Tag Archive for: solar farming

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.

Financing and Incentive Options for Solar

By: Andrew Valainis

Director, Montana Renewable Energy Association (MREA)

According to the Solar Energy Industries Association, the cost to install solar has dropped more than 60% over the last decade alone, with the average residential system costing half of what it did in 2010.[1] Still, solar photovoltaic systems are a large investment, and the up-front cost can be challenging for many Americans. In this blog post, I will explore some of the financing and financial incentive options available to help pay for these systems. I use Montana’s available options as examples, though financing and incentive programs will vary state to state.

One of the most popular and most important incentives in the U.S. is the Solar Investment Tax Credit (ITC). The ITC is a federal income tax credit that you can claim against the cost of the installation. This credit applies to the total cost of the installation, including labor. If you decide to install a storage system at the same time as the solar system, then you can include that cost as well. There is no upper dollar limit on how much the credit is worth. The ITC was originally set at 30% but stepped down to 26% in 2020 and will continue to step down over the next few years. In 2020, the phase-out schedule was extended for two years as part of the spending bill that Congress negotiated. The ITC will remain at 26% until 2023, when it will step down to 22% for all customers. In 2024, it will expire for individuals, while stepping down permanently to 10% for businesses.

Federal ITC Step Down 2020 Extension.

Another great option is the U.S. Department of Agriculture’s “Rural Energy for American Program” (REAP). The REAP program provides grants – not loans – to qualifying agricultural and small businesses for up to 25% of the cost of a renewable energy project, up to $500,000. Energy efficiency grants and loan guarantees are also available through the program. This is an excellent option for agricultural producers. USDA has local offices all around the country, and I highly recommend calling them to ask about the program and how you can benefit.

In 2022, Congress passed the Infrastructure Investment and Jobs Act (IIJA), which provides a large amount of funding for the installation of renewable energy technologies. Details are still coming out about several of the different funding opportunities, which may apply to businesses or individuals. These are worth monitoring for further information. You can learn more here.

Some states offer state-level programs specifically supporting the development of solar and other renewable energy technologies. In Montana, we have the Alternative Energy Revolving Loan Program (AERLP). This program was established by the Montana Legislature in 2001 and provides zero-down, low-interest loans of up to $40,000 to individuals, small businesses, nonprofit organizations, and government entities in order to increase investments in alternative energy systems and energy conservation measures in Montana. The program, managed by the Montana Department of Environmental Quality’s Energy Office, has financed more than 500 renewable energy installations across the state since its first loan in 2003. States also often offer tax incentives or rebates for renewable energy installations, which are great options to help lower the up-front cost of the installation. Reach out to your state energy office or solar advocacy group to ask what options your state offers.

Property Assessed Clean Energy (PACE) programs are becoming more popular across the country. PACE programs offer the opportunity to finance the up-front cost of an installation and then pay back that cost as an assessment on the property taxes of the building or location where the system was installed. One of the greatest benefits is that the cost of the system is tied to the location, making for a simpler process if there is a change in ownership. The nuances of these programs are important and will vary from state to state. For example, the recently adopted PACE program in Montana is only available to commercial entities.

Your utility may offer discounts, rebates, or other incentives that can help with the cost of renewable energy and/or energy efficiency technologies. In Montana, we have the Universal Systems Benefits (USB) program. Our largest investor-owned utility, NorthWestern Energy, administers this state-authorized incentive program through its “E+ Renewable Energy Program” to qualifying non-profit organizations, government agencies, and schools in NorthWestern Energy’s Montana service territory. Projects receiving these funds often provide civic value, including education and visible representation of renewable energy technologies to a broad audience. The Montana USB program provides grants, but other utility territories may offer programs with discounts or rebates on certain energy efficiency products. Reach out to your energy provider to ask what incentives it offers. 

Private financial institutions are beginning to offer their own renewable-energy focused products. For example, Clearwater Credit Union (based in Missoula, MT) offers two home energy loans: an unsecured, easy-access Home Solar Loan; and a Home Energy Efficiency Loan. Because it is a private institution (and not a state agency), the credit union can usually offer a decision in minutes. These options can be particularly attractive for businesses or households that already have an account with that institution.

Third-party financing is another option to consider. In this scenario, a private, third-party financer will develop a solar project on leased or purchased land or roof space. The financer provides the capital and, in doing so, is often able to take advantage of tax breaks that can lower the overall project cost. They enter into a contract with the system host (i.e., the building or land owner) who then benefits from the project by receiving the energy produced on-site. The host may pay the financer a regular payment (fixed or otherwise) related to the value of the energy delivered. At the end of the contract term, the host may also have an option to purchase the system from the financer. The crux is finding a third-party financer you are comfortable working with. These types of contracts can be technical, and the nuances are very important. If you are interested in this model, I recommend working with a legal expert to make sure you understand the terms and conditions of any agreement that you sign. Missoula County recently worked on the first third-party financed system in Montana. MREA hosted a webinar about the experience, and about third-party financing in general. A link to the recording is provided below.

A closing note on tax incentives (generally): Be sure to consult with a tax professional to ensure that these options are available to you. Unless the tax credit is specifically noted as refundable, you must have a sufficient tax liability to claim the value of the credit. For example, the Federal ITC is not currently refundable (though SEIA and other solar advocates have lobbied Congress to make it so).

As you can see, there are varied options available to help with the cost of a solar installation. However, the nuances are important and can drive the cost and savings that you will eventually realize. As you explore these different options, be sure to reach out to local solar advocates and legal and tax experts in your area with any clarifying questions.

Resources:

Federal ITC (for businesses)

Federal ITC (for residences)

USDA REAP Program

IIJA funding opportunities

MREA webinar on Third-Party Financing

Montana-specific Programs and Examples:

MREA website on financing and incentives

Alternative Energy Revolving Loan Program

Clearwater Credit Union energy loans

Northwestern Energy E+ Renewable Incentives

[1] Solar Energy Industries Association. (2022). “Solar Industry Research Data.” https://www.seia.org/solar-industry-research-data

Photosynthetically Active Radiation Decomposition Models for Agrivoltaic Systems Applications

Decomposition models of solar irradiance estimate the magnitude of diffuse horizontal irradiance from global horizontal irradiance. These two radiation components are well-known to be essential for the prediction of solar photovoltaic systems performance. In open-field agrivoltaic systems, that is the dual use of land for both agricultural activities and solar power conversion, cultivated crops receive an unequal amount of direct, diffuse and reflected photosynthetically active radiation (PAR) depending on the area they are growing due to the non-homogenously shadings caused by the solar panels installed (above the crops or vertically mounted). It is known that PAR is more efficient for canopy photosynthesis under conditions of diffuse PAR than direct PAR per unit of total PAR. For this reason, it is fundamental to estimate the diffuse PAR component in agrivoltaic systems studies to properly predict the crop yield.

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Comprehensive Solar Thermal Integration for Industrial Processes

This report shows industrial processes for comprehensive solar integration. The paper discusses solar thermal energy-integration methods, cost estimations of system components and solar fractions. Multiple case study examples relevant to the dairy and biothermal industry are presented. Each case study includes three scenarios, and the results of each of those are discussed here.

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Development of a Solar-Powered Submersible Pump
System Without the Use of Batteries in Agriculture

The purpose of this study was to describe the development of a solar-powered submersible pump system without the use of batteries in agriculture. The submersible pump system used a solar drive to run it. The implementation uses a combination of solar trackers, water storage tanks, power converters, and stabilizers. The results of the study explained that solar trackers increased the efficiency of solar units that track the sun throughout the day and convert solar energy into DC electrical power.

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Design and Analysis of a Tracking and Backtracking Strategy for PV plants with Horizontal Trackers After Their Conversion to Agrivoltaic Plants

This study discusses the analytics of tracking and backtracking for PV plants with various trackers after being converter to agrisolar plants or operations. Some of the details included in this report are: astronomical considerations, hedgerow crop height, tracking axis’s with and without crops, daily incidental radiation and solar declination, among other topics. These results could be used for implementing new strategies in future agrisolar operations.

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Physical analysis of the environmental impacts of fishery complementary photovoltaic power plant

This article discusses the mechanism of local micro-climate changes caused by fishery complementary photovoltaic (FPV) power plants to illustrate the impact of FPV power plants in a lake on the environment. It includes details about comprehensive albedo decreases relative to free water surface, water energy change and air vapor pressure deficits. The article also reveals that the FPV panels had a heating effect on the ambient environment, and that the range of this effect was related to water depth.

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A Pictorial Guide to Hedgerow Plants for Beneficial Insects

This publication provides a pictorial guide to several of the most beneficial hedgerow plant species used in farmscaping for native pollinators and insect predators and parasites in California.

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Prairie Strips Help Honey Bees and Wild Pollinators

This is a summary of research that tested the efficacy of prairie strip practice to improve honey beekeeping while maintaining a community of wild pollinators compared to farms without prairie strips.

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