Tag Archive for: solar-suitable crops

Agrisolar as Drought Protection  

By Asaf Maman and Avi Elkayam, Trigo Solar 

Declining precipitation levels and the associated reduction in arable land can negatively impact rural communities and pose a threat to food security. While utility-scale solar projects reduce greenhouse gas emissions, they can also encroach on arable lands and reduce the yield of rainfed crops. Wheat, barley, soy, corn, and other grains are cultivated in rainfed fields that are vital to food security. As precipitation levels decline and desertification spreads, arable land and farms that produce these crops are in peril.   

As solar energy is employed in the conversion from fossil fuels to renewable energy, hundreds of thousands of square miles of land will include solar development. According to the National Renewable Energy Laboratory, there will be roughly 22,000 square miles of solar in the U.S. by 2035i. It is important to understand that the actual land for solar development must be adjacent to grid or to power demand centers. The growing competition between farming, suburban development, and solar development highlights the potential for agrivoltaics.  

Agri-PV is a solution to this issue. It can significantly improve the cultivation of staple foods that substantially affect global food security by cracking the code and untying the water-land knot. By increasing the amount of water available for rainfed crops, we can increase the amount of arable land and avail a portion of it for sustainable solar development. 

In a series of field-controlled winter wheat experiments, Trigo has discovered an almost linear correlation between the amount of water supplied to cultivated area and the quantity of stem biomass and nutritional value. Based on these findings, Trigo designed an east-west solar array formation and solar table structure to both collect and regulate rainwater for redistribution into a cultivated row below. By increasing the rain capture area from both structures, enclosing, and effectively directing the rain, we managed to control the amount of water and increase it, countering the effects of declining precipitation over years.  

North-south solar array over winter wheat. Photo: Trigo Solar 

Design schematic. Source: Trigo Solar 

This design is focused on economic and efficient deployment of solar arrays that improve rain collection and redistribute water to boost crops growth, counter drought effects, and revive agricultural operations.  

Rainwater catchment design schedmatic. Source: Trigo Solar 

Benefits to this design include:  

  1. Maintaining the same yields from smaller cultivated surface area requires more limited farming operations and lower expenses, which can increase farm profitability. 
  1. Capturing more water and channeling it smartly reduces the risk of drought and the associated annual volatility and provides the farm with a drought shield. 
  1. Increased ground wetness, root growth, and wind shield from the solar rows reduces the erosion and carry away of the upper soil layer, which create irreversible damage to farms. 
  1. Preserved land under the Trigo structure can be used for future land reserve and land rotation. 
  1. The steady income from solar power generation can support farm economics and mitigate farming financial risks. 
  1. The availability of cheap, local, green power can further support many of the farm operations expected to undergo electrification in the coming decade. 
  1. The existence of a water-distribution and cheap-power system changes the economics of farming, potentially allowing the cultivation of second seasonal crop during the dry season.  

These benefits have the potential to create more win-win opportunities for effective cooperation between the agricultural and sustainable energy sectors. 

Trigo will continue its experiments to validate the benefits for major U.S. staple crops at U.S. farms to share the knowledge and promote sustainable mass Agri-PV development.  

AgriSolar News Roundup: Win for America’s Farmers, 5 Signs of Agrisolar Revolution, Agrisolar Pumps in India, Harvesting Light in Agrisolar, Massachusetts Solar Incentives 

Win for America’s Farmers: Harvesting Solar Energy 

“America’s solar industry has boomed in recent years, and is slated for a big boost from the Democrats’ recently passed climate bill. Yet solar still only accounts for about 3 percent of electricity flowing into America’s grid—less than one-seventh the share from coal. If we want to phase out fossil fuels and accommodate an electric vehicle revolution, the sun’s contribution has to rise dramatically—and fast. But where to put all the panles?

The best places for solar installations, according to a 2019 study from the University of Utah and Oregon State, tend to be the areas where we already grow our food. That’s because, just like sun-loving tomato plants that fare poorly when the mercury creeps north of 85 °F, photovoltaic (PV) panels lose their efficiency at higher temperatures. But that doesn’t mean we have to starve ourselves to keep lights on and cars humming. By elevating solar panels far enough above the ground so people, plants, and animals can operate underneath, we can “essentially harvest the sun twice,” says University of Arizona researcher Greg Barron-Gafford. Enough sunlight to grow crops gets past the panels, which also act as a shield against extreme heat, drought, and storms.” – Mother Jones  

5 Signs the US Agrisolar Revolution has Begun  

“An upswell of opposition to large-scale solar power plants on farms took shape in the U.S. last spring, partly fueled by conspiracy theories about climate change. Nevertheless, farmland is attractive to solar developers. Now they have a new support system on their side, in the form of agrivoltaics.” – Triplepundit.com  

Solar Energy Corporation of India Issues Tender to Install Agrisolar Pumps 

“New Delhi: The Solar Energy Corporation of India (SECI) on Monday issued a tender for setting up agricultural solar pumps in selected states pan-India under component-B of the PM-KUSUM scheme of the renewable energy ministry.  

‘Individual farmers will be supported to install standalone solar agriculture pumps of capacity up to 7.5 HP for replacement of existing diesel agriculture pumps and irrigation systems in off-grid areas, where grid supply is not available. Installation of new pumps will be permitted under this scheme except in dark zone areas,’ said the SECI tender document.” – Energyworld.com 

UC Davis Study Shows Harvesting Various Light Spectra Benefits Agrisolar  

“Scientists from the University of California, Davis, are investigating how to better harvest the sun — and its optimal light spectrum — to make agrivoltaic systems more efficient in arid agricultural regions like California. 

Their study, published in Earth’s Future, a journal of the American Geophysical Union, found that the red part of the light spectrum is more efficient for growing plants, while the blue part of the spectrum is better used for solar production.” UCDavis.com 

Massachusetts Sees Increase in Agrisolar Incentives 

“A Massachusetts incentive program for projects that blend solar energy and agricultural production shows signs of finally gaining momentum after a slow rollout that has at times frustrated solar developers and farmers alike. 

In 2018, Massachusetts became the first state to offer financial incentives for “dual-use” or “agrivoltaic” solar projects built above active agricultural land. Since the launch, however, just three projects have gotten up and running. Another eight have qualified for the incentive but not yet been built.” – Energynews.com  

Price for Covering Cropland with an Agrivoltaic System: PV Panels Replacing Shading Nets in Chilean Blueberry Cultivation

Researchers analyzed and compared the costs for an agrivoltaic system with the cost of plastic covers for blueberry crops in Chile. They also introduce a metric to calculate the price for covering cropland with an agrivoltaic system.

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Microclimate Under Agrivoltaic Systems: Is Crop Growth Rate Affected in Partial Shade of Solar Panels?

Researchers in this study monitored soil and air temperature, humidity, wind speed, and incident radiations at a full sun site, as well as at two agrivoltaic systems with different densities of photovoltaic panels. They recorded the findings during three seasons (winter, spring, and summer) with both short cycle crops (lettuce and cucumber) and a long cycle crop (durum wheat). The researchers concluded that little adaptations in cropping practices should be required to switch from an open cropping to an agrivoltaic cropping system and attention should mostly be focused on mitigating light reduction and on selection of plants with a maximal radiation use efficiency in these conditions of fluctuating shade.

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The Impacts of Agrivoltaics on Crop Production

This PhD dissertation addresses four primary questions: 1.) To what extent is plant-available radiation reduced by solar panels of a photovoltaic system? 2.) How does this effect parameters of aerial and soil climate? 3.) How do the cultivated crops respond to the altered cropping conditions with regard to plant growth and development? 4.) What consequences does this have regarding the yields and the chemical composition of the investigated crop-species? A field experiment in which grass clover, potatoes, celery, and winter wheat were planted under a photovoltaic facility in Southwest Germany was conducted to answer these questions.

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AgriSolar Podcast Ep. 1: Growing Crops Among the Solar Panels in Colorado

The AgriSolar Clearinghouse Podcast officially kicks off with a conversation between Meg Caley, Executive Director and co-founder of the Colorado nonprofit Sprout City Farms and NCAT Energy Director Stacie Peterson. They discuss the many additive benefits of agrisolar, the challenges of farming in an obstacle course, and the importance of community. AgriSolar podcast episodes will be available on Voices from the Field, NCAT’s ATTRA sustainable agriculture podcast series.

Sprout City Farms began in 2010 with a vision of increasing food access and community resiliency through farming underutilized urban land. Among its partnerships, Sprout City Farms works with Jack’s Solar Garden in Longmont, Colorado, growing crops in the spaces between solar panels at the site, which is the largest agrivoltaic research facility of its kind in the United States.

You can read more about Sprout City Farms, Jack’s Solar Garden, and the Colorado Agrivoltaic Learning Center at these websites: 

Sprout City Farms 

Jack’s Solar Garden 

Colorado Agrivoltaic Learning Center 

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Yield Response and Physiological Adaptation of Green Beans to Photovoltaic Greenhouses

This study evaluates green bean cultivation inside greenhouses with photovoltaic (PV) panels on the roof. Researchers found that the beans adapted to the change in shading by relocating more resources to the stems and leaves. As a result, average yield decreased compared to that of a conventional greenhouse. However, an economic trade-off between energy and crop yield can be achieved with a panel coverage of 10%. The research also provides an experimental framework that could be replicated and used as a decision support tool to identify other crops suitable for solar greenhouse cultivation.

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AgriSolar News Roundup: French Farmers Going Agrisolar, Agrisolar Event in Kentucky, EarthTalks Agrisolar Series

Farmers in France are Beginning to Combine Solar Panels and Crops 

“In the Haute-Saône region, in the northeastern part of the country, an experiment is being conducted by solar-energy company TSE. It is hoping to find out whether solar energy can be generated without hindering large-scale cereal crops. Previous attempts to experiment with agrivoltaics have been through smaller-scale projects. But, keen to see if it can thrive on an industrial level, 5,500 solar panels are being spread over this farm in the commune town of Amance by TSE.”  – Euronews 

Solar Grazing Event Helps Kentucky Students Learn about Agrisolar 

“The event was made possible through a partnership between the Kentucky Sheep and Goat Development Office, LG&E/KU, University of Kentucky, Ohio State University, and solar development company Lightsource bp. Students learned about solar technology, seed mix establishment and meeting nutritional needs in solar grazing. Additionally, the release said students were able to tour the LG&E/KU E.W. Brown Generating Station’s solar array in Mercer County.” – The News Enterprise 

Cornell Researcher Hosts EarthTalks Agrisolar Series 

“Niko Kochendoerfer, a postdoctoral fellow in animal sciences at Cornell University, will deliver the talk ‘Effect of sheep stocking rate on ecosystem parameters in ground-mounted solar arrays’ at 4 p.m. on Monday, Nov. 14. The talk, which is free and open to the public, takes place in 112 Walker Building on the University Park campus and via Zoom.”  – PSU 

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Current Status of Agrivoltaic Systems and Their Benefits to Energy, Food, Environment, Economy, and Society

This article offers practical advice for agrivoltaic systems on how to implement an agricultural area under ground-mounted photovoltaic-power systems without agricultural “pre-plans.” These systems are useful for policy making and optimizing land use efficiency in terms of energy production, food supply, environmental impact, local economy, and sustainable societies.

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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.