See Tesla built a huge solar energy plant on the island of Kauai (The Verge) for more details; tangentially, see Will electric cars soon have solar roofs? Toyota and Tesla say yes. (ThinkProgress)
"On Wednesday, Tesla and the electricity cooperative that serves the Hawaiian island of Kauai opened a 13 MW solar farm combined with a 52 MWh battery installation to help the island reduce its fossil fuel consumption by about 1.6 million gallons of diesel and petroleum per year.
The batteries are intended to store Kauai’s abundant solar energy resources during the day and dispatch them when necessary, often at night. Solar City, the solar panel company that Tesla bought last year, built a similar installation on the island of Ta’u in American Samoa. That system serves 600 people. In California, several battery-making companies, including Tesla and AES Energy Storage, have built battery storage for that state’s grid, too. (Although in California’s case, while the batteries allow for more renewables to be added to the grid, the batteries aren’t necessarily tied to renewable energy, so all kinds of electricity is stored equally for dispatch during periods of electricity shortage)."Kauai is moving from diesel generators to renewable energy with help from Tesla | Ars Technica