Despite issues with its Solar Roof, Tesla's Powerwall has apparently been a hot-selling item over the last year. The company announced on Twitter that it has sold over 200,000 Powerwall units so far, around double the number it said it had sold at this time in 2020.
Powerwall gives solar panel and other customers a powerful battery backup when the power (or sun) goes down. That has saved some customers during outages, as Twitter user Andru Edwards noted in the tweet that Tesla quoted. "The neighbors started texting asking how my lights were on," he said. Tesla CEO Elon Musk also suggested that power utilities might, in the future, be able to tap Powerwalls to release stored electricity back to the grid during storms like the one that hit Texas in April.
It could apparently be shipping even larger numbers if it could manufacture more of them. Tesla recently said during its first-quarter earnings call that it had a "multi-quarter backlog on Powerwall." It also announced in April that it would no longer sell its Solar Roof panels without a Powerwall unit, which ought to boost demand even further.
Tesla recently unveiled the Powerwall+, an updated version that can supply up to 9.6kW of power, up from 5kW continuous and 7kW of peak output. That will allow folks to power more things or larger houses, though the battery would drain quicker as it still holds the same 13.5kWh of charge.