existing ground-mounted photovoltaic (PV) solar sites across the United States to study stormwater infiltration and runoff at solar farms.

Jake Galzki, researcher at the University of Minnesota, measures water infiltration and runoff at Connexus Energy’s Ramsey Renewable Station site. Photo: Aaron Hanson

Together, the five sites represent a range of slopes, soil types, geographical locations, and PV configurations that will help solar developers and owners, utility companies, communities, and clean energy and climate advocates better understand how best to support solar projects and the host communities in which they are built, in particular lowering the costs of clean energy development while ensuring protection of the host community’s surface and ground waters.

On the banks of the Mississippi

With black-eyed Susan flowers dotting its expanse, the Minnesota site stands out among the five sites in the project. Situated on 18 acres of county-owned land near the Mississippi River in Ramsey, Minnesota, 30 miles northwest of the Minneapolis-St. Paul metro area, Connexus Energy’s Ramsey Renewable Station is flanked by an RV service center to its east, a highway to the north, and a specialty vegetable farm that grows pumpkins and peppers on the project’s west and south sides. Thanks to a partnership with the team at Bare Honey, a Minnesota-based honey producer, the site hosts beehives, too. The 3.4 megawatts of solar panels face south, in a two-in-portrait configuration on a fixed-mount racking system. Throughout the array, the panels are 24-36″ above the ground at the lowest edge.

Blanketed with sandy soil, the Connexus site was seeded with a pollinator-friendly vegetation mix throughout the array and open areas. And the pollinator-friendly aspect was the lynch pin in garnering community support. Pollinator experts and ecologists testified this wouldn’t be just any solar development—it would be a seasonally blooming, low-growing meadow, giving work opportunities to local seeders and apiaries as well as providing ecological benefits to the nearby crops surrounding watershed. Between the sandy soil and the ground cover, when it rains—or even pours—any excess water is channeled into the ground. And that has significant meaning for researchers, solar developers, utilities, and clean energy advocates alike.  

The Minnesota PV-SMaRT site, developed by Engie Distributed Solar for Minnesota’s Connexus Energy. Photo:Aaron Hanson


Designing solar sites for extreme weather

Part of the process of planning out or conducting analyses on clean energy developments like solar farms is to test how well the site will hold up against an extreme weather event, like a flood. Engineers and researchers utilized three different design storms, essentially model storms of various magnitudes, to test Ramsey Renewable Station’s response and evaluate rainfall and soil moisture as well as determine how fast excess water would soak into the ground.

Through these models, the PV-SMaRT research team discovered that, against three design storms—two-year frequency storm, 10-year frequency storm, and 100-year frequency storm, the most intense of the three—all stormwater was channeled into the soil by the deep-rooted vegetation. Using both an InVEST modeling framework and a 2D Hydrus water model, University of Minnesota (UMN) researchers involved in the PV-SMaRT project, including Aaron Hanson and Jake Galzki, led by UMN professor Dr. David Mulla, have been able to keep tabs on the site, monitoring data from moisture sensors and comparing numbers from the site to those of other PV-SMaRT locations.

In fact, the team found that if they wanted to observe a runoff response, they had to actually reverse engineer the site to provoke one. For example, if the team conducted a model of the site in which vegetation suffered due to heavily compacted soil, then they could observe a runoff response. But, in virtually every other scenario, the combination of the diverse, deep-rooted pollinator-friendly vegetation and sandy soil ensures that all excess water soaks directly into the ground. In the research team’s eyes, that made the Connexus Energy Ramsey site a prototype for the rest of the PV-SMaRT project.

Benefits for the site and the study

And Brian believes that those involved in stormwater permitting at solar sites can learn something from the Ramsey example. “As a result of this study, stormwater permitting at sites such as this can be predictable and transparent to both the city or county and the developer,” he says, “reducing soft costs for solar developers while ensuring good water quality outcomes for regulators and habitat co-benefits for local communities.”

Vice President of Renewable Energy at GPI, Brian Ross notes that the site is important because it serves as a sort of bookend for the project: “It is a site that requires only ground cover green infrastructure in almost any circumstances. Comparing this site to our other project sites is incredibly useful. The characteristics at play at Connexus Energy’s Ramsey solar site point toward the potential capacity of a solar farm to mitigate not only the site but also contribute to broader watershed management.”

At Connexus Energy, Rob Davis, communications lead, points out that there was an overwhelmingly positive community response to the pollinator-friendly aspects of the project. “That’s why Connexus requires pollinator-friendly ground cover for all our solar sites, and it was especially important for this project due to the location near the Mississippi River and a specialty crop grower. The site’s soil and ground cover combine to easily handle heavy rainfall events,” he says.

Jake Galzki, researcher at the University of Minnesota, inspects soil and water monitoring equipment at Connexus Energy’s Ramsey Renewable Station site. Photo:Aaron Hanson

Rob notes that when the project was built, it did not have the advantage of accurate hydrological models for PV solar projects, which resulted in a requirement for grading that included carving a two-foot bump diagonally through the project. Thanks to insights from the PV-SMaRT study, Rob is confident that policy changes can be made to avoid grading in the future, as it unnecessarily disturbs the soil and creates an uneven surface for vehicles managing a site. In its place, Rob points to the high-performance vegetation, as it requires less grading and fewer stormwater containment basins and is therefore a much better use of limited maintenance funds.

Insights yet to come

Data and observations from the Connexus Ramsey site serve as a benchmark as the PV-SMaRT research team continues to gather insight about the four other project sites across the country. Overall, the findings from the Ramsey site further validate the project’s recommended best practices in exemplifying how we can lower the soft costs of clean energy development and of ongoing maintenance while protecting the host community’s surface and ground waters, create needed habitat, sequester carbon in the soil, and help craft a truly sustainable clean energy future that will benefit everyone for generations to come. Read more about ongoing validation of this foundational research via Great Plains Institute.

A version of this article was originally published via Fresh Energy. Read it here.

Farmer-members of Organic Valley, a farmer-owned cooperative representing nearly 1,800 family farms, can now access renewable energy options for their operations. In Vermont, solar development company SunCommon has created a program to help Organic Valley farmers access and implement solar energy. SunCommon provides the financing and ownership options for solar array installation so that farmers have no upfront costs while offsetting their energy usage and receiving credits on their utility bills.

Photo Courtesy of SunCommon and Choiniere Family Farm

SunCommon offers a variety of system sizes, ranging from smaller systems to meet the needs of a single farm to community-scale systems that can power a farm plus 40 to 50 homes. The company has so far assisted 75 farmers in Vermont and New York implement solar energy, including the Choiniere Family Farm in Highgate, Vermont, which had farm infrastructure that they were planning to retire from production because of its depreciation. When the opportunity to install solar became available, the Choiniere family happily signed on, since the Organic Valley investment made the project low-risk. It turned out to be a good decision: the Choinieres were able to revive the barn by installing solar panels on the roof, which adds overall value, and turn the barn into a new milking parlor. SunCommon helped this family farm install panels that can produce 115,500 kWh each year, saving them $20,000 annually.

Photo Courtesy of SunCommon and Choiniere Family Farm

Organic Valley is the largest farmer-owned organic cooperative in the United States, with over 100 farmer-members in the state of Vermont. This program is currently accepting new Organic Valley farmers to participate. If you are in Vermont or New York and want to take advantage of reduced costs through solar energy generation with no upfront costs, follow this link to learn more.

The North American Center for Saffron Research and Development is conducting a multi-year study of saffron crops grown under and adjacent to ground-mounted solar arrays. The study, which began in 2015, includes two years of field data from the Peak Electric solar field in Burlington, Vermont.

Researchers established the saffron corms in three locations within the solar field: in the aisles; directly under the solar panels; and around the perimeter of the arrays. These three locations include both raised beds and in-ground planting methods.

Saffron is a perennial crop suitable for sunny locations in arid and semi-arid regions. It is relatively resistant to cold. Yields typically increase for three years after planting, often increasing exponentially between the second and third years. Saffron is a high-value crop, with values ranging from $19-$55/gram retail. It is also a hand-harvested crop, making it well-suited for agrivoltaics.

In the first year of the field trial, the saffron yield was low, as expected for newly planted saffron corms, with a higher yield in the raised bed plots. The second year of the trial produced higher-than-average yields, with some plots producing yields three times higher –than averages. 

Highest yields occurred in the lots located in the aisle and around the perimeter of the solar panels, with yields of 17 pounds of saffron/acre, which would be equal to $192,775/acre at an average price of $25/gram. 

The plots directly under the solar panels did not show this increase in production. These plots showed a 30% decrease in yield, indicating that the area under the panels is not an ideal micro climate for saffron production. Figure 1 shows the average yield of the harvested saffron per acre during the field trial.

Figure 1. Average yield of harvested saffron per acre during 2019 and 2020. (Ghalehgolabbehbahani et al., 2022)

Research will continue at this facility and the AgriSolar Clearinghouse will plan a field trip for the public in the fall of 2022. The annual report for this study is available in the Information Library here.

Reference

Ghalehgolabbehbahani et al., 2022. Saffron and Solar Farms: A Win/Win for Environment and Agriculture. North American Center for Saffron Research and Development, Burlington VT.