Powerwall is a home battery that charges using electricity generated from solar panels, or when utility rates are low, and powers your home in the evening. It also fortifies your home against power outages by providing a backup electricity supply. Automated, compact and simple to install, Powerwall offers independence from the utility grid and the security of an emergency backup.
The average home uses more electricity in the morning and evening than during the day when solar energy is plentiful. Without a home battery, excess solar energy is often sold to the power company and purchased back in the evening. This mismatch adds demand on power plants and increases carbon emissions. Powerwall bridges this gap between renewable energy supply and demand by making your home’s solar energy available to you when you need it.
Tesla’s newly unveiled system includes the $3,500 Powerwall, a home-based battery pack that can store 10 kilowatt-hours of power. A hair dryer takes about 1 kW to run, while a stove takes several kW to run, so the new system could power a household for several hours, said Stephen Harris, a chemist at Lawrence Berkeley National Laboratory in California, who studies lithium battery technology.
The company is also planning to unveil a business-based battery-storage system, called the Powerpack, though the price for that system has not been released yet. Tesla is already taking orders for its residential system, but the products won’t ship until late summer, company representatives said at the news conference.
The boxes — which are about 33 inches (0.8 meters) wide, 51 inches (1.4 m) tall and 7 inches (17.8 centimeters) deep — are designed to be easy to install, and will connect to the Internet so that users can monitor their power usage.
The technology is probably the same or similar to that found in Tesla’s Model S car, experts say. Although companies are secretive about their technology, most scientists think the Model S uses a particular type of lithium-ion battery in which one layer of the battery, called the cathode, is made of a blend of nickel, manganese and cobalt oxide (NMC).
Lithium ions are interspersed throughout this layer, and when the battery is charged, an electrical current drives the lithium ions out of the cathode, into a fluid filled with electrically conducting ions, and into another layer, called the anode, which is made up of stacks of graphite. When the power stored in the NMC battery is used, it causes the lithium ions to drift back down into the cathode, Paul Shearing, a chemical engineer at University College London, previously told Live Science.
Different battery makers may tinker with the geometry or the particular blend of ingredients, but most researchers think this basic chemistry underlies the Tesla Model S’ battery pack, Cabana said.