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Tesla learns from EVs for home energy storage

Lithium-ion wall unit stores energy for home daily use or back-up during outages

Published: May 3, 2015, 12:30 AM
Updated: July 30, 2015, 7:51 PM

Tesla Powerwall unit with Model S

Tesla in expanding beyond the automotive realm, with the creation of an energy storage unit for the home.

The Tesla Powerwall works much like the electricity storage system in an electric vehicle, with a lithium-ion battery pack storing energy captured by alternative sources (such as solar panels, in this case), and then making it available for use for typical electricity consumption tasks or as a back-up system in the event of a power outage (similar to what the traditional gasoline powered generator does).

The Powerwall takes advantage of solar power, which can’t be used during dark times, by storing the energy for use at a later time. Similarly, it can store energy from the grid during off-peak times for use during peak times. Unlike a generator, it doesn’t run continuously; so, when you run out, you have to wait for it to recapture energy. It can supply 2.0 kW of continuous power, peaking at 3.3 kW.

The system comes in two capacities — 7 or 10 kWh (kilowatt hours) — at a cost in the $3,000-$3,500 US range (roughly $3,650-$4,250 Canadian), with the ability to string up to nine together. It is expected that multiple units would have to be used by households or businesses wanting to go completely off the power grid.

It is estimated that the average household uses between 18 and 40 kWh daily, depending on the season and the number of appliances being used. Large appliances such as refrigerators can use up to 5 kWh per day and washers and dryers combine for about 5.5 kWh per load of laundry.

Each unit measures 861 mm wide by 1300.5 mm high, and sticks out 180 mm from the wall. Think of a 60-inch flat screen TV (which, by the way, uses about 0.1 kWh per hour) mounted vertically on your wall and that’s how much area it would occupy. It can be mounted indoors or out, to operate in the -20 C to 43 C temperature range.

The Powerwall will reportedly be built at Tesla’s new complex in Reno, Nevada, and will be ready to ship by summer 2015 with orders being accepted now. It has to be installed by a certified electrician.