Peter Rive says SolarCity is putting the solar-battery backup system in 100 residential and commercial pilot projects.

FORBES: SolarCity IPO Roadshow: We Sign Up A New Customer Every Five Minutes

The microgrid comprises eight 100-kW grid-tied inverters, the rooftop PV array, the lead-acid battery pack, backup diesel generators, and a Web-based monitoring and control system.

FORBES: Solar-Powered Microgrid Slashes Alcatraz Island's Dependence On Fossil Fuels

After some fumbling in the dark I ripped out the failing 9-volt backup battery and it went dead.

FORBES: Hurricane Irene Sparks An Electronic Counterattack

It can also be connected to an external 5-volt Lithium-ion polymer battery for backup power, enabling use in areas where electricity can be inconsistent.

ENGADGET: Marvell and Stanford create SMILE Plug cloud computer, SMILE Consortium to get companies and devs to build a better education system

Solar panels will supply the electricity at Supercharger stations, with a 500-kilowatt-hour supersize version of its car battery as backup storage.

FORBES: How Two Billionaires Are Supercharging The Electric Car To Upend Big Oil

The two 5W-powered USB ports allow users to connect even two bus-powered external hard drives and also function as a backup battery for two iPads.

ENGADGET: Hyper debuts iUSBport mini, 2 and HD cloud storage and streaming devices (hands-on)