Agrivoltaics—the practice of using the same piece of land simultaneously for agriculture and solar power generation—has enjoyed a lot of positive press lately. We spoke with Renee Robin of Broad Reach Power and farmer and solar energy developer Jon Reiter about whether agrivoltaics is right for California.
Can you describe agrivoltaics?
Jon Reiter: Agrivoltaics can mean commercial farming between rows of solar panels, livestock grazing below solar panels, or planting cover crops below solar panels.
Renee Robin: For me, agrivoltaics means dual-use solar with food production. This could also include crops that support pollinators, grazing, or habitat restoration.
Many folks think agrivoltaics has limited applicability in California’s agricultural systems. Why? What are the challenges, and how might we address them?
JR: I don’t anticipate substantial agrivoltaics in California. You can’t plant permanent crops—like almonds, pistachios, wine grapes, and citrus—between solar rows. Some specialty crops, like tomatoes, are row crops, but they have large harvesters. It would be cost ineffective to commercially farm such crops between solar panels.
Grazing is a good way to address weed abatement, but animals can harm the solar array by bumping into it or chewing wires—and even causing fires. The most viable option may be cover cropping. Cover crops can suppress dust, protect air quality, support pollinators, and return nutrients to the soil, which keeps the land ready for a return to cultivation. When some solar projects are decommissioned after a few decades, it would be good to have that land in a farm-ready state.
However, several groundwater sustainability plans count precipitation in their water budget, which defines how much water is available in a subbasin. So, even if you grow cover crops with precipitation alone, many GSAs will consider that water consumed within the service area, so it counts against the water budget. That’s the most significant negative.
RR: If you separately put 100 acres in solar and 100 acres in agriculture, you’ll get 100% of yield for that use on both properties. However, if you combine them on a single 100-acre plot, you might get 80% of the yield for each use, which means you’re getting more productivity per acre: 160% yield on dual-use parcels.
The size of harvesters has been a concern in the past, but you can space the arrays so that equipment can get through, and you can make the piers that support the arrays taller—though this uses more steel and is therefore more expensive. For grazing, successful design modifications include enclosing cable trays so sheep or goats can’t get to them. Managed grazing can be coupled with a habitat management plan to benefit endangered species.
The global energy company AES has over 5,000 acres of dual-use solar and grazing in California, and a number of companies around the world are planting row crops under shade structures. In areas that are becoming less suitable for agriculture because of climate change, dual-use solar that provides shade (which can also reduce crops’ water needs) might actually give these lands a longer agricultural life.
Groundwater recharge should be considered an additional category for agrivoltaics. While most solar projects aren’t sited on good recharge lands (nor should they be), in years like 2017 or 2023 that were very wet, the opportunity to recharge on solar land would be tremendous. Developing programs and procedures for recharge under solar would be good to eliminate the stigma. In my view, the resistance to dual-use projects has been political, rather than practical.
JR: I see it as an economic issue, not a political issue. When I started developing farmland for utility-scale solar projects 15 years ago, there was political resistance. Now, countless landowners contact me almost daily to develop their sites because of water concerns. The stigma of solar in the San Joaquin Valley has subsided, and now people understand the opportunity of developing renewables.
In California, we don’t have a shortage of land, but we do have a shortage of water. If a landowner has available water to farm, they have vast options of land that’s ready to plant in water-stressed areas like Kern, Madera, and western Fresno counties. Instead of getting 80% farming yield on the solar site, they can capture full yield on the agricultural land and full revenue from the solar site. I think landowners understand this and this is driving decisions away from agrivoltaics.
What kinds of policy changes might help boost agrivoltaics?
JR: We want nutrients in the soil, we want to reduce erosion, and we want good air quality. If this is determined to be an important state objective, and solar developers and landowners were told they’d get paid to use precious water to grow cover crops, that commercializes the cover crop. This could encourage cover crops under a solar facility and more generally across fallowed farmland.
RR: In many counties, Williamson Act programs treat solar on agricultural land as a conversion out of agriculture, which means the landowner is subject to large fees if the land comes out of Williamson Act contract early. Each county writes its own local rules on the Williamson Act, and different counties are interpreting it in different ways.
Do we make this uniform for counties, or do we have the state, through the Department of Conservation, define it as when a commercial agricultural use remains on the property? If you can demonstrate that doing a dual-use project results in measurable water conservation, for instance, should there be incentives to do that?
JR: I feel like a Debbie Downer on this—I’m a bit of a naysayer. Water is going to go to the highest, best, and most efficient use. I don’t know if agrivoltaics meets that standard here in California.
RR: I would love California to see agrivoltaics as an opportunity, rather than a conflict in use. In my mind, that’s the future of both industries in California.