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.

Read more at Tesla