Electric Car Batteries Get a Second Life Storing Solar Power

A California energy startup has turned more than a thousand electric vehicle batteries into solar power storage capsules — proving out a compelling alternative to traditional battery recycling.

Why It Matters

Electric cars are cleaner than gas vehicles, but their batteries carry a significant ecological footprint from mining and manufacturing. Repurposing old EV batteries maximizes their useful life and squeezes more value out of each one made. At the same time, energy storage helps solve solar power's intermittency problem — batteries can store solar energy to be used when the sun isn't shining, smoothing out supply and demand on the grid.

B2U Storage Solutions' Sierra Facility

B2U Storage Solutions' Sierra facility in Lancaster, California has reached 25 MWh of solar storage capacity using second-life EV batteries from Honda and Nissan. During the day, the facility's batteries are charged by nearby solar panels. At night, when solar rates are higher, the company sells that stored power back to the grid. The facility generated over $1 million in revenue in its first year of operation.

B2U's key breakthrough is a proprietary plug-and-play technology that leverages battery packs' existing battery management systems. According to co-founder and president Freeman Hall, this approach "virtually eliminates the repurposing costs" and makes the operation highly scalable. Because the job of storing solar power is far less demanding than powering a moving vehicle, the batteries are subjected to only a fraction of their rated current and kept within conservative voltage ranges — translating into a long and productive second lifespan.

The Bigger Picture

While 25 MWh is modest compared to the world's largest solar storage facilities, the Sierra project's purpose is demonstration, not scale — to build the track record and dataset needed to prove second-life batteries can serve as reliable, cost-effective solar storage. As more early EV owners upgrade to newer models over the coming years, the available supply of used batteries is expected to skyrocket, creating vast potential for repurposing programs like this one.

Battery recycling firms like Redwood Materials and Lithion are also gaining traction. Other potential second-life use cases are emerging as well — car manufacturers may explore the technology to decarbonize their production lines, while airports and airlines have also shown interest in small-scale onsite energy storage.

Originally published by Axios. Author: Alex Fitzpatrick.