a16z backs Base Power in $200M round for home backup batteries

In less than a year, Base Power has grown from a stealthy startup to one of the largest battery fleets in Texas.

Now, the company has raised $200 million to fund a rapid expansion, including dozens more megawatt-hours of battery storage and plans for a domestic battery factory.

The Series B round was led by Addition, Andreessen Horowitz, Lightspeed Venture Partners, and Valor Equity Partners. Altimeter, Terrain, Thrive Ventures, and Trust Ventures participated.

Backup batteries are nothing new — Tesla has been selling its Powerwall for nearly a decade — but Base Power takes the model to new territory. First, its batteries are massive, 25 or 50 kilowatt-hours, almost double or quadruple a single Powerwall, respectively. Then there’s the cost: Base Power charges just $595 or $995 up front depending on the capacity, while a single Powerwall will run about $15,000 or more before incentives.

The hitch? Customers have to commit to buying electricity from the company for three years at 9 cents per kilowatt-hour plus whatever delivery fees the local utility charges. They also have to pay an annual fee, which ranges from $225 to $345. For the average Texas household, the fee adds around 2 cents per kilowatt-hour.

For Base Power, the real money is almost certainly in so-called grid-balancing operations. Thanks to the way Texas’s power market works, the startup can be paid — handsomely in some cases — to tap the batteries it has installed to send electricity back to the grid.

By installing residential batteries, Base Power appears to have found a speedy way to build a megawatt-class fleet of batteries, sometimes called a virtual power plant. While Texas is home to a growing number of massive grid-scale battery facilities, they can take years to plan, permit, and built.

But residential batteries can be permitted and installed in a matter of weeks. Base Power installed 10 megawatt-hours last in March, co-founder and CEO Zach Dell told Canary Media. The company plans to hit the 100 megawatt-hour mark sometime this summer.

The new funding will go toward speeding installations and expanding into new states. It’ll also go toward starting construction on a battery factory in the U.S., an endeavor that could partially insulate it from the threat of tariffs but also introduce a new flavor of risk. Battery factories have proven challenging to master, and other companies have hit rough patches when attempting the same.