Hundreds of used electric vehicle battery packs are enjoying a second life at a California facility connected to the state’s power grid, according to a company pioneering technology it says will dramatically lower the cost of storing carbon-free energy.

Home solar panels had already been chipping away at the United States’ centralized power system, forcing utilities to make electricity transfer a two-way street. More recently, home batteries have allowed households with solar arrays to become energy traders, recharging when electricity prices are low, replacing grid power when prices are high, and then selling electricity for a profit during peak hours.

Tesla has managed to cut the price of its electric cars in half over five years, and it might do it again with its next-generation vehicle platform.

Electric vehicle startups Polestar Automative Holding and Rivian Automotive Inc. are known for doggedly tracking their individual corporate emissions, detailing the environmental toll of everything from the lights in their factories to the rubber in their cars’ tires. On Wednesday, the EV rivals paired up with consulting giant Kearney to raise a flag on the industry more broadly: In a new report, they argue that the transition to electric vehicles alone won’t be enough of a solution to meet the emissions threshold laid out in the Paris Agreement.

Sales of electrified cars plunged in Germany in January as government incentives to encourage buyers were scaled back. Tesla bucked the downward trend by boosting volume through price cuts.