Agrivoltaics: Where Solar Energy Meets Agriculture

Agrivoltaics is the use of solar panels in agriculture to produce both food and electricity. Around the world, the practice has several names: agrisolar, agrophotovoltaics, solar sharing, and PV agriculture.

Many experts believe agrivoltaics can minimize barriers to food security and the transition to clean energy. While the practice is still in its infancy, it is expected to grow as solar continues to boom throughout the next few decades.

How Agrivoltaics Works

Agrivoltaics involves mounting ground-mounted solar panels at a greater height than in usual solar arrays, leaving the soil underneath for agricultural production.

In the United States, 90% of projected solar growth by 2050 will happen in rural areas, according to the U.S. Department of Energy (DOE). Using rural land wisely through practices like agrivoltaics is key to solar development. It can reduce its impact on farming communities and rural wildlife while increasing solar energy's acceptance with the wider public.

The panels provide off-grid electricity to the farm and/or grid-tied electricity to the local community. The food produced under the panels can raise crops for the market or provide fodder and shade for grazing animals. Through net metering programs or through leasing their land to solar developers, farmers gain an economic benefit both from the crops and the energy they produce.

Benefits of Agrivoltaics

Using land for multiple purposes has multiple benefits. Adding those benefits up, one review of agrivoltaic practices found that land productivity increased by 70%.

Reduced Water Loss, Higher Yields

In providing shade, solar panels reduce evaporation of moisture from the soil below—in one study, by as much as 40% less moisture lost. The shade provided by solar panels can be used for water storage, and the water used for cleaning solar panels can then be recycled for crop irrigation. Reciprocally, the vegetation underneath the panels reduces heat stress and increases the panels' energy efficiency.

Livestock and crops under the panels also require less water. One study found that as temperatures rose in late spring, lambs browsing under solar panels required nearly a liter less water per day than lambs grazing in open fields. The study also found that even if solar pastures produced 38% less herbage, the loss was offset by its higher nutritional content, leading to similar lamb production as in open fields. With less water loss, even some shade-intolerant crops like corn showed increased yields.

Support for Farmers

Worldwide, farmland faces many threats: soil erosion, sea level rise, desertification, and, in the United States, urban and suburban growth. According to the American Farmland Trust, by 2040 some 18.4 million acres (nearly the size of South Carolina) will be lost to residential and industrial development. Nearly two-thirds of that farmland is managed by people over 55, and young people face economic hurdles to getting started—one of the main reasons that farmland is sold for development rather than continuing to be farmed.

Top among the American Farmland Trust's recommendations is “smart solar” practices that include incentivizing agrivoltaics to make farming more profitable and affordable for the next generation of food producers.

Resolving Land Use Disputes

Land use issues are often critical to further solar development. Renewable energy requires on average 10 times more land than fossil fuels do per unit of energy. Moreover, solar panels are site-constrained, needing to be sited where the sun shines, whereas fossil fuels can be transported and burned in areas less exposed to human interaction, or close to low-income communities and communities of color whose voices are often ignored in siting decisions.

Because “distributed energy resources” like solar are visible to a wider public, solar development can give rise to public opposition that captures the attention of the media and politicians. Increased reliance on solar energy can also create “green on green” tensions, pitting the preservation of rural biodiversity against the promotion of clean energy—tensions that agrivoltaics can alleviate. By preserving farmland while expanding solar development, the economic and racial injustice of fossil fuel use is also reduced.

Agrivoltaic Projects

While suggestions of combining solar energy with agriculture date back to the 1980s, agrivoltaics as a word and a practice dates back to the first decade of the 21st century. To date, most agrivoltaic projects are small-scale, still in the research and development stage, with a few operations reaching commercial success.

The Department of Energy's National Renewable Energy Laboratory (NREL) lists over two dozen project sites participating in its InSPIRE (Innovative Site Preparation and Impact Reductions on the Environment) program, covering projects from pollinator-friendly wildflowers to tomatoes.

Livestock

One of the most common integrations of agriculture with solar panels, and the one that offers the greatest potential for electricity generation, is allowing animals to graze on the land beneath solar panels. This can be done at scale without the need for large farm equipment.

Livestock grazing also has the benefit of controlling vegetation growth underneath the panels. Due to their size, sheep are well-suited for browsing under panels, but when panels are raised high enough, cows can be accommodated as well. Given that dairy cows consume on average 25 gallons of water per day, the water-saving benefits of solar panels can be enormous.

Crops

Many agrivoltaic projects also involve either intensive horticulture (fruits and vegetables) or cereal and legume production. Solar panels have been installed above vineyards in Italy and India, for example. In Belgium, shade-tolerant potatoes are promoted as a potential driver of agrivoltaic growth.

In the United States, low-bush blueberries growing in Maine have proven suitable for agrivoltaics. In Arizona, a project outside Biosphere 2 grows chard, kale, cabbage, onions, and other plants that prosper in partial shade. And among the many other projects, researchers at the University of Illinois Urbana-Champaign grow row crops, forage, and specialty crops in order to diversify the state's reliance on corn and soy.

Challenges of Agrivoltaics

Agrivoltaics is not without its challenges. Rainwater runoff from solar panels alters the distribution of water on a farm, potentially affecting crop growth. Increased humidity under the panels, due to decreased evaporation, can introduce diseases or parasites. And, perhaps most importantly, the investment costs of a solar photovoltaic system present an obstacle to many farming operations.

Addressing these challenges can help agrivoltaic systems progress, improving both the food and energy security of communities that adopt this practice.