In a 2022 Brazil trial, 52 lambs spent 60 days under solar-panel shade; researchers reported lower body temperatures and about 4% better feed efficiency on hotter days

The sun can either be a valuable tool or a challenge for farms. Between May and June of 2022, researchers from São Paulo State University ran a 60-day field trial in Brazil, comparing 52 crossbred lambs that got shade from overhead solar panels against lambs that didn't. The results were only written up years later, in a paper titled "Animal agrivoltaics facilitates the sustainable intensification of sheep production in tropical areas," published in the journal Small Ruminant Research.

The logic behind this experiment seemed fairly straightforward: if solar panels had to be under the sun, then why couldn’t the sheep stand under the solar panel? As for the outcome, the lambs that received shade had body temperatures about 0.7°C lower and roughly 4% better feed efficiency than the unshaded lambs on the hot days.

Detailed account of what happened in that Brazil trial


Between May and June of 2022, researchers divided 52 crossbred lambs into two groups. One group was provided shade through 20 solar panels installed above their enclosures, while the other group did not receive any shade and was left to stand directly under the sun. Over the course of 60 days, on the days when temperatures were comparatively higher, between 10 a.m. and 2 p.m., subcutaneous body temperature of the shaded lambs was observed to be roughly 0.7°C lower than that of the lambs exposed to sunlight. The paper reports this difference, along with the shaded lambs' lower respiratory rate, as statistically significant at P = 0.0001.

Furthermore, the shaded lambs tended to spend more time resting and ruminating (in other words, chewing cud and relaxing); they consumed less feed and gained weight 4% more efficiently than the other group of lambs (also reported as statistically significant, at P = 0.0002). To put it simply, lower stress in animals led to less food waste and increased production efficiency. That efficiency gain was about the animals; the solar structure itself had a separate, unrelated payoff on the electricity side. Over the 60-day trial it generated 2.3 MWh, and the paper projects 13.70 MWh a year from a structure of that size, enough, researchers calculated, to avoid about 7.2 tons of CO2-equivalent emissions annually.

Why this matters way beyond a Brazilian feedlot

It's worth being clear about what kind of setup this was: the Brazil trial used fixed, roof-like panels built directly over confinement pens, essentially swapping a shade structure for a power-generating one. That's a different arrangement from the open-pasture "solar grazing" now expanding across the United States, where sheep roam freely among ground-mounted panel rows rather than living in a shaded pen beneath them. Even so, both approaches point toward the same basic idea: using the same land for livestock and solar power at once, instead of choosing between them. In a 2021 study titled “Herbage Yield, Lamb Growth and Foraging Behavior in Agrivoltaic Production System,” published in Frontiers in Sustainable Food Systems, Oregon State University researchers conducted an experiment that lasted for two years and demonstrated that lambs under solar panels gained weight almost as fast as lambs raised in an open area, but at the same time, the plot of land served for the production of food and energy.

Solar grazing itself, meanwhile, has grown quickly in the U.S.: a first-of-its-kind 2024 census by the National Renewable Energy Laboratory and the American Solar Grazing Association found about 113,050 sheep grazing roughly 129,000 acres across more than 500 solar sites in 30 states, nearly nine times the roughly 15,000 acres the industry had estimated just three years earlier. "Solar grazing," a practice of shepherding animals that serve for cutting grass under the panels in lieu of mechanical mowers powered by diesel fuel, developed from just a hobby into an actual industry. Texas alone has ranchers grazing thousands of sheep at solar installations; the same 2024 census counted roughly 68,000–70,000 acres of Texas solar sites under grazing, and individual operators there, like Texas Solar Sheep and rancher Ely Valdez's flock of over 10,000 head, now run some of the largest solar-grazing operations in the country.

The part nobody's hyping enough

The Brazil study actually has a small sample size: only 52 animals at one place, from one breed and during one season of the year. Although the 0.7-degree decrease in temperature and 4 percent gain in feed efficiency were statistically significant (P = 0.0001 and P = 0.0002, respectively, per the published paper), the sample was small, and the findings should be interpreted cautiously. Brazil's trial site sits in a tropical climate, which differs enough from the temperate climates of, say, Ohio or Texas that the exact numbers may not transfer directly, though across different countries and studies, shaded areas are cooler and may improve cattle performance.

There are larger questions that remain unanswered; questions about cost-effectiveness and logistics, not biology. US-based solar grazers have already noted that having water, fences, and proper site layout are the key factors, not the panels themselves. Shade would be great, but one may still have to keep the animals in mind when designing the infrastructure, rather than retrofitting it after the fact. It is not a complete solution to heat stress in industrial farming or to the climate emergency. This is an incremental step that fits into a growing solar grazing trend. With extreme-heat days already becoming more frequent in much of the U.S., according to NOAA climate data, designing solar farms with animal welfare in mind could be a practical step forward.