Elon Musk introduced lithium-ion battery named Powerwall – a wall-mounted energy storage unit that can hold 10 kilowatt hours of electric energy, and deliver it at an average of 2 kilowatts, all for US$3,500. This halves the normal cost of a backup battery for a solar or wind installation making it both easier to go off grid or create a distributed system within the utility grid.
This has implications for small community owned utilities and microgrids since it appears to bring the cost comparable (on a per KW basis) to fossil fuels plants when coupled with renewable energy generation.
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