Tag Archive for: solar farming

New Reports Highlight Best Practices of Combining Solar Energy and Agriculture

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.

Case Study: Jack’s Solar Garden

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. 

Massachusetts Solar Pollinator Meadow Flourishes 

“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  

AgriSolar News Roundup: Cows in Agrisolar, Agrisolar in Nebraska, Small Farms Using Kunekune Pigs 

Michigan Agrisolar Farm Includes Cattle 

“Since farms use a significant amount of energy, generating electricity directly on the farm is appealing for those seeking to reduce expenses. Also, farming-friendly solar is possible where several farms have married on-farm solar with rotational grazing of livestock. While sheep have been the predominant livestock used in solar pastures, new approaches show the possibility of harvesting the sun and providing pasture for grass-fed cattle on the same site. 

Farming-friendly solar is made possible by engineering a system where the panels are raised upwards of eight feet off the ground, allowing cattle to move beneath. On hot summer days the cattle seek relief from the sun in the shade from the panels. Similarly structured to a carport, the elevated solar structure is designed to withstand rugged outdoor applications with a properly supported foundation to manage the higher wind pressure.” – Michigan Farm News 

Nebraska Pork Producers Benefit from Agrisolar  

“A Northeast Nebraska pork producer is using renewable energy to promote sustainable agriculture and offset energy consumption on his farm. 

Jason Kvols tells Brownfield he installed 300 solar panels on the top of his hog barns two years ago and an app tracks the impact on the environment. ‘It coverts it to pounds of carbon dioxide saved through this solar system.  Over the two years, it’s up to 432,000 pounds of CO2 that my system has saved in production from two years.’ 

He says he received a 26-percent tax credit on the project, and it has a 7- to-8-year payoff period.” – Brownfield 

Kunekune Pigs Found to be Ideal for Small Farms 

“Kunekune (pronounced “cooney cooney”) pigs are a good option for small farms and homesteads. The animals’ gentle nature, manageable size, and low input requirements beyond minimal rations and standard veterinary care like vaccinations and de-worming, make them a smart pick for those looking for an entry point into livestock production.” – Eco Farming Daily 

You can find a free Kunekune Pig Guide here, provided by Eco Farming Daily. 

Effects of Shading Nets on Reactive Oxygen Species Accumulation, Photosynthetic Changes, and Associated Physiochemical Attributes in Promoting Cold-Induced Damage in Camellia sinensis (L.) Kuntze

Climate change and extreme weather affect tea growing. A competitive tea market needs quick, short-term solutions. This study evaluates the effects of various shade nets under mild and extreme cold stress on tea leaf physiology, photosynthetic alterations, antioxidant activities, and physiochemical characteristics. Tea plants were treated with SD0 (0% non-shading), SD1 (30% shading), SD2 (60% shading), and SD3 (75% shading). The 30%, 60%, and 75% shade nets shielded tea leaves from cold damage and reduced leaf injury during mild and extreme cold conditions compared with SD0% non-shading. Shading regulates photochemical capacity and efficiency and optimizes chlorophyll a and b, chlorophyll, and carotenoid contents. Moreover, carbon and nitrogen increased during mild cold and decreased in extreme cold conditions. Shading promoted antioxidant activity and physiochemical attributes. In fact, under 60% of shade, superoxide dismutase, peroxidase, catalase, and omega-3 alpha-linolenic acid were improved compared with SD0% non-shading during both mild and extreme cold conditions. From these findings, we hypothesized that the effect of different shades played an important role in the protection of tea leaves and alleviated the defense mechanism for “Zhong Cha 102” during exposure to a cold environment.

horticulturae-08-00637Download

AgriSolar News Roundup: GivePower Aquavoltaics, Solar Decommissioning Resource Guide, Chinese Aquavoltaics Deployment, Solar Irrigation in Nebraska

GivePower Desalinates Water Overseas Using Aquavoltaics 

“Austin, Texas-based GivePower started by installing solar panels for schools, community centers or other projects in communities in need. But GivePower founder Hayes Bernard realized that people, especially women and girls, would not attend school if they had to walk 8 miles to get water every day. That’s when the idea to include water pumps and desalination came to mind.  

GivePower has seven operational desalination sites in countries like Haiti, Kenya, and Colombia. Four additional solar water farms are expected to become operational by the end of this year. GivePower has different sized desalination sites and setups. The largest one, the Solar Water Farm Max, produces up to 18,500 gallons of water daily — enough to support 35,000 people. It has a solar structure that acts like a roof over the water tanks and the twenty-foot equivalent unit shipping containers that house the desalination technology.” – American Shipper 

Resource Guide for Decommissioning Solar Energy Systems 

A new resource guide on decommissioning solar energy systems, written by AgriSolar Clearinghouse partner Heidi Kolbeck-Urlacher, offers resources for understanding solar project end-of-lifecycle management and recommendations for local governments to consider when drafting decommissioning ordinances. The report is now available through the Center for Rural Affairs here.  

“Solar projects are often located in rural areas and can provide numerous benefits to nearby communities, including lease payments to landowners, tax revenue to fund infrastructure and services, and the creation of both permanent and temporary jobs. County officials are typically responsible for enacting siting or zoning standards to help ensure solar development is supported by local residents. This can include planning for the eventual decommissioning of energy projects that have reached the end of their life cycles.” – Center for Rural Affairs 

The guide includes examples of decommissioning costs, extending performance periods of solar systems, recycling and disposal of solar panels, sample task lists associated with decommissioning solar systems, and recommendations for plans that define obligations of developers during the decommissioning process.  

Chinese Fishery Deploys 70MW Solar Plant 

“Farms where fish and algae thrive under solar panels might have secured their place in a future powered by renewable energy. Concord New Energy, a Chinese company that specializes in wind and solar power project development and operation, has installed a 70 MW solar plant atop a fishpond in an industrial park in Cangzhou, China’s Hebei region. The hybrid system integrates solar power generation with fishery in a unique way that not only saves land but also produces clean energy. This hybrid system is straightforward: a solar array is installed above the fish pond’s water surface, and the water area beneath the solar array is used for fish and shrimp farming. 

The fishery-solar hybrid system is a type of floating solar farm that has grown in popularity over the years as solar power has evolved to meet the needs of our increasingly climactic times. For example, the United States has just begun construction of the country’s biggest floating solar farm in New Jersey.” – Interesting Engineering 

Valley Irrigation Develops Solar Irrigation Site in Nebraska 

Valley Irrigation has announced the completion of its first North American agrisolar installation in Nebraska through its partnership with Farmers National Company. 

“The installation is located near Davenport, Nebraska, and will provide solar power to a Valley center pivot by offsetting energy consumption used to irrigate the field. Farmers National Company’s landowner client invested in Tier 1 solar panels, which are the highest-quality panels and are also used on major utility-sized installations. They are built to withstand the often-harsh conditions of Nebraska weather, including strong winds and hail.” – Valmont 

“Matt Gunderson is with Farmers National Company and says it helps producers become more sustainable and increase return on investment. “We create some on farm generation not only to power a farm, but how do we tie it back into the grid system to support the electricity needs that are out there? And, along the way with it, sell that electricity back for some excess needs and create some investment opportunities and income generation for producers.” – Brownfield 

Manzo Elementary School Solar Garden

Manzo Elementary School, located in Tucson, Arizona, is a Flagship School for the University of Arizona Community and School Garden Program and a fellow agrivoltaic site to Biosphere2. The school has had an award-winning ecology program for over a decade, which includes a garden and hen house cared for by the students as a way of learning. In 2015, the school erected a 193-kW (600 PV panels) solar PV array as a part of the Tucson Unified School District Solar Program. This system produces approximately 490-500 MWh per year.

The Manzo Solar Array

Working with Greg Barron-Gafford from the University of Arizona, the school installed a small garden under the panels and an unshaded control garden to the west of the panels. Plants range from potatoes to tomatoes, basil, beans, and squash. The research on this site is similar to Biophere2 in that they study phenology, soil health, water consumption, and greenhouse gas consumption. Graduate students typically study both sites for a comprehensive thesis.

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

What makes this site unique is the participation of the Manzo’s students, who take part in the studies by assisting with planting, caring, watering, and harvesting the fruits and vegetables. Once harvested, the food goes to the Food Literacy Program, located in the Manzo cafeteria, so the students can then learn how to wash, prep, and cook the food they grew. Research at the school show similar results to Biosphere 2. A key finding in this research proved that solar garden plants need less watering. This is important for farming in Arizona, where temperatures can reach well over 100oF and water sources are slowly being depleted. Research also found that seeding can take place earlier due to the cooler temperatures under the panels, allowing for a possible second planting and increased production. The solar garden plants can flourish in extreme weather because they are shaded during the hottest times of the day.

Overall, Greg Barron-Gafford and his graduate students are proving that solar and farming can co-exist to benefit landowners and farmers alike. The research being conducted at both Manzo School and Biosphere2 will have positive impacts on the co-existence of solar production and desert farming.  

Under the panels at Manzo Solar Garden
Berries under the panels at Manzo Solar Garden

Massachusetts Farm Partners with BlueWave in Dual-Use Solar

The Knowlton Farm, a Massachusetts agrisolar operation, has recently partnered with BlueWave Solar to expand agrisolar operations on the farm in Grafton, according to an article by The New York Times.  

Owner Paul Knowlton stated that the farm typically produces a variety of vegetables, dairy products, and hay, but also produces solar energy. He said that solar was already part of the farming operations, providing electricity for both his barn and home, but through this partnership with BlueWave, the farm will include a parcel of land where solar panels will share space with crops, known as dual-use solar, according to the report. 

The dual-use solar operation includes adjusting the heights of solar panels to allow farm operations, including workers, equipment, and grazing animals, to operate underneath them. Spacing and angles of the solar panels are adjusted to benefit crops growing below them—shielding them from the elements, including intense heat. Some of the panels will have cattle grazing beneath them while others will grow butternut squash and lettuce. 

The AgriSolar Clearinghouse will be touring the Knowlton Farm on August 10, 2022, as part of the Follow the Sun Tour. The tour is a series of hands-on field trips to see firsthand the benefits of co-locating sustainable agriculture and solar energy. Other locations on the tour include the Massachusetts Amherst South Deerfield research site and the Million Little Sunbeams family farm. 

Biosphere 2 Agrivoltaic Learning Lab

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

Tasting the Fruits and Vegetables Grown Under Solar Panels

By: Mariah Rogers, Graduate Student, University of Arizona

Do plants taste different under solar panels? Do they taste better? At the Biosphere 2 Agrivoltaics Learning Lab, we studied just that.

Why Should We Use Agrivoltaics?

Agrivoltaics—the production of agriculture and solar photovoltaic energy on the same parcel of land—is gaining attention as farmers are facing new struggles amid the climate crisis. With agrivoltaics, farmers can reduce water consumption, produce renewable energy, and continue to cultivate their land. However, there is skepticism toward growing crops under solar panels, as farmers may have to change the types of plants that are more shade tolerant.

The Biosphere 2 Agrivoltaics Learning Lab

At the Biosphere 2 Agrivoltaics Learning Lab (B2AVSLL), we study the microclimate—that localized environment under the solar panels— and how plant adaptations occur in the shade of the agrivoltaic system. Some of the adaptations that plants make in the agrivoltaic microclimates include differences in yield, changes to plant morphology (leaf size, fruit shape and color), and alterations in metabolites. These adaptations may cause differences in how people perceive these crops. To study these differences, we grow a slew of different crops underneath solar panels.

We grow tomatoes, basil, potatoes, beans, squash, and lavender, just to name a few. While some of the plants grown at B2AVSLL are heat tolerant, crops grown in this region of the U.S. still require a lot of water. With agrivoltaics, we can reduce water consumption and still have a good yield. So, it is in our best interest to figure out if they would be successful both for the environment and in the market.

The Study Goals

To understand how these crops would do in the market, we conducted a consumer sensory study at the University of Arizona. The three goals of the study were to: (1) to understand if people perceived a difference between agrivoltaic-grown crops vs. crops grown in full sunlight (control); (2) determine if people preferred agrivoltaic-grown crops compared to control; and (3) discover if people were willing to pay more for crops grown in agrivoltaic conditions.

A total of 105 people participated in the study. Panelists were subjected to different conditions and samples, based on the site and the day they were tasting samples. Tomato and basil, potato and bean, and potato and squash were tasted by panelists.

Does Agrivoltaics Change the Flavor of Plants?

To understand if there was a difference between agrivoltaic- and control-grown samples, we used a triangle test where participants were given three samples with a random three-digit code; two of the samples were the same and one was different. We then asked the participants to pick which sample was the “odd one out.”

So, did agrivoltaics change the flavor of the crops? Yes and no. Tomato, bean, and squash samples (all fruits) were perceived as different by tasters. Basil and potato samples were not perceived as significantly different by tasters.

Does Agrivoltaics Make Plants Taste Better?

To understand if there was a preference between samples from the two growth conditions, we then conducted a paired preference test. We gave tasters two samples with random three-digit codes and asked if they preferred one sample more than another, or if they preferred neither sample.

Unsurprisingly, the results were mixed. People significantly preferred beans grown in the control setting over those grown in agrivoltaics. In addition, agrivoltaic-grown basil, potato, and squash samples were preferred by tasters.

Are People Willing to Pay More for Agrivoltaic-grown Produce?

After the triangle and preference tests, we asked participants if they would be willing to pay more or less for their favorite samples. Overall, we found that participants were willing to pay the same or more for all samples after they knew that their favorite samples were grown in agrivoltaic systems.

What Does This Mean for Farmers and Investors?

Because consumers can’t tell a significant difference in vegetable samples, and they preferred basil, potato, and squash, it may be in farmers’ best interest to grow these crops, especially in the desert. By marketing the produce as grown under solar arrays, and educating consumers about agrivoltaics, farmers may be able to sell their produce for slightly more at farmers markets.

What Does This Mean for You as a Consumers?

Buying for foods that are grown using agrivoltaics means supporting solar energy generation through purchasing fruits or vegetables. If you already go to the farmers market to buy fruits and vegetables, you may want to consider buying agrivoltaic-grown produce. If you want something that tastes like what you already buy from the farmers market, then you may want to buy vegetables. If you are looking for a different tasting product, you may want to buy fruits grown under agrivoltaics. You can be the judge whether you prefer one growth condition over another.