Last week, Shell became the latest supermajor to make a big bet on battery storage with the announced acquisition of German energy storage startup Sonnen. Sonnen focuses specifically on household energy storage, a nascent market but one with a huge potential if ambitious renewable power plans by governments around the world work out.

Household energy storage has not garnered as much attention as EV batteries, but it has a bright future as rooftop solar installations become increasingly popular in places like Europe, Australia, and North America and especially as the prices for such household storage installations decline.

Despite the drawbacks, however, Shell’s announcement is the latest sign Big Oil is getting increasingly interested in batteries as part of its preparation for a more renewable energy future.

Solid-state batteries are a fascinating segment of the battery industry with proponents arguing they can replace lithium-ion batteries with their liquid electrolytes and solve the problems arising from this fact. In short, solid-state batteries hold significant promise.