Soon, you’ll be able to use BMW i3 batteries to power your house

BMW i battery storage system

Electric cars are becoming more common, and so is a second use for their battery packs. Tesla has made the biggest splash in the energy storage business with its Powerwall and Powerpack stationary battery packs, but Daimler and Nissan have also expressed interest. Now BMW is joining the game with an energy storage system of its own, developed in concert with Germany’s Beck Automation.

Unveiled at the Electric Vehicle Symposium & Exhibition 29 (EVS29) in Montreal, the system uses batteries from the BMW i3. It will be available in 22-kilowatt-hour and 33-kWh sizes, which interestingly enough corresponds to the battery-pack sizes of the current i3 and the longer-range 2017 model that will go on sale later this year. BMW says there is enough capacity to operate “a variety of appliances and entertainment devices” in a home for up to 24 hours.

The carmaker also claims its system will be the first on the market to incorporate “second-life” batteries. These are older batteries removed from electric cars after losing too much storage capacity. Even when they’ve degraded too much for automotive use, lithium-ion battery packs typically have plenty of usable capacity left. BMW will initially use new batteries only, and mix in second-life batteries as they become available.

Read more: LAPD leases 100 BMW i3 electric cars

Investing in energy storage makes sense for automakers not just because it relies on the same battery technology as electric cars, but because it can be beneficial to the owners of those cars. Energy-storage battery packs can collect energy from solar panels that would normally be dumped back into the grid, and store it for later use. Attaching a charging station to that system lets owners lower a car’s overall carbon footprint by ensuring that more of the electricity that powers it comes from a renewable source.

The commercial launch of BMW’s energy storage system comes after years of research into second-life battery uses. Beginning in 2011, the carmaker has engaged in research projects in the U.S. and Germany to test batteries in energy storage. It used batteries salvaged from Mini E electric cars, prototype vehicles that were leased to customers as a pilot program for what became the i3. Last year, BMW also signed a contract with NextEra to supply batteries from its ActiveE test fleet for energy storage.

There’s no word yet on when the BMW home batteries will become available, or how much they will cost. Like Tesla, BMW may pursue both commercial and home applications for its battery packs.