Backup Power for Hawaii: Island Grids With Nowhere to Borrow From

August 2023. Wind-driven wildfire destroyed Lahaina on Maui, killed over a hundred people, and put Hawaiian Electric's lines at the centre of the investigation into how it started. verify The utility's response was to adopt planned shutoffs — cutting power in advance when the wind blows and the grass is dry, the way California has done for years.

Hawaii backup planning starts with a fact no mainland state has to think about: each island is on its own.

Why Hawaii is its own problem

Isolated grids. Oahu, Maui, Hawaii Island, Kauai, Molokai and Lanai each run a separate grid with no connection to each other or to anything else. When Texas is in trouble it borrows from Oklahoma. When Maui is in trouble, there is nobody to borrow from.

Planned shutoffs are new. Since Lahaina, Hawaiian Electric cuts power pre-emptively in high-wind, dry conditions. verify They are announced in advance and they can last a day or more.

Fuel is shipped in. Hawaii's electricity is among the most expensive in the country because it runs largely on imported oil. verify Generator fuel is expensive in normal times and scarce after a storm.

The sun is constant. The advantage. Year-round strong sun and mild temperatures mean a battery-plus-panel setup is genuinely self-sustaining here.

Hurricanes, occasionally. Iniki in 1992 left Kauai dark for weeks. verify Direct hits are rare, but the season runs June to November.

Think of it as a small solar system

The mainland advice — charge from the wall before the storm — assumes the grid comes back in a day. On an island with no neighbour to borrow from, it may not, and the fuel for a generator may not either.

The setup that fits: a 1,000–2,000Wh unit and 400W of folding panels on the lanai. The panels refill the battery by afternoon. The battery runs fans, the fridge, phones and internet overnight. Repeat.

Treat those hours as per charge. With panels in Hawaii sun, the fridge and fans run indefinitely.

Heat and humidity

Hawaii is mild, but a house without fans in August is uncomfortable and a week of it is worse. Fans, not AC — a box fan on a battery runs for a day, and a window unit empties a 2,000Wh pack in hours. Trade winds and open windows do most of the work.

The generator question

A generator gives more power, and it is a reasonable first-days tool if you have fuel stored. But island fuel is expensive, shipped in, and gone after a major storm. The battery with panels is the plan that needs nothing delivered. Puerto Rico's guide covers the same island logic in more depth.

What we'd buy, by situation

Honolulu, Oahu — apartments and houses

A 1,000Wh unit and 400W of panels. The EcoFlow DELTA 2 with two PV200s on the lanai. For an apartment without outdoor space, a smaller unit and the apartment guide.

Maui, Hawaii Island, Kauai — longer restorations, shutoff zones

2,000Wh class plus panels. The Bluetti AC200L. Neighbour islands restore more slowly, and the shutoff zones need a full day of self-sufficiency.

Off-grid or catchment-water households

The whole-home conversation. Many neighbour-island homes are on catchment water with an electric pump, which is the well-pump problem by another name.

What not to buy in Hawaii

A battery without panels. On an island with this much sun and this little spare fuel, it is the wrong shape.

A generator as the only plan. It needs fuel that is expensive now and absent after a storm.

A unit stored in a hot carport. Heat ages lithium fast. Keep it in the coolest room.

The free things, which matter most

Sign up for Hawaiian Electric's shutoff alerts. The notice only helps if it reaches you.

Freeze water constantly. A full freezer holds for days.

Keep the panels clean. Salt air and volcanic dust cut output. A wipe every week is free watts.

Know your evacuation route if you live in a wind-and-grass area. Lahaina proved that fire moves faster than a car in traffic.