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Solar Storage

On the day that Tesla announced they were building a new battery plant, we predicted that the batteries would be used not only for Tesla’s growing fleet of electric cars, but also to revolutionize energy storage. The prediction is now becoming reality as Tesla Motors recently announced the introduction of a super-efficient power storage system that finally addresses the challenge of how to tap into solar power when the sun isn’t shining. Dubbed the Powerwall, the system was derived from the rechargeable lithium-ion batteries originally designed for their Model S vehicles, and is affordable enough for homeowners, yet scalable for businesses and utilities as well.

The typical household demand for power is higher in the morning and evening, so for homes that are already equipped with solar panels, excess power generated during the day – when sunlight is most plentiful – is generally sold to the utility and purchased back when needed. But the higher demands that this places on power plants and the power losses inherent in the energy grid make this mismatch inefficient and costly. A system like Powerwall will help smooth out fluctuations in the grid and also provide energy security in the event of an outage.

Each battery block measures about 34 inches wide by 52 inches high by 7 inches deep (130cm x 86cm x 18cm) and weighs about 220 pounds (110kg). They operate at 92 percent efficiency with a peak output of 450 volts and 8.6 amps per battery to deliver peak power of 3.3kW (or 2kW continuously), and are compatible with both single-phase and three-phase utility grids. Up to nine packs can be connected together to handle higher energy needs.

The system will be installed by licensed technicians and linked up to the Internet to be managed by Tesla. Two models will be available with price tags of $3500 for a 10kW version and $3000 for a 7kW version. Production is scheduled to begin later this year.

For information: Tesla Motors; Web site:

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