As California faces pressure to grow both food and energy while protecting biodiversity — all on a finite amount of land — a trend is emerging in the field of clean energy: multi-use solar projects, or sustainable voltaics.

A report, released today by the Wild Energy Center, a program of the Energy and Efficiency Institute at the University of California, Davis, defines such projects and describes the challenges and opportunities they present for the state’s landscapes.

A defining moment

The authors term these projects “voltaic landscapes for sustainability,” which generate solar energy while cultivating additional outcomes:

• “Agrivoltaic solar farms” produce crops. 
• “Rangevoltaic solar ranches” host grazing livestock, such as sheep.
• “Ecovoltaic solar parks” increase habitat for biodiversity and other ecosystem services.

“We are excited to define and present these three unique opportunities in a manner that can effectively catalyze their development,” said Wild Energy Center Director Rebecca R. Hernandez, a professor in the UC Davis Department of Land, Air and Water Resources. “For example, most people understand that national parks preserve natural resources, and thus using the term ‘park’ to describe an ‘ecovoltaic solar park’ that has restored native biodiversity mirrors that long-standing naming convention. Similarly, if I were to visit a ‘farm,’ I would assume it grows some type of crop. We can expect the same from an agrivoltaic solar ‘farm.’” 

Expanding capacity and inclusion

The report empowers multi-use solar leaders to showcase options beyond conventional solar energy development to stakeholders, including developers and policymakers, who may not be aware of their benefits. The report also includes best practices for each multi-use solar type based on scientific evidence and expertise from the Wild Energy Center’s partners. 

The report suggests that including experts beyond engineers, developers and financiers is most effective to realize multi-use voltaic landscapes. For example, a rangevoltaic solar ranch designed and operated in collaboration with graziers could ensure that livestock will have appropriate fencing, healthy forage and access to clean water.

Other topics in the report range from environmental justice and enhancing community engagement to increasing soil health and reducing herbicides. 

The authors also present results from a roundtable discussion with five solar industry stakeholders to identify common benefits and barriers to sustainable voltaics.

“We need to solve multiple problems at once: We need to produce low-carbon energy and sustainable food, all while increasing habitat for biodiversity,” said Hernandez. “There is a lack of off-the-shelf guidance on how exactly to do this. We want to give those in the driver’s seat more legitimacy and a bit more capacity for boldness. This is the future energy landscape we desire and need.”

Support and interest, but cost concerns

The solar industry professionals who shared their perspectives had experience with grazing sheep alongside solar and were interested in expanding into other voltaic landscapes, such as cattle grazing, beekeeping and row crop production.

They also noted strong public support for multi-use solar energy development. For example, a 2022 study found nearly 82% of respondents were more likely to support solar energy development in their community if it incorporated agricultural production.

Additional costs were their main concern. While incorporating multi-use solar projects into the early planning stages of a project can help minimize costs, the report said adoption incentives and regulatory rewards may be most effective in encouraging those considering sustainable voltaic landscapes to take the leap. 

Practical support

The Wild Energy Center aims to quantify a range of added costs involved with developing agrivoltaics and ecovoltaic systems to offer practical support to the industry. The center also continues to investigate questions around voltaics and pollinators, soil carbon and public opinion.

“We want to get this research into the hands of communities and developers,” said co-author Ben Finkelor, executive director of the Energy and Efficiency Institute at UC Davis. “Then, they can have a conversation using a common language while understanding the tradeoffs so we can continue to develop best practices.” 

The report and other science communication efforts by the UC Davis Wild Energy Center are funded through a California Climate Action Seed Grant awarded by the UC Office of the President to increase public access to the latest scientific research.

Additional co-authors include Thomas Patten, Yudi Li, Michael O. Levin, Daphne Condon, Noah Z. Krasner, Nick Tew, Uzma Ashraf and Elliott Steele of UC Davis. 

Subscribe to the Science & Climate newsletter