Living on solar power in Hawaii means free, abundant power most of the year. The return on investment here happens much faster than in other parts of the country. Situated just above the equator, Hawaii gets a lot of sun even in winter, which of course is one of the reasons it is America’s beach. In addition, power rates in the islands are the highest in the country and climbing. But what happens during periods of dark clouds and stormy weather like last week?

Heavy rain and storms often cause the Maui County power grid, which is supplied by hulking diesel-powered generators, to crash as it did last week. Most of the island went dark. However, at my off-grid house, we still had power thanks to our independent solar system. But what good are solar panels when not even a shadow of the sun is visible?

I went out to the power box at least every hour to check. According to the power meter, the solar panels were delivering juice to the batteries even under dark, thundering clouds. On the worst day of the storm, the panels brought down 1 kilowatt hour–more than our gas generator would had it been running all day and enough to power lights, the water pump and WIFI. Despite the storm, we still had power.