Tesla’s recent announcement that it’s introducing a home battery created a stir, and a surge of people have already bought them.

During a conference call with investors and journalists on May 6, Tesla CEO Elon Musk said that his company is already seeing a high demand for its Powerwall device. Thus far, an excess of 38,000 consumer Powerwalls have been requested, and Musk calls it all “overwhelming,” according to Ars Technica.

The Powerwall is a home battery that charges using electricity generated from solar panels, making it a sustainable and environmentally friendly resource. Users without solar panels can also charge the batteries when utility rates are low. If you live in an area where power outages are frequent or you simply want a backup, the Powerwall can serve as your additional power source in the event that your house goes dark.

The Powerwall itself can be wall-mounted, and it includes a rechargeable lithium ion battery with liquid thermal control. The 10-kilowatt-hours weekly cycle version is $3,500, and the seven kilowatt-hours is available for $3,000. It provides two kilowatt-hours of continuous power and up to 450 volts of electricity. Whether you want to power your TV, light fixtures, or laptop, it can be seamlessly done with the Powerwall. If you’re trying to run a lot of power-sucking appliances at once, however, that Powerwall’s ability can max out, though the batteries do stack, for users looking to utilize their solar panels to power their homes.

“There’s no way that we could possibly satisfy this demand this year, and we’re basically sold out through the middle of next year,” said Musk during the call. It may not go mainstream just yet, but the Powerwall’s early success suggests many consumers want to harness their own resources, rather than rely on the services of other companies.