Picture 1. Solar panels powering the Solar Oyster Production System (SOPS) platform.

From filtering water to creating habitats for other marine species, oysters are a vital component of the Chesapeake Bay’s ecosystem. On land, they are the center of a rich cultural heritage as one of the region’s most valuable fisheries. Generations of families have made a living harvesting the bivalves, whose reefs were once so large that they posed navigational hazards for ships traversing the Bay. However, decades of pollution, disease, and overharvesting have devastated the oyster population. Modern restoration efforts and harvesting regulations offer a glimmer of hope for the bivalve, and Solar Oysters is making a big impact with its revolutionary oyster-production platform powered by solar.

Prior to the establishment of Solar Oysters, the idea to create a floating solar array came to Mark Rice, President of the Baltimore-based engineering firm Maritime Applied Physics Corporation (MAPC), while he was working on a project on the Chesapeake Bay. A local power plant utilized Chesapeake Bay water to cool the plant, and there was a growing interest in mitigating thermal discharge into the Bay. Rice and his team decided the best course of action was to remove incident solar energy from the water to offset the thermal effluent. They knew solar panels would generate valuable electrical energy while also helping to keep water temperatures down and began designing floating solar platforms to tackle the problem. As they were planning the floating arrays, they realized a source of ballast was needed to weigh down the systems and found an opportunity to help improve oyster aquaculture in the Bay simultaneously. Led by Steve Pattison, the environmental strategy firm EcoLogix Group collaborated with MAPC to provide valuable insight about stakeholder engagement, local aquaculture, siting, and environmental permitting. The two companies formalized their relationship in 2019 with the launch of Solar Oysters LLC. By October 2021, Solar Oysters had raised enough money through private funding to construct the first Solar Oyster Production System (SOPS) prototype—a floating high-density oyster-production system automated through solar energy—in Baltimore Harbor.

Picture 2. Graphic design of the SOPS prototype.

Measuring 40’ by 25’, the platform has 12 375-watt solar panels attached to the roof capable of generating 36 kWh, alongside four on-board batteries with a 14.4 kWh storage capacity. The solar array powers a system of five vertically rotating ladders on timers, each consisting of 23 rungs capable of holding up to five oyster baskets per rung. This provides a maximum capacity of 575 baskets. As the ladders rotate, the oysters are exposed to different water quality parameters, including temperature, salinity, and dissolved oxygen, resulting in uniformity among all ladder basket positions. At the top of the rotation, the baskets are completely out of the water and exposed to sunlight before resubmerging as the next rung peaks. A manual spray wash system is mounted onboard and pulls water directly from the Bay, allowing those tending the platform to clean the baskets and oysters as needed.

Picture 3. SOPS ladder system
Picture 4. Platform manager Emily Caffrey with an oyster basket from the ladder system.

Compared to traditional oyster farming methods, the SOPS platform brings a technological advancement to an industry that has not changed considerably in decades. On farms where the oysters are grown at surface level in floating cages, workers must manually flip each cage over to prevent biofouling. Biofouling refers to the accumulation of organisms such as algae, barnacles, or mussels on the oyster shells and equipment, thus impeding the growth of the oyster population. SOPS greatly reduces the manual labor needed to keep the oysters healthy, thanks to the rotating ladders and spray system. Moreover, the system’s vertical design drastically increases the number of oysters produced per acre. While a traditional float farm may produce between 250,000 and 400,000 oysters per acre, SOPS can produce up to 250,000 oysters on one 0.02 acre-sized barge. This small footprint is an advantage in securing permits or leases compared to a traditional farm that often requires permitting several acres.

Solar Oysters’ first growing season was in partnership with the Chesapeake Bay Foundation as a participant in the Baltimore Harbor oyster gardening program. A grant from the Abell Foundation afforded Solar Oysters the opportunity to onboard spat-on-shell oysters in the fall of 2021. After the 2022 growing season, about 40,000 oysters were transplanted to the Chesapeake Bay Foundation’s sanctuary reef at Fort Carroll, where they significantly helped to advance the Foundation’s oyster-restoration efforts. That same day, Solar Oysters accepted an additional 490,000 spat-on-shell oysters for the upcoming 2023 growing season. Concurrently, seed oysters were being grown to evaluate the effectiveness of the SOPS technology for the oyster consumption market, onboarded at the same time as the first spat-on-shell cohort. After 12 months of growth, the seed oysters measured between 2.5 and 3 inches in length, a size that could take 18 to 24 months to reach using traditional growing methods.

Picture 5. Seed oysters.
Picture 6. Spat-on-shell oysters.

Solar Oysters’ goal is to develop, manufacture, and sell the SOPS technology to organizations focused on oyster restoration or growing oysters for market. In 2023, they plan to continue research on the SOPS platform as they narrow down the best practices for growing oysters on the prototype. Other improvements to the system will include installing a semi-automated spray wash system that replaces the current manual one onboard. The 2023 season will also see Solar Oysters continue to contribute to restoration efforts in the Chesapeake Bay. With such an encouraging first growing season of both spat-on-shell and seed oysters, the technology has the potential to address environmental concerns while also modernizing oyster aquaculture for growers in the Chesapeake Bay and beyond.

All photos courtesy of Solar Oysters LLC.

Sunstall, a California-based solar installer, is helping farmers harvest the sun twice with their new vertical solar system, known as Sunzaun. The Sunzaun vertical solar system was originally engineered by a company in Germany. After seeing successful installations of the product in Europe, Sunstall decided to bring the design to the United States. The market for agrivoltaic installations in America is growing, but one of the biggest barriers is tied to land use. Concern about installing solar on valuable agricultural land is common, and often increases as the solar system’s footprint increases. Traditional solar installations use a racking system to secure solar modules, which are then tilted to the appropriate angle on a horizontal axis. These tilted systems require a larger amount of land compared to vertical systems. Sunzaun is installed in a portrait orientation between two piles with no racking system involved. The minimalistic design uses holes in the module frames for a simple attachment to the piles without the need for a heavy racking system, while the bifacial modules themselves allow both sides of the panel to produce energy.

Sunzaun’s portrait orientation allows adjustments to be made more quickly during later stages of a project. In systems designed with a landscape orientation, the rails used to mount panels onto the racking system are cut to fit the expected panel size. Should the size of the panel change after all other components have been finalized, the project may be delayed significantly while the rails are reengineered to fit the updated panel size. Thanks to Sunzaun’s unique design, it is easy to adapt to a change in panel size by simply adjusting the distance between each pile. It is even possible to adjust the height of the panels from the ground if needed.

Completed in 2022, the first Sunzaun installation in the United States is located on a vineyard in Somerset, California. Although the vineyard owner already has rooftop solar on the property, an interest in new solar developments and agrivoltaics led to a new system within the rows of grapevines. Composed of 43 450-watt modules connected to a microinverter and two batteries, the Sunzaun system sits on a hillside between rows of grapevines. Only one row of vines needed to be removed to make room for the system, and harvesting equipment is still able to work in the field directly next to the Sunzaun. While it is too early to say for certain what additional benefits the Sunzaun may provide beyond on-site power generation, the benefit of preserving grapevines alone is a significant win for the winery.

As the United States continues to take steps to combat climate change, innovative solar system designs are more important than ever. The Sunzaun’s streamlined design reduces the time it takes to get agrivoltaic projects off the ground. When you factor in the ability to save valuable crops and viable land with a vertical system, the minimalistic approach that Sunzaun offers farmers becomes even more appealing. A successful growing season at the Somerset vineyard will hopefully reveal even more benefits to installing this promising product and encourage others to consider the value of a vertical solar installation as well.

All photos courtesy of Sunstall Inc.

When it comes to conversations surrounding energy and water use in the modern world, the agricultural industry’s consumption of both is often at the forefront. As the world’s population continues to grow, humanity is tasked with the challenge of finding ways to meet both food and energy demands across the globe. “I really believe that greenhouse growing is the epitome of sustainable agriculture,” says Soliculture cofounder and CEO Dr. Glenn Alers. Whether it is the ability to greatly increase crop yields when compared to traditional open field growing, or the potential for increased water-use efficiency in combination with hydroponics, greenhouses could play a key role in addressing these concerns. Solar greenhouses also could also play a role in mitigating future energy crises. 

Soliculture began in 2012 as a startup in the Physics Department at the University of California Santa Cruz. Dr. Alers and his cofounder were conducting research on luminescent solar concentrator panels when he realized the technology’s agricultural potential. Luminescent solar panels utilize a luminescent dye that selectively absorbs a portion of the solar spectrum and readmits light at a different wavelength. The dye used in Soliculture panels absorbs the green portion of sunlight with low photosynthesis efficiency and converts it to red light with much higher photosynthesis efficiency. The panels enhance the light quality inside a greenhouse by optimizing the light spectrum for improved plant growth. Moreover, the panels contain bifacial cells that collect the light reflected from the crops planted below them. The red luminescent dye also enhances the power output of embedded cells by 15 to 32%, compared to a conventional panel. 

Installed Soliculture luminescent solar panels.

In 2019, Soliculture began a research project on Whiskey Hill Farms in Watsonville, California, aimed at developing these solar panels for use on hybrid high-tunnel greenhouses. As an active organic farm already growing produce in both field and greenhouse settings, Whiskey Hill Farms served as an ideal host for the project. The Soliculture research greenhouse was constructed from the ground up with help from a local high tunnel installer, measuring 120’ long and 25’ wide upon completion. Additional bracing was added to the roof structure, forming a “queen style” truss to support the weight of the panels. One half of the high tunnel was covered by a semi-clear plastic film that served as the control for the upcoming crop growth study, and the other was covered by Soliculture solar panels. These panels were specially designed for high tunnel greenhouses and had a cell coverage of 42%.  

Interior of research greenhouse with panels installed.

The project hit a temporary snag when waterproofing the panel racking system proved to be more of a challenge than expected. At first, horizontal mounting bars were attached to the tubing of the greenhouse’s roof frame and foam weather stripping was installed between the panels to create a watertight seal. Water was still able to leak through at the corners and where the mounting bolts connected the panels to the roof. Knowing the potential for these leaks to cause erosion and negatively impact crop growth, the Soliculture team returned to their laboratory and created a modified racking system specifically for high tunnel application. This new system used mounting brackets that attached to the bottom of the frame and utilized a rubber “T” gasket inserted between the panels to create a seal. Finally, the plastic film portion of the roof was attached to the panels using an aluminum channel screwed into the panel frame and “wiggle wire” to hold the plastic film in position. With a waterproof roof in place, the crop trail was ready to commence.  

The following crops were selected for planting following the completion of the high tunnel in mid-November: strawberries, red romaine lettuce, red butter head lettuce, cilantro, mustard greens, and turmeric. To ensure the trial’s results would translate to commercial production, the research team used common commercial growing methods throughout the duration of the trial. These methods included drip irrigation with untreated well water, sand filtration, and liquid organic fertigation. By the end of the trial, the majority of the crops grown under Soliculture panels matured close to two weeks ahead of those grown under the clear film portion of the high tunnel. The fresh weight for the under-panel crops was superior as well, with red butter head lettuce seeing the greatest benefit at 145% higher weight. Mustard greens weighed in at 95% higher, cilantro at 35%, romaine lettuce at 32%, and turmeric at 25%. The strawberry fruit showed no statistically significant difference in fresh weight, but the single 5’ by 120’ planted bed yielded more than 350 pounds of fruit by the end of July.  

Crops grown under Soliculture panels.
Crops grown under plastic film.

On top of the very successful crop trial, the power generated by the greenhouse panels was used by Whiskey Hill Farms to power their day-to-day operations. A total of 58 Soliculture panels provided the farm with a 6kW system, which was connected to an inverter. The AC power was then fed back into the farm’s power system, a testament to how greenhouse solar can benefit the farm beyond improving plant growth.  

The field of agrivoltaics is constantly evolving, with numerous researchers and farmers searching for the ideal nexus between the agricultural industry and energy production. Soliculture’s contributions to agrivoltaics is important for farmers who have reservations about growing food underneath and around solar panels. “We haven’t seen any negative effect on plant growth,” Dr. Alers says, referring to the Whiskey Hill Farms project and several other successful Soliculture installations across the United States and Canada. Greenhouse production has always had the potential to help alleviate the water crisis and increase the amount of food grown per acre, but Soliculture’s technology is giving it a bright future in energy production, as well. 

All photos courtesy of Soliculture 

Written By: Alex Delworth, Clean Energy Policy Associate; Center for Rural Affairs

Just off the campus of Maharishi University in Fairfield Iowa, sits a 1.1-megawatt (MW) solar farm. Beneath the panels, a flock of sheep and their newborn lambs are grazing, while beginning rancher Emily Mauntel and her Australian Shepherd Ziggy stand back and admire their work.

Solar farms pose a considerable opportunity for multipurpose agricultural uses in rural spaces. Iowa has seen a rapid increase in solar project development the past two years. According to the Solar Energy Industries Association, the industry is expected to add another 1,304 MW—a 250% increase over current installed capacity—during the next five years. Depending on the type of technology installed, this could mean between 6,520 and 13,040 acres of land will be used for solar production. With proper local siting, these projects will be required to plant and maintain native vegetation underneath the panels. This increase in open pasture presents a unique opportunity to combine traditional land uses with renewable energy development, such as pollinator habitats or open grazing for livestock. An opportunity Emily has already begun benefiting from.

Originally from Michigan, Emily relocated to Fairfield to attend Maharishi International University. While completing a three-month internship at a goat farm in Oregon as part of the university’s Regenerative Organic Agriculture certificate program, her interest in livestock grew. After the internship, she remained in Oregon for another year, working for various livestock operations and gaining experience in the industry. In late 2021, she moved back to Fairfield to work on the university’s vegetable farm and help her peers in their respective livestock businesses.

Emily Mauntel holding a solar-grazing lamb. Photo: Emily Mauntel

One day she and a friend were driving past a large solar array in Minnesota and noticed how the infrastructure was perfect for sheep grazing. They knew about the array in Fairfield, which is owned by the university and operated by Ideal Energy, a local solar company. She contacted the solar company to pitch the idea first and gained their approval before approaching the university. Both parties were ecstatic because the university had been looking for somebody to graze livestock and Ideal Energy saw an opportunity to avoid spending about $5,000 for annual landscaping, according to the company. Emily said the two parties came to an agreement that she would graze the array, which provided her an opportunity to access pasture in exchange for landscaping the solar farm. With this agreement, Emily benefited by not having lease payments for the time her sheep were on the farm, saving her approximately $360 per month according to Iowa State University’s land lease estimates, or about $2,520 for 2022.

Sheep grazing under solar array. Photo: Emily Mauntel

Once Emily had approval, she and her friend went into business together and purchased a 30-head herd of sheep from an auction in Texas. In May 2022, 29 ewes and one ram were dropped off on the six-acre, 1.1-MW solar farm. Before purchasing the herd, she surveyed the land and determined that, given the amount of growth on the site, she would be able to graze five sheep per acre. That is two more than usual because of how lush the plant life was on the property. The site was planted with a mix of flowering prairie species, including clover, fescue, broad-leaf plantain, and others, which served as a good food source. The sheep were allowed to roam freely throughout the solar array, something Emily said worked well. Overall, she believes rotational grazing would have been more efficient but would have required a larger investment due to the cost of a moveable fence.

Emily with her herd. Photo: Emily Mauntel

What makes this story especially interesting is that the agribusiness model directly addresses two major issues beginning farmers face—access to land and infrastructure. A 2017 survey by the National Young Farmers Coalition found that land access was the number one issue their respondents faced. Young farmers, according to the survey, are also the most inclined to rent, which makes finding land with the right infrastructure more difficult.

The Fairfield solar site’s infrastructure made the land even more attractive to Emily. She said it had sufficient fencing to hold her sheep and keep out predators. Due to the required native vegetation management, it also had plenty of food for the sheep, which means she never had to supplement food for them, except a mineral feed mix for nutrition. A water source to fill up the livestock troughs and an access road straight up to the gate also proved beneficial. Considering all of these factors, Emily was able to cut a lot of costs throughout the process.

Newly energized by the experience she has gained through solar grazers and managing her own livestock, Emily is now looking to return to the West to continue ranching. She and her business partner plan to sell their herd. Emily hopes to see the solar grazing model continue on the site, saying it has been a perfect opportunity for her to gain experience in the industry, and she believes it will be a great opportunity for the next person, as well.

Photo courtesy of Far Niente Winery

At Far Niente Winery, respecting the land and all it provides is just second nature. Since 1979, their winemakers have been coaxing award-winning wines out of the grapes grown on their Napa Valley estate, but in 2005 began embracing their role as environmental stewards through their sustainability practices related to farming, winemaking, and renewable energy generation. Located on the Martin Stelling Vineyard in Oakville, Far Niente’s floatovoltaic system is at the forefront of the winery’s commitment to those sustainable practices and ethical winemaking.  

When Far Niente decided to go solar, they faced challenges both unique and common to the agricultural world. Where many businesses may have chosen to place panels on the roof of their buildings, Far Niente’s old stone winery building is on the National Register of Historic Places, making it impossible to do so without violating regulations. Installing ground-mounted panels immediately around the heritage building was not an appealing solution either. After doing the math and realizing they would need to install over 2,000 panels to hit their energy production goal, they were faced with a tough choice: remove established cabernet sauvignon vines or get creative and take a risk. “Taking two acres out of cabernet production really hurts,” says winemaker Greg Allen. “By looking to the pond, it allowed us to maximize how many grape vines we were able to keep and still meet our goal.” These challenges ultimately culminated in the decision to build the world’s first grid-connected floating solar array, despite the lack of real-world success stories of floatovoltaic arrays at the time.  

Developed by Thompson Technology Industries and installed by SPG Solar, the ambitious project went live in April 2008. A total of 1,000 Sharp 208 polysilicon panels were installed over the vineyard’s pond, covering just shy of a full acre. The panels rest atop pontoons anchored to the pond’s banks via marine-grade cabling attached to concrete columns. This setup allows the pontoons to rise and fall with changing water levels throughout the year. Rounding out the vineyard’s solar system are 1,300 ground-mounted panels adjacent to the pond. The system was originally installed with a 500-kilowatt central inverter, but that was replaced after 10 years with 12 SolarEdge string inverters. Together at peak output, the arrays generate roughly 407 kilowatts total with about 177 kilowatts coming from the floatovoltaic system alone. 

Photo courtesy of Far Niente Winery

Unsurprisingly, building such a system comes with a substantial financial commitment. The project’s total cost was $4.2 million upon completion, with an estimated payback period of 12 to 15 years. Fortunately, the net cost for Far Niente was significantly less, thanks to a $2.80/kW self-generation cash rebate from Pacific Gas & Electric, as well as a 30% federal tax incentive and accelerated depreciation tax benefit. The winery worked with Banc of America Leasing and Capital on a seven- year lease as well, which included a buyout option that would allow them to be the sole owners of the system. Far Niente did opt to purchase the array at the end of the seven years, and reports that the system paid for itself at around year 14 of operation.  

With all the energy generated by the system, the winery is able to cover about 80% of its annual energy requirements, but that is far from the only benefit. The floatovoltaic array saves almost a full acre of viable land from being sacrificed for additional ground-mounted panels. Since this part of the vineyard is foundational to the winery’s cabernet sauvignon program, all that preserved space equates to thousands of dollars of bottled cabernet sauvignon revenue saved each year.  

Additionally, there’s reason to believe that the panels’ positioning on top of the pond leads to increased efficiency when compared to the ground-mounted panels. Greg Allen has taken the surface temperature of the panels and found that those on the floating array can measure up to 5 degrees Fahrenheit cooler than their land-based counterparts. Because photoelectric conversion improves in cooler environments, keeping the solar panels at a lower temperature will increase the energy production efficiency when compared to the warmer panels on land.  

A further boon to resource management is the array’s potential to reduce evaporation rates — a crucial win for a vineyard operating in an area seeing increasingly higher temperatures and more frequent drought conditions. While Greg notes that there is no completed study yet, he says, “In my mind, I think that the panels decrease the amount of evaporative loss from the pond.” He adds that it is difficult for the winery to quantify the potential amount of water saved, since there are systems both pulling water from and pushing water to the pond at various times. Currently, the pond serves the winery in several capacities, including as a fire- and frost-protection system, irrigation source, and as the recipient of all process wastewater from the winemaking facility. Three wells intermittently feed the pond, as well. Greg states that there is an ongoing research partnership between the winery and University of California Davis that will hopefully shed light on the shading and water conservation benefits, as well as the ecological impacts of the array.  

When reflecting on the challenges the project presented, Greg says “Interconnection [to the grid] was a big one.” In order to meet their energy production goals, the entire system needed a 500-kilowatt inverter. The winery hit a roadblock with the project when they realized the main service transformer for the winery was only half that size. Far Niente’s utility provider requires that the main service transformer must be able to accommodate 100% of the energy produced by a solar system. “That spawned a massive project of its own,” Greg says, since the winery then had to replace their transformer to match the power rating of the inverter before they could bring the array online.  

As the system approaches 15 years of use, they are noticing more individual panel failures. Greg says that the panels installed in 2007 are no longer commercially available to replace the failed panels, but there is a silver lining. He estimates around five more years of operation with their current set up, and then the winery could begin to look at the possibility of a major system overhaul. Over a decade of research and development has greatly increased the efficiency of today’s panels, providing the possibility of cutting their solar array footprint in half while maintaining the amount of energy produced on-site. “We could regain substantial amounts of vineyards,” he says. Should the winery choose to overhaul their entire system in such a way, the future revenue from the potentially recovered vineyard space could fund the cost of the improved system. 

Photo courtesy of Far Niente Winery

Looking back, Greg says a big challenge has been on the operations and maintenance side of owning the arrays. “Our main job is making and selling wine, and suddenly we’re put in the position of having to – on a daily basis – verify that the system is functioning and then initiate troubleshooting” when it’s needed. He points out that in the beginning, no one at Far Niente was an expert at what essentially became running a small power plant, but they had to develop that expertise in order to keep the system operating. With the possibility of a new system installation on the horizon, Greg speculates that partnering with a third party on a power purchase agreement could be an ideal solution for Far Niente. A power purchase agreement is an arrangement that allows a solar developer to install, operate, and own a system on a customer’s land. The customer is then able to purchase the electricity generated by the system directly from the developer, often at reduced rates. “It means that we would have on-site generation of renewable energy that we use,” he says, “and we would rely on the experts to maintain the system while we focus on growing grapes and making phenomenal wine.”  

No decisions have been made yet as to whether Far Niente will pursue upgrading their system or move towards a power purchase agreement. Regardless of what path the winery will take in the coming years, Greg says they are really pleased with their decision to pursue onsite renewable energy generation and the overall performance of the solar arrays over the years. In particular, the winery’s ownership and staff have enjoyed being pioneers in the field of floatovoltaics. Far Niente’s years of renewable energy generation serve as an excellent example of how solar energy production can support a company’s efforts to implement sustainable measures while existing in harmony with agricultural operations.

Photo: AgriSolar Clearinghouse

The South Deerfield dual-use array is a research facility built at the University of Massachusetts (UMass) Crop and Animal Research and Education Farm. The pilot project is the result of a team leveraging private, public, and governmental resources. Designed and constructed in 2010 by Hyperion Systems, a solar development company based in Amherst, Massachusetts, the UMass South Deerfield site is the oldest example of agrivoltaics in the United States. At the time, dual-use racking was not commercially available, so the Hyperion Systems team developed a custom solution. With guidance from UMass Amherst agronomist Dr. Stephen Herbert, the team began testing shading implications using 2x4s and plywood. The initial goal was to determine ideal shade conditions to grow hay grasses below the array while maintaining flexibility for future research opportunities.

Photo: Hyperion Systems

The array is fixed-tilt and south-facing with module heights ranging from 6 to 8 feet to the leading edge. The panels are spaced at a range of 2 to 5 feet (E-W) edge to edge, which supports a wide range of crop productivity investigation under varying panel configurations.

Photo: Hyperion Systems

For the first five years of the array’s existence (2010 to 2015), the field beneath the panels was used for cattle grazing. The beef cattle enjoyed the shade provided by the modules during the warm summer months and were able to scratch against the racking posts without damaging the array. The electrical components were housed in protective conduit to ensure animal and farm labor safety. Dr. Herbert found that the grass underneath the panels, the variable group, grew 80 to 90% of the yield compared to the grasses in full sunlight, the control group. What’s more, the team found that if the modules were raised above the cattle’s head height and the structure was built beyond the minimum local building code requirements, the racking could withstand interference from large grazing animals.

Photo: Hyperion Systems

Since 2016, the array has been used for crop research. UMass South Deerfield has been a part of the NREL InSPIRE Project for three rounds (2016 to 2019, 2019 to 2022, and 2022 to 2025). Various crops have been studied during this time, primarily broccoli, bell peppers, kale, and Swiss chard. Other crops such as snap beans were grown for one season. In addition to crop trials, diverse layout configurations have also been explored. This includes growing the crops north to south and east to west directly beneath the modules, and in full sunlight between the panel rows. It’s clear from Dr. Herbert’s research that the crops under the panels benefit from the shade provided during drier growing seasons, like in 2016 and 2020, where the variable group did as well or better than the control group in full sunlight.

Photo: Hyperion Systems

The UMass South Deerfield dual-use array is a landmark project in the history of agrivoltaics in the United States. It continues to provide valuable insight into the viability of crop co-location in New England and beyond.

Photo: Hyperion Systems
Photo: Hyperion Systems

The Joe Czajkowski Farm project will be a commercial agrivoltaic array in Hadley, Massachusetts, set to be completed in time for the 2023 growing season. The project was developed through a partnership with Joe and Hyperion Systems, Amherst, Massachusetts, which has a long history in agrivoltaics. The farm’s dual-use array will serve as an excellent example of a medium-scale solar site that works for both the farmer and the land.

Farm owner Joe Czajkowski is a third-generation Hadley farmer. He produces on more than 400 acres across the Pioneer Valley. The farm practices both organic and conventional farming, contributing to the local food system by providing produce to institutions and retail outlets, including UMass Amherst Dining Services, Springfield Public Schools, Trader Joe’s, Whole Foods, and numerous local restaurants. Czajkowski’s produce reaches Boston almost daily, and their squash noodles can be purchased up and down the East Coast.

Czajkowski has been growing on this specific parcel for over two decades, rotating a variety of crops, including beets, broccoli, tobacco, and corn silage, among others. While the parcel is used annually, it is not one of their most productive fields. The site is set back from the roadway, has an existing farm access road, and features screening trees from neighbors. Combined, these conditions make the site an ideal space for an agrivoltaic system.

The project will consist of a 450-kW DC solar array on 2.2 acres. Comprised of 850 modules, the array will utilize single-axis tracking. Modules will be 10 feet above the ground when the modules are horizontal. These system specifications meet the Massachusetts SMART Program guidelines for agrivoltaics. The rows will be spaced 26 feet post to post, allowing for equipment to make two or three passes between the post rows, depending on the farming activity. In the first year, Czajkowski intends to grow broccoli underneath the array. He will rotate crops in the second year and plans to grow zucchini squash.

The array is part of a UMass Amherst-led research project that will assess crop productivity, soil health, and microclimatic conditions. The project has been awarded funding by the U.S. Department of Energy’s Solar Energy Technology Office. Data will be gathered by scientists from UMass and American Farmland Trust.

As an innovative business owner and farmer, Czajkowski is looking forward to the research opportunity with his alma mater UMass Amherst. The dual-use array will increase the farm’s economic viability by diversifying operations. Czajkowski is excited about the opportunity to be an energy provider for his community.

In partnership with Lightsource BP, Texas Solar Sheep grazes over 1,800 sheep on a solar site in Deport, Texas. These sheep are grazed in groups of 50 to 75, 250 to –270, and even 500, making Texas Solar Sheep one of the largest Agrisolar grazing operations in the United States.   

All 1,800 sheep are grazed and managed on one solar site, which has 18 individual pastures. The sheep are grazed year-round on the same site. The area gets maybe one snowfall a year, which is not a huge issue for them, as the solar panels provide good protection from elements for the sheep. The farm may buy one stockpile of hay for the winter if they feel it is necessary as a precaution, but stockpiling food is not a great concern on this operation.  

No mowing duties are required on this site, thanks to responsibly managed, rotational grazing of the sheep. There are many weeds that sheep will not eat, so they must be manually removed. After some time, if those weeds can be removed from the site, then there is no need for mowing or the use of gas or diesel-operated maintenance equipment. Graziers mowed this site four times in 2021 and have not mowed at all in 2022 as of the end of September.  

J.R. Howard, owner of Texas Solar Sheep, says it is important for new graziers to know that the client of this operation is the solar site, and the grazier is providing a service to replace mowing on the site. The sheep-grazing service has been shown to provide significant benefits to the solar site, including enhancing the health of the turf, reducing runoff from rainfall, and providing crucial shade relief to both the grasses and the sheep during drought periods like those seen in 2021.  

Photo courtesy of Texas Solar Sheep

Healthy Turf Prevents Runoff 

The site has realized benefits from preventing rainfall runoff as a result of developing healthy turf. There was hardly any runoff after 3 inches of rainfall, due to the enhancement in turf quality from responsible grazing management, according to Howard. Healthy turf is a result of not overgrazing individual areas and managing proper sheep rotation. The sheep are not allowed to eat to the bare ground, resulting in what is known as a healthy turf that allows the land to capture and hold the water when it rains, resulting in less runoff and other associated issues. Howard said the land is back to looking like “normal land” and not “golf courses.” 

Shade Relief for Grasses and Sheep 

During the drought of 2021, the solar panels provided crucial shading for the grasses and the sheep. The grass between the panels that did not have shade did not do as well as the grasses that were getting shade from the panels. “The shade support really helped a lot,” Howard said.  

Sheep typically feed in the morning and then hang out in the shade during the day, which the panels provide plenty of. Unlike goats and cattle, sheep do not damage equipment by rubbing against it, climbing on it, or chewing on wires as some goats do. The sheep can be comfortable under the panels during the day with little, if any, threat of damage to equipment. 

Rotational Fencing  

One challenge that the operation has dealt with is constantly rotating the sheeps’ pasture, which needs to be consistent and on schedule. Limiting grazing to smaller areas more often, as opposed to one large area less frequently, is ideal. However, this approach requires fencing that must be moved regularly. The operation requires “cross fences” to break large blocks of land into smaller pastures. Moving fences is one of the most consistent tasks of the operation, but it is manageable.

 

Photo courtesy of Texas Solar Sheep

Breeding for Agrisolar Conditions 

The solar company allows the sheep owners to breed lambs when they want. The sheep live on the solar site from birth until they are sold or pass away. The sheep are also checked by a veterinarian at various times during their life cycle on the site. Owners breed sheep on site, to “get the ewe they want,” Howard said.  

This selective breeding process is an attempt to breed a sheep genetically superior in parasite resistance than previous generations of sheep. These sheep would be specifically resistant to parasites during the lamb phaseand the lactating ewe phases of their life, which are often when farmers struggle with parasites infecting their sheep. Due to the selective breeding process on this site, the sheep will be more resilient to the conditions they experience in Texas, which includes hot temperatures and prolonged, wet conditions. 

Although Dorper sheep, which originated in South Africa, are genetically capable of handling hot temperatures, they are being breed with Katahdin and St. Croix to enhance their genetic capabilities further—making them the most ideal sheep for agrisolar operations in these climate conditions. 

Photo courtesy of Texas Solar Sheep

What New Graziers Should Know 

New graziers should know that this is not a grazing lease with the solar company but, rather, a grazing service business. As a service business, people with sheep will have a customer that they are providing a service to. This requires graziers to spend more time on-site where they can correct issues quickly. If sheep get out of the fenced paddocks, graziers can get them back to their assigned areas quickly. Sometimes sheep pass away and need to be removed as quickly as possible. Being on-site allows for that. If sheep are sick, they can be attended to quickly. The grazier can also ensure that sheep have constant access to water.  

The solar company also benefits from having Texas Solar Sheep staff on-site regularly. “We are out there more than the solar folks, so we see issues for them, too. It has been an extra set of eyes for them on the solar equipment, so that has been a significant help for them, as well. If they see downed panels, damaged wiring, or even fires, they can report it quickly and get it taken care of,” said Howard. “There is a public eye on this stuff, so we want to make sure we are doing it right.”  

Howard stated that grazing is the future of utility-scale solar. It is important that the first few big sites get it right. With great partners like Lighthouse BP, Texas Solar Sheep has been able to scale up its operation, and is planning for larger sites for the future, meaning more sheep on more solar sites. 

Howard said the family farm had about 300 ewes and having the opportunity to partner with Lightsource BP has allowed them to have extra land to graze and scale up their operation. “We’re not a big landowner, and this allowed us to scale up a lot, to 1,800 ewes.” 

All photos courtesy of Sandbox Solar

Agriculture Type: Specialty greenhouse farming

Project Type: Small commercial net-metering agrivoltaic system

Project Size: 26.7kW-DC

Project Design: Solar fence structure, SolarEdge inverters, 72-cell bifacial solar panels

Location: Fort Collins, CO

Developer and Contractor: Sandbox Solar

Summit Plant Labs is a specialty crop farm using greenhouses and lab space to grow pristine crop starts, microgreens, and other specialty crops. In their greenhouses they noticed they were having detrimental edge effects where plants growing along the edges are exposed to higher sunlight, heat, and less moisture. They hired Sandbox Solar to create a strategic way to solve these issues using solar panels to create shade at the edges and generate power.

Sandbox Solar used its SPADE Agrivoltaic Design Tool to generate 3D visual renderings and irradiance simulations of the greenhouses. SPADE effectively provided the farm with the necessary information to determine the optimal design that would produce a significant amount of energy to offset their consumption while also providing effective shading tactics to solve the edge effects and improve their agricultural business.

Example output from SPADE – Agrivoltaic Design Tool

The system was installed in September 2022, led by project manager Danny Weaver. The Sandbox Solar team customized the racking system with Tamarack Solar Products and other custom-engineered products. The system is vertical with the top edge approximately 9’ high and bottom at about 28” above grade. The height is customizable, and the metal is galvanized to protect it from external elements. This bifacial solar fence was installed using concrete piers; however, rammed-steel profiles would be the preferred installation method for future projects. The vertical mounting of the panels allows for energy to be collected from the front and rear sides of the panel. The irradiant reflection of the greenhouse covering provides a boost in production during dawn and dusk. This agrivoltaic system can be applied to open fields and other applications.

The production profile is unique and ultimately could provide a means for balancing the duck curve, a name given to a typical energy demand profile throughout the day, where demand is highest in the mornings and evenings and lowest during the mid-day, giving the trend a duck-shaped appearance. Production and evaporation data is still being collected (as of October 2022).

Summit Plant Labs energy-production profile

For more details on this project, check out this video:

For more details on SPADE, visit the Sandbox Solar website:   

https://sandboxsolar.com/agrisolar-tools/

All photos courtesy of Sandbox Solar

Agriculture Type: Specialty crop research farming

Project Type: Small commercial net metering agrivoltaic system

Project Size: 11.4kW-AC

Project Design: Solar pole mount structure, SolarEdge Inverter, 72-cell bifacial solar panels, 72-cell opaque polycrystalline solar panels, thin film 40% semi-transparent solar panels

Location: Fort Collins, CO

Developer and Contractor: Sandbox Solar

Sandbox Solar is a solar energy developer and Engineering, Procurement, and Construction (EPC) company located in Fort Collins, Colorado. The company installs over 1MW of solar annually and has conducted agrivoltaic research and development since 2018 in a joint effort with Colorado State University.

Sandbox Solar received a USDA Small Business Innovative Research Grant, Phase I. This grant funded the design and development of the novel agrivoltaic research plot located at Colorado State University’s Agricultural Research Development Education Center (ARDEC South) in Fort Collins. The system was installed in May 2019 and is comprised of repetition plots of various treatments for scientific significance. The system includes three plots of open-field control plots, three plots of 72-cell bifacial solar panels, three plots of 72-cell opaque polycrystalline solar panels, and three plots of thin film 40% semi-transparent solar panels.

What Have We Learned?

The research and development team has learned that many crops respond very well to partial shade conditions without hindering growth. The partial shade from the panels has led to increased soil moisture and decreased ambient temperature, allowing the crops to avoid heat and drought stress that they may experience in full sun conditions. Fort Collins’ semi-arid climate and intense UV radiation along the Front Range can be a challenging place for certain crops to grow.

The team is continuing to model and research various panel types and layouts. Within the next two years, they hope to find the ideal ratio of transparency to power generation. Thin-film and semi-transparent solar technologies are expanding and progressing every year, leading to new potential solutions.

How Was Last Year’s Growing Season?

The team collected a lot of data in 2021, including measurements of temperature, Photosynthetically Active Radiation (PAR), light, and soil moisture throughout the growing season. They also collected harvest data on peppers, tomatoes, lettuce, and kale. Results indicate that all of these crops performed very well in partial shade conditions.

Learn more about Sandbox Solar’s Agrivoltaic Research & Development here: