Apple CEO Tim Cook said today that his company will partner with First Solar to build a $850 million solar energy farm in Monterey County, California.

First Solar’s stock closed 5 percent higher, and it continued to rise in after-hours trading this afternoon.

Apple says the farm will generate enough energy to power 60,000 homes.

Cook mentioned the new solar project during a wider conversation about Apple’ products and business at the Goldman Sachs Technology and Internet Conference.

Apple already operates two solar energy farms in North Carolina and one in Nevada.

Cook has stressed that Apple’s data centers run on renewable energy sources. The company has said that it wants all its corporate offices, retail stores, and data centers to run entirely on renewable sources like solar, wind, micro‑hydro, and geothermal, which uses heat right from the Earth.

Apple announced just last week that it would open a new $2 billion data center in Arizona, powered by solar. The center is being built on the site of a former Apple supplier of sapphire glass, GT Advanced.