The new solar project on Ta’u. (Photo courtesy of SolarCity.)

A small island in American Samoa is making the switch from diesel generators to 100 percent renewable energy. Ta’u, the easternmost of the Samoan islands, has just been equipped with a new microgrid with 1.4 megawatts of solar-generation capacity and six megawatt hours of battery storage. It’s enough to power the entire island night and day.  

With an area of just 17 square miles, Ta’u has a population of fewer than 1,000 people, and until now, they have relied almost entirely on diesel generators for their electricity. But it hasn’t always been an ideal situation. Because Ta’u is so remote, fuel for the generators must be shipped in by boat, which is expensive and means the island sometimes runs low on fuel before the next shipment arrives.

About a year ago, the American Samoa Power Authority began soliciting help with a project that would save the island the inconvenience, costs and greenhouse gas emissions associated with relying on diesel.

“[They] basically just put out a solicitation to see if anybody could provide an alternative to diesel, and that’s something that we responded to,” said Peter Rive, co-founder and chief technology officer of solar provider SolarCity, which was recently acquired by Tesla.

The result is a system composed of more than 5,000 SolarCity solar panels and 60 Tesla Powerpack battery storage systems. The new microgrid could save the island nearly 110,000 gallons of diesel fuel each year, which amounts to about 2.5 million pounds of carbon dioxide emissions, according to data from the U.S. Energy Information Administration.  

The microgrid is already up and operating, according to Rive, and covering about 99 percent of the island’s power needs. The battery system can provide three full days of power to the island without sun, he added. And it can fully recharge in seven hours of sunlight.

It’s not the first time an island has made the switch to renewable energy. Last year, for instance, the Nature Conservancy completed a $1.2 million solar and wind project on Palmyra Atoll, about 1,000 miles south of Hawaii. Although there’s no permanent population on the atoll, it serves as a scientific outpost and temporary residence for researchers. According to the Nature Conservancy, the island runs almost entirely on renewable energy.

Since 2008, the Galapagos island of San Cristóbal — with the second-largest population in the archipelago — has sourced about 30 percent of its power from wind and solar. And a proposed expansion, announced earlier this year, could boost the share of renewables to 70 percent. The goal is to eventually eliminate the use of fossil fuels in the Galapagos altogether.

SolarCity and Tesla are involved in another project on the Hawaiian island of Kauai, which will finish up with 17 megawatts of solar generation capacity and 52 megawatt hours of battery storage, Rive said.

According to Rive, the future of solar power lies in these types of battery-coupled systems, which allow energy to be stored and dispatched even when the sun isn’t shining. One of the biggest hurdles for renewable energy sources such as wind and solar is that they can only generate power intermittently — when the sun is out or the wind is blowing. The continued development of more effective, fast-responding energy-storage solutions is key to the continued expansion of renewables.

“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,” he said.