Energy Storage is a major challenge for the renewable-energy industry. With sufficient storage, when the sun isn’t shining or wind isn’t blowing, intermittent power generation wouldn’t be such an issue.


Ta’u, a small island in American Samoa, now gathers enough solar energy for 24/7 power, thanks to a microgrid project completed in November with solar provider SolarCity and Tesla. 


The system, operated by American Samoa Power Authority, comprises 5,000 SolarCity solar panels and 60 Tesla Powerpack battery-storage systems. It has 6 megawatt-hours of battery storage and can fully recharge in seven hours of sunlight. SolarCity implemented the microgrid in one year, according to the company blog.


Ta’u switched from diesel generators to 100 percent renewable energy with the microgrid, according to an article in the Pittsburgh Post-Gazette. The microgrid has 1.4 megawatts of solar generation capacity and can power the entire 17-square-mile island for a full day and night.


Providing power to a remote island can be difficult. Ta’u, with a population of 1,000, has been relying on diesel generators. Fuel for the generators had to be shipped in by boat, a very expensive endeavor. The island often ran low on fuel before the next shipment arrived and had to ration power or face outages.


“This is part of making history,” said Ta’u resident Keith Ahsoon in the SolarCity blog post. “This project will help lessen the carbon footprint of the world.”


Now with the microgrid, the island can stay powered for three full days without the sun. Ta’u hospitals, schools, fire and police stations and local businesses no longer need to worry about outages or rationing. Power outages are now unlikely, and intermittent electricity will not be as much of an issue.


“When we think about large-scale solar-power systems going forward, into the next decade, we see them all as having these [battery systems] attached to them,” said Peter Rive, SolarCity co-founder and chief technology officer.


With the SolarCity-Tesla battery-coupled system, energy can be stored and dispatched even if the sun isn’t out. So far, the microgrid has met 99 percent of Ta’u’s power needs.


The switch to solar energy limits costs and greenhouse gas emissions. The microgrid system could save the island almost 110,000 gallons of diesel fuel annually, or about 2.5 million pounds of carbon dioxide emissions per year, according to the Post-Gazette article.


For more, visit http://blog.solarcity.com/island-in-the-sun.