If you recall, the SolarCity buyout allowed Elon Musk to open up Tesla Energy. This is where Tesla focuses on a lot of energy-efficient products. While this did include solar energy products, it also included a lot of residential material that could be used to store electricity. The Tesla Powerwall is a rechargeable lithium-ion battery that stores electricity for solar self-consumption. This can be crucial because solar panels only do so much. Most of the time, the panels only power things up when they have the sun directly on them. Most places that sold solar energy panels did not offer any sort of energy storage unit that was worth your time.
This allowed the Tesla Powerwall to really become an asset as it stored that solar energy where your home could gather up all the solar energy panels could manage during the day. Yet what your home was not using could then be stored in the Powerwall as backup power. When it first came out in 2015, the production was limited but mass production began in 2017. By Spring 2021, Tesla installed as many as 200,000 Powerwalls. Musk was not responsible for the design of this either. The inventor was Arch Rao, who was Tesla’s Head of Product at the time. Today, they have also produced even larger and more efficient Powerwalls than the original.