This story has been updated to reflect NRG Energy's deal with Whole Foods.
Alternative energy company SolarCity, co-founded by Elon Musk, has entered a deal to fit up to 100 Whole Foods Market stores—roughly a fourth of the supermarket chain's 431 locations—with solar panels. Whole Foods has also contracted with NRG Energy (nrg) to provide panels in up to 84 of those 100 locations. Shares of NRG are down 5%.
"SolarCity will custom design each solar power system to maximize the amount of grid power offset and expects to begin installation this spring," the two companies stated in a joint press release. "Whole Foods Market will also save money with the new solar installations by purchasing power from SolarCity at a discount to current electricity costs, locking in low solar energy rates for years into the future."
Once completed, Whole Foods is expected to place in the top 25 corporate solar users in the nation, as ranked by the Solar Energy Industries Association, flanked by cohorts such as Walmart (wmt) and Costco (cost) .
The deal is welcome news for SolarCity, which has had a rough start to the year alongside the rest of the solar energy industry and missed its fourth-quarter guidance. At the time, the company cited unforeseen delays in commercial contracts as well as its abrupt decision to stop doing business in Nevada. "The decision came after the state regulator there decided to change an important policy that made solar installations attractive to customers by paying them for the energy they produced," Fortune reported last month.