Written for the AgriSolar Clearinghouse by Center for Rural Affairs
Tag Archive for: Pollinators
Lake Pulaski is an agrivoltaic solar power plant site developed by Enel Green Power that spans over 68.2 acres in Buffalo, Minnesota. This site is one of 16 developed for the Aurora Distributed Solar LLC project in 2017, supporting pollinators, grazing, and an apiary. The layout consists of 34,668 panels at 315 watts each, spanning over 500 individual arrays. The total plant system size is 10.92MW (dc). Each panel has a SolTech single, horizontal axis tracker to follow the sun path and optimize production. This tracker was chosen over the more standard axis-pole trackers due to their ability to allow curves in the array installation to accommodate the rolling landscape. The developers strived to install the system with minimal land disturbance to maintain the landscape and reduce excavation, thus allowing the panels to move with the rolling hills. Panel height was design to be approximately 2.5 fee from the ground at the maximum tilt angle of 45o to allow grazing sheep to pass under without harm to sheep or panels. This sets the total height of each array at a maximum of 10 feet.
The landscape is grazed once a year near the end of September for one month to reduce the need for mowing, save on labor and gas, and maintain a healthy soil chemistry. Graduate students at Temple University in Pennsylvania are conducting studies on the benefits of grazing, such as soil composition, a reduced mowing, and a reduction in spraying for weeds. Eight of the 16 Aurora project sites are grazed for research purposes. Occasional mowing is required if the area has a high-growth year. Minnesota Native Landscapes (MNL) developed the original native seed profile to help promote pollinator activity under the panels. The final seeding was completed by Westwood Professional Services. MNL also maintains the pollinator and native landscape. Bare-grounded spraying is used to kill off unwanted invasive species, such as thistle. These areas are then fenced off to prevent wildlife and sheep in the area. Soil samples are taken from sprayed and mowed areas for research. Lake Pulaski also promotes the bee population by allowing bee farmers to move their hives next to the site to help pollinate the area and grow healthier bees.
Lake Pulaski is not without maintenance needs. The enormity and complexity of the site requires technicians, plant experts, landscapers, and sheep farmers to ensure that the site function as designed. Enel Green Power does most of the technical maintenance, while MNL sprays and maintains the plants. The SolTech trackers require slightly more maintenance than pole trackers, and they can go offline due to storms, sheep knocking the sensors, and other natural causes. Background research is being conducted by ENEL to determine whether the tracking system is worth the extra maintenance. At the end of the site’s service life, which is typically 25 years, the developers hope to decommission the system and return the land to agriculture with richer soil than the gravel alternative and unharmed adjacent landscapes. The research from this site will help quantify the benefits that agrivoltaics can bring to both solar development and agriculture industries.
By Briana Kerber, Fresh Energy
Developer: Pine Gate Renewables
Location: Medford, Oregon
Size: 13 MW, 41 acres (scorecard)
Soil type: Clay
Annual precipitation: 49 inches
Ground cover: A diverse pollinator seed mix of more than 30 types of native wildflowers and grasses
Funded by the U.S. Department of Energy’s (DOE) Solar Energy Technology office, the Photovoltaic Stormwater Management Research and Testing (PV-SMaRT) project from Great Plains Institute, DOE’s National Renewable Energy Laboratory, Fresh Energy, and the University of Minnesota 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 elevations, slopes, soil types, and geographical locations 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.
Site Background
Situated on 41 acres of agricultural land that previously had a rich, long tradition of dairy grazing, the 13-megawatt (MW) Eagle Point Solar project owned by Pine Gate Renewables is part of the company’s SolarCulture Initiative, which promotes sustainable agriculture, collaboration with communities, and research for intelligent solar development. In the early morning—and again in the late evening—the panels at this site sit about one meter above the ground, rotating to three meters above the ground at midday. This allows mowing equipment to pass through when the site needs maintenance, an essential aspect of maintaining quality habitat at solar sites.
After determining that experienced landscapers would be able to restore and maintain the groundcover, Pine Gate decided to make Eagle Point one of the first projects for the SolarCulture program. A flat site with clay soil and 16 inches of annual rainfall, this site’s PV-SMaRT monitoring equipment was installed in August of 2020 and will be in operation through August of 2022.
Pine Gate hired landscape design consultant Regenerate to come up with a vegetation plan, and Understory Consulting, an ecological consulting and restoration service nonprofit operating in Oregon and northern California, was chosen to develop a multi-year plan to seed the site with native flowers and grasses tucked underneath the site’s tracking photovoltaic (PV) panels in two-in-portrait configuration. The seed mix was developed by Sean and Kathryn Prive, who Maggie Graham, a researcher with Oregon State University and ecologist at Understory, describes as the “dreamers behind the project who led the restoration at the site.” The multi-year plan developed by the Prives is intended to restore the understory of the solar site to a native prairie and support native and domesticated pollinators.
Remarking on the site’s dual uses, Maggie mentions the support the site provides for both pollinator habitat and seed collection for the Rogue Native Plant Partnership. Facilitated by Understory, the Rogue Basin Partnership, and the Medford, Oregon, District Office of the U.S. Department of Interior’s Bureau of Land Management, the Rogue Native Plant Partnership focuses on increasing the diversity and availability of native plant materials in the Rogue Valley, a much-loved valley region in southwestern Oregon known for its wild and scenic Rogue River that runs from Oregon’s famous Crater Lake out to the Pacific Ocean.
When asked about challenges the team has run into at the site, Maggie offers a typical answer: “Weeds.” She adds, “Any time you’re trying to take a piece of land and modify the vegetation, weeds are a challenge.” Drought, too, has introduced some hurdles for the site to clear, as much as Maggie notes that “Drought in the west is ongoing, and normal to a degree.”
Despite the challenges, Maggie says, “It was especially neat to uncover what this site holds that had been obscured by previous vegetation. When we eliminated the weed pressure from a lot of the rhizomatous, introduced grasses—grasses that almost creep and grow quickly across a piece of land—we found a strong native seed bank and bulb bank at the site. This included a field of camas, which is a culturally important plant in the region.”
Additionally, the site boasts co-benefits unique to pollinator-friendly solar farms—honeybee hive hosting, native seed collection, and research, too. “This site in particular has a local beekeeper, John Jacob, on site who has expressed an appreciation for the late season forage that the site provides.” Jacob, owner and founder of Old Sol Apiaries and former president of the Southern Oregon Beekeepers Association, determined that Eagle Point would be an ideal location for his honeybee hives, and an agreement with Pine Gate ensured that Jacob could place a few dozen hives on the perimeter of the farm.
The shade from the site’s solar panels increased the abundance of flowers under the panels and delayed the timing of their bloom, which provides forage later into the season, Maggie says. She adds, “The native seed collection is especially unique—it’s wonderful to have enough seed production at one site to help support other ecological restorations. We’re fortunate to benefit from Pine Gate’s willingness to use this site for repeated research projects. This is one of four that I know is happening at Eagle Point.”
Research Process
As discussed in the 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 a test flood event of a certain magnitude—the higher the magnitude, the more intense the test storm. These tests help researchers and engineers to model and analyze rainfall and soil moisture, as well as to determine how fast excess water soaks into the ground during extreme storms.
Jake Galzki, a researcher with the University of Minnesota who is part of the modeling team for the PV-SMaRT project, says, “The Eagle Point site is the heaviest clay soil in the study, which is generally associated with lower infiltration rates. However, this site has a deeper crop rooting depth than some of the other sites, and Hydrus modeling showed slightly more infiltration than the shallower soils in the study. Approximately half of the 100-year design storm was infiltrated in the model simulations.”
Aaron Hanson, Energy Program Specialist at the University of Minnesota’s Institute on the Environment, says, “A key outcome of this project was to provide clarity on how solar farms and select ground cover impact storm water runoff at large-scale developments. This site is providing key insights to our model that in turn will help the solar industry, state and local governments, and communities understand the impacts and make better decisions.”
Based on the field research and modelling completed on this site and the other four sites across the country—New York, Georgia, Minnesota, and Colorado—the University of Minnesota team has also developed a stormwater runoff calculator. The modeling results from the calculator demonstrate that, under most site conditions, if soils are not compacted and deep-rooted vegetation is established, solar farms result in significant decrease in runoff compared to agricultural land uses. The calculator will be publicly available for use by local and state regulators, solar industry contractors and developers, and water quality advocates. GPI is modifying the interim best practice guide completed last fall to accompany the calculator and reflect the final modeling results.
Project Site Benefits
In the eyes of the project’s core team, the Eagle Point site presents some specific observations on another key aspect of the PV-SMaRT project’s focus: permitting. For reference, the federal government generally delegates administration of stormwater permitting, required under the Clean Water Act, to individual states. While based on a common foundation, state stormwater permitting processes will always reflect each state’s unique ecosystems and water quality priorities; therefore, solar projects must adapt to these differences.
Remarking on that adaptation process at the Eagle Point site, Brian Ross, vice president and project lead at Great Plains Institute says: “The Eagle Point site in Oregon gives us a West Coast example to demonstrate the national implications of the scientific findings, best practices, and final runoff calculator. Each state interprets the Clean Water Act regulations somewhat differently and looking at the Eagle Point site further demonstrates the applicability of the science across different regulatory and permitting regimes.”
Stakeholder Feedback and What’s Next
Like the other PV-SMaRT sites, data and observations from the Eagle Point site now serve as a benchmark as the project’s research team continues to gather insight about each of the five project sites across the country. Ongoing findings at the Eagle Point site further validate the project’s recommended best practices for solar developments and stormwater management: It is possible to help lower the soft costs 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 sustainable clean energy future that will benefit everyone for generations to come.
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, the second case study on SolAmerica Energy’s Georgia site, and stay tuned for updates on the project from Great Plains Institute. There will be a webinar talking about each of the three PV-SMaRT case studies this September—we invite you to join us! More details coming soon.
Photos
*Photo credit for all photos: Maggie Graham
African Company Provides Agrisolar Refrigeration
“A company called AkoFresh is providing solar-powered refrigerated storage that it says extends the shelf life of perishable crops from about 5 days to 21 days. This will boost seasonal income for farmers by more than $10 million, as well as reduce greenhouse gas emissions by 15%. Farmers can rent a space in the cold store for a daily fee of $0.30 per 20-kilogram crate of produce or take up a weekly subscription. They can also pay for the cold storage with crops instead of cash.” – World Economic Forum
Research Being Conducted at Pennsylvania Agrisolar Site
“In recent years, the environmental management of solar farms has become an exciting area of academic research, to assess how different practices affect the productivity of solar and agricultural enterprises and the land on which they operate. Two studies seeking to answer research questions around these topics are currently underway at Lightsource bp’s Nittany 1, 2 and 3 solar projects in Pennsylvania.
All three sites were designed and are being actively managed to boost biodiversity and support pollinator populations, in addition to generating clean energy for Penn State and their students. Lightsource bp seeded the sites with a mix specifically formulated by the American Solar Grazing Association (ASGA), in partnership with Ernst Conservation Seeds and Pollinator Service. The seed mix, aptly named ‘Fuzz and Buzz,’ was designed to support pollinator species at solar sites, in addition to flocks of sheep. At Nittany 1, more than 700 sheep are managing vegetation through rotational grazing, an example of agrivoltaics, or co-located solar and agriculture.” – Lightsourcebp
New Zealand Solar Farm Will Host Sheep
“Harmony Energy New Zealand has been granted approval to develop a solar farm in the Waikato which will generate electricity to power 30,000 homes as sheep graze underneath. The Environmental Protection Authority (EPA) has approved Harmony’s proposal for approximately 330,000 solar panels to be installed on 182 hectares of a 260-hectare site at Te Aroha West. The land will remain in the ownership of Tauhei Farms Limited, with livestock grazing continuing with sheep, rather than the current dairy herd.” –https://www.stuff.co.nz/business/300693453/hauraki-solar-farm-that-could-power-30000-homes-gets-green-light Power Technology
Two new reports funded by the U.S. Department of Energy Solar Energy Technologies Office highlight the potential for successfully and synergistically combining agriculture and solar photovoltaics technologies on the same land, a practice known as agrivoltaics. One report details the five central elements that lead to agrivoltaic success, while the other addresses emerging questions for researchers related to scaling up agrivoltaic deployment, identifying barriers, and supporting improved decision-making about agrivoltaic investments. Learn more about the reports’ findings.
The first report, The 5 Cs of Agrivoltaic Success Factors in the United States: Lessons From the InSPIRE Research Study, examines the Innovative Solar Practices Integrated with Rural Economies and Ecosystems (InSPIRE) project, which was funded by the U.S. Department of Energy (DOE) Solar Energy Technologies Office (SETO) starting in 2015. Over the past seven years, the project’s multiple phases have studied the co-location of solar with crops, grazing cattle or sheep, and/or pollinator-friendly native plants, and the resulting ecological and agricultural benefits.
According to InSPIRE research, there are five central elements that lead to agrivoltaic success:
- Climate, Soil, and Environmental Conditions – The location must be appropriate for both solar generation and the desired crops or ground cover. Generally, land that is suitable for solar is suitable for agriculture, as long as the soil can sustain growth.
- Configurations, Technologies, and Designs – The choice of solar technology, the site layout, and other infrastructure can affect everything from how much light reaches the solar panels to whether a tractor, if needed, can drive under the panels.
- Crop Selection and Cultivation Methods, Seed and Vegetation Designs, and Management Approaches – Agrivoltaic projects should select crops or ground covers that will thrive in the local climate and under solar panels, and that are profitable in local markets.
- Compatibility and Flexibility – Agrivoltaics should be designed to accommodate the competing needs of solar owners, solar operators, and farmers or landowners to allow for efficient agricultural activities.
- Collaboration and Partnerships – For any project to succeed, communication and understanding between groups is crucial.
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.
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.
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.
- Lead by UA, NREL, & SCF – Contact: gregbg@email.arizona.edu
- Pollinator Habitat Research to measure the growth and performance of pollinator habitat seed mixes and evaluate different cost-effective vegetation-establishment techniques.
- Lead by NREL – Contact: jordan.macknick@nrel.gov
- Pasture Grass Research measuring the growth and performance of dryland pasture grass seed mixes with different cost-effective seeding methods.
- Lead by NREL – Contact: jordan.macknick@nrel.gov
- 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.
- Lead by CSU – Contact: matthew.sturchio@colostate.edu
- 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.
- Lead by CSU – Contact: christopher.toy@colostate.edu
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.
“Last year, the horticulture staff at the Arnold Arboretum of Harvard University planted a new pollinator meadow at the Arboretum’s Weld Hill Research and Administration Building.
Wild-collected seeds of native perennials were sown beneath, between, and around an array of 1,152 solar panels, envisioned as an ecological and technological experiment. As these plants come into their own this season, the Weld Hill landscape champions two of the Arboretum’s key sustainability initiatives—increasing the capture and use of renewable energy and enhancing habitat for urban pollinators and other wildlife.
As plant life has proliferated across the field, so has the traffic of visiting insects. For example, an early morning walk past the arrays showcases the dauntless industry of thousands of bumblebees gathering pollen and sipping nectar. Bumblebees tolerate cooler morning and evening temperatures than many other pollinators. They rise early, work late, and even sleep underneath flower petals at night.
Now in its second growing season, the solar meadow at Weld Hill teems with more than 30 species of native, wild-collected flowers and grasses. This number will increase through additional plantings over the coming years. The variety of species sowed in the landscape ensures ready blooms for pollinators (and curious visitors) throughout spring, summer, and fall.” – Arnold Arboretum
Biological pest control and pollination are vital ecosystem services that are usually studied in isolation, given that they are typically provided by different guilds of arthropods. Hoverflies are an exception, as larvae of many aphidophagous species prey upon agriculturally important aphid pests, while the adults feed on floral nectar and pollen and can be effective pollinators of important agricultural crops. While this is widely known, the concurrent provisioning of pest control and pollination by aphidophagous hoverflies has never been studied. Here, we compared the potential of two aphidophagous hoverflies, Eupeodes corollae and Sphaerophoria rueppellii to concurrently control the aphid Myzus persicae and improve pollination (measured as seed set and fruit weight) in sweet pepper (Capsicum annuum). In a first semi-field experiment, aphid populations were reduced by 71 and 64% in the E. corollae and S. rueppellii treatments, respectively, compared to the control. In a second experiment, the aphid population reduction was 80 and 84% for E. corollae and S. rueppellii, respectively. Fruit yield in aphidinfested plants, was significantly increased by 88 and 62% for E. corollae and S. rueppellii, respectively, as compared to the control. In a separate trial, where the plants were not infested with aphids, yield increased by 29 and 11% for E. corollae and S. rueppellii, respectively, even though these differences were not statistically significant. The increase in seed set in the hoverfly treatments was statistically significant in both pollination experiments, i.e. independently of the presence of aphids. These results demonstrate, for the first time, that aphidophagous hoverflies can concurrently provide pest control and pollination services.
As the solar energy industry grows, many hundreds of thousands of acres of land will be transformed into solar panel facilities. With this large change in land use, there is the opportunity to promote biodiversity and support pollinators by using pollinator-friendly management practices at the solar facilities. This paper explores the ecological and economic effects of a pollinator-friendly solar facility compared to a turfgrass solar facility. The researcher hypothesized that a pollinator-friendly solar facility would be functionally equivalent in pollinator support and overall insect diversity to a pollinator-friendly non-solar field and that both sites would have far greater pollinator support and insect diversity than a turfgrass solar field. To test this hypothesis, vegetation and insect sampling were conducted and the resulting data were analyzed for differences in vegetative and insect diversity and pollinator abundance at a pollinator-friendly solar facility, a turfgrass solar facility, and a reference non-solar pollinator-friendly field. The diversity analysis revealed that the pollinator-friendly solar site was overall functionally equivalent to the non-solar pollinator-friendly site and the turfgrass solar site had low insect and vegetative diversity, but high insect abundance. Photovoltaic solar panel energy production is negatively affected by high temperatures. Therefore, to maximize energy production and promote biodiversity native forbs may be incorporated into a solar facility landscape to cool the solar panels by the cooling effect of transpiration and produce more energy than a traditional turfgrass landscaped solar facility throughout the growing season. Overall, this study supports the idea that pollinator-friendly landscapes could be more economically viable, as pertaining to energy output, and more ecologically beneficial compared to turfgrass. More research is necessary to further investigate and test the patterns seen at only these two solar sites, but these results are encouraging for the future widespread implementation of pollinator-friendly management practices in solar facilities across the Mid-Atlantic.
The push toward carbon-free and renewable energy sources has precipitated a nationwide (United States) trend to increase solar generation via ground-mounted photovoltaic (PV) arrays. Beyond carbon benefits, one possible way to provide additional ecological value of solar PV projects is to co-locate pollinator habitat when site conditions permit. Around 2015, the concept of a “scorecard” emerged that could assess the value of a solar project to pollinator species. The development and application of these scorecards, to date, has not been controlled by any central organization. Scorecards are being developed on a state-by-state basis using various processes, by a variety of subject matter experts, and using a range of oversight and review approaches. As such, there is variation between different state scorecard programs and divergent opinions regarding the scorecards themselves. Given that developing state and local laws and incentive programs are linked to the pollinator-friendly solar scorecards, it is important to consider the basis of the scorecards themselves. With interest in co-location of solar with pollinator habitat, this comprehensive study of existing pollinator solar scorecards considers the level of consistency across the scorecards, analyzes the specific scorable elements and their relative weighting, and investigates the factors that influenced scorecard development. A total of 15 state scorecards and one nonspecific scorecard available as of April 2021 were reviewed to identify common and differentiating features. A categorization system for individual scoring elements was created to facilitate numeric assessment across the available scorecards. Further, in order to understand the unique motivations and processes that influenced the design of the scorecards, interviews were conducted with 34 experts involved in scorecard design, policy development, and use, including university professors, state agency staff, and solar project developers, owners, and operators. Research uncovered a general lack of rigor, consistency, and oversight for scorecard design methodology, version control, and use. However, if the scorecards can be predictive of ecological outcomes – healthy pollinator habitat – then they may still be meeting their primary purpose. Field-based research is necessary to determine if there is a correlation between the points received on a pollinator-friendly scorecard and the actual solar PV site habitat conditions.
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