FEATURE: Agrivoltaics: Combining Agriculture and Solar PV for a Sustainable Future

California is leading the charge in clean energy with its ambitious goals.  By 2030, the state aims to have 60 percent of its energy coming from renewable sources, and by 2045, it plans to achieve 100 percent renewable and zero-carbon energy.  In 2021, California made significant progress towards these goals, with over 37 percent of its retail electricity sales coming from renewable sources.

While solar power, wind power, and other renewable sources will play a crucial role, one challenge is the amount of land needed to produce renewable energy compared to fossil fuels.  However, there is a solution on the horizon: agrivoltaics.

Agrivoltaics combines the use of land for both agriculture and solar photovoltaic energy generation.  Rather than seeing agriculture and solar energy as competitors, agrivoltaics takes a complementary approach.  This innovative technique has the potential to generate energy on farmland while simultaneously reducing water usage, minimizing the impact on natural lands, and increasing crop yields.  Agrivoltaics could help California achieve its clean energy goals while supporting its agricultural industry.

In December of 2022, the Department of Energy awarded $8 million to six selected projects across the United States to study different aspects of agrivoltaics to understand better how the practice can become more widespread.  While none of those six projects were in California, the state legislature is considering SB 688 to support agrivoltaics research and interagency coordination.

In August of 2023, the California Council for Science and Technology held a webinar with a panel of experts who discussed the potential for development, challenges, and benefits of agrivoltaics in California.

So, what exactly is agrivoltaics?  It’s more than just solar panels located on a farm.  Jordan Macknick, Lead Energy-Water-Land Analyst with the National Renewable Energy Laboratory (NREL), said his agency’s definition includes agriculture and solar being directly integrated so that the solar panels are affecting the ground cover and the agricultural activities underneath and vice versa.

Majdi Abou Najm, Associate Professor at UC Davis, said agrivoltaics is a climate-smart method for maximizing the potential of limited resources.  “I see it as a key player in maintaining food security for the 10 billion people inhabiting this planet by 2050.  I see it as a key player in dealing with heat extremes, drought, salinity, and other challenges that significantly impact our food, water, and energy rating.  But also, at the far scale, I see agrivoltaics as the technology that can maximize our farmers and growers’ output from their lands.  So agrivoltaics can create the synergy between agriculture, energy, environment, and climate to optimize the most important resources at the farm, particularly the sun, water, and soil – all this to boost land efficiency.”

Microclimates and their effects on crops

Solar panels create microclimates that have a cooling effect during the day and a warming effect at night.  Solar panels also have the potential to reduce water use and protect crops from heat extremes, hail, or frost damage.  There are seasonal effects as well; the shade from solar panels can delay the germination of seeds, but solar panels can also extend the growing season.  And the vegetation underneath solar panels cools the PV panels and improves their performance.

Many agricultural activities are compatible with different solar technologies, arrangements, and configurations.  These include projects that integrate solar panels with crops, livestock grazing, and ecosystem services, such as sequestering carbon.  Solar-powered greenhouses are also a form of agrivoltaics.

The crops most suitable for agrivoltaics favor shade, such as tomatoes, peppers, basil, grapes, and berries.  Majdi Abou Najm experimented with shade and tomatoes and produced tomatoes using 10% less water.

Jordan Macknick has had success with growing lettuces and tender greens well into August.  “It’s really about finding a nice niche, so when things are out of season for traditional agriculture in that area, agri-tech opens up that door to provide that produce when no one else is able to grow it,” he said.

“Part of the sun can be more than what the crops need for photosynthesis, Majdi Abou Najm said.  “So, if we design agrivoltaic systems to take part of the solar light and provide the needed part of light for crops, that this is where we can provide the most optimum agrivoltaic system because we are making use of every single photon either for photosynthesis or for electricity.  This can reduce water use and extreme heat stress and provide water savings.”

California farmers remain hesitant

Declining water availability is motivating farmers to look at the options for using their land.  However, despite the potential of agrivoltaics, farmers have been hesitant to adopt agrivoltaics as they want to see how it will work in California, its impact on agricultural yield, and implementation challenges.

Understanding the financial impacts is important as agrivoltaics projects require a long-term commitment.  Maintenance costs need to be considered, as dust from agricultural operations can settle on the panels, affecting their productivity, and livestock, such as sheep, can gnaw on wires, causing damage.  Fluctuating energy prices and commodity prices add to the uncertainty.

Landowners also have concerns over preserving the farmland for future generations.  Ranjitha Shivaram, Energy Systems Researcher and Ph.D. Candidate at Stanford, noted a fundamental difference between farmers and ranchers.  “A lot of the ranchers we spoke to were very concerned about how it would look if the rolling hills around were covered with solar panels,” she said.  “They take a lot of pride in how their land looks and that’s a lifestyle-related value that’s a major consideration for many of them.”

“It needs to work for the farmer, it needs to work for the solar company, and it needs to make financial sense,” said Jordan Macknick.  “It’s complex for a farmer to make it work, and it’s complex for a solar developer to make it work.  And now we’re asking both teams to collaborate and come up with a design that works for both folks … sometimes the things that a farmer wants to do are going to eat into the economics of the solar developer.  And, some of the things that solar developers might want to do might eat into compatibility with farm equipment operations and the yield for the farmer themselves.”

Plugging into the grid

An important consideration is scale – both the scale of agricultural operations and loads, as well as the scale of the land and the solar project.  “Depending on what scale you’re at, you might qualify for a net metering program, or you might get a PPA, which can have very different impacts on the price you’re getting for the electricity you’re generating,” said Jordan Macknick.  “For every electron you’re producing, you could get a wholesale rate or a retail rate, which can be vastly different.  So this is where that scale question really comes into play.”

Access to electrical transmission and distribution infrastructure is necessary if the electricity generated is to be sold to the grid, and a project must generate enough electricity to make it economically viable.  However, many farmers only want to consider a small portion, 5-10% of their land, for solar development.  So, pulling together smaller chunks of neighboring parcels could be a way to have enough land to connect to energy infrastructure, panelists said.

In cases where connection to the grid is not possible, farmers can use solar power to reduce their energy costs from farm operations, such as drip irrigation and processing of crops.  Energy storage can be great for energy reliability, but it can have a substantial economic impact, making the project not viable financially in most cases.

“Many of the growers I talked to tell me their $1000 to $2,000 a month energy bill is one of their main concerns,” said Majdi Abou Najm.  “If we can offset that from creating green energy through solar panels while also creating shade that saves water, those are the additional benefits that growers can consider.”