Co-location of sheep grazing and solar energy production yields agrotechnological synergies

Abstract

Context

Agrivoltaics—the co-location of solar energy and agricultural production—may reduce land-use competition and boost revenues for landowners. Sheep grazing in solar facilities (i.e., solar grazing/agrivoltaic grazing systems) is increasingly common in agricultural areas. Solar grazing can provide land access to flock owners and support agricultural viability via payments for vegetation management. However, there is a need for more data on how co-location of sheep grazing and solar energy production affects flock health, stocking rates, and feedback loops for maintenance of vegetation in solar facilities across regions.

Objective

Our objective was to better understand synergies and trade-offs associated with agrivoltaic grazing systems by investigating applied grazing management questions and concepts regarding agrotechnological co-benefits related to simultaneous flock health and vegetation management in solar facilities.

Methods

We tested effects of sheep stocking rates (0 to 10 sheep per ha⁻¹), site preparation (fallow vs. legume seed-mix planting), and microclimate (panel-shaded areas vs. panel interspaces) on herbage yield and nutritional quality, flock health and condition, and a vegetation management success index. We collected these data across two grazing seasons in an operational, 21.85-ha photovoltaic solar facility (18 MW) established on a previous old field in New York State, USA.

Results and conclusions

Shade from solar panels negatively affected herbage yield. We detected no significant differences in herbage yield or vegetation management outcomes between fallow and planted legume plots, suggesting that regrowth from native seed banks in solar facilities on previous old fields may be an economical alternative to seeding for sheep forage. Sheep stocking rates affected flock health and condition; we identified an optimal stocking rate of 8 sheep per ha⁻¹ for achieving sufficient herbage yield and quality, maintaining flock health, and preventing vegetation overgrowth from shading solar panels at our study site. Solar grazing can yield an agrotechnological synergy supporting healthy forage, healthy sheep, and vegetation management in community-scale (i.e., <25 MW) solar facilities without mowing. In a well-managed solar grazing system, high herbage yield and quality promote high flock health and condition, and the healthy flock suppresses vegetation enough to prevent panel shading without mowing.

Significance

Our study highlights the potential for sheep grazing in solar facilities to simultaneously benefit sheep and solar energy production systems. Solar grazing can present a “win-win" scenario for solar developers and sheep producers in the northeastern U.S.