In Japan, electronics maker Sanyo is selling all-electric homes that have solar panels and lithium-ion batteries to provide backup power.
Sanyo Homes Co., a subsidiary of Sanyo, is selling pre-fabricated homes with 3.78 kilowatt solar power system, along with a 1.57 kilowatt battery system to provide power at night or on cloudy and rainy days, according to a press release.
The homes will have 10 LED light fixtures that use direct-current power, to minimize power loss in converting to AC power. The home's heat-pump water heater will be powered by solar, too.
The houses, which are 132 square meters, will cost about $350,000. In Japan, the houses will qualify for a $28,000 subsidy.
In the U.S., the Z6 concept house was in 2007 cited by American Institute of Architects as a top-ten example of sustainable architecture and green design solutions.
The Z6 house has a 2.4KW PV array above the roof. This array acts as a shade canopy at the roof stair access. The PV array was designed to provide 60-75 percent of the home's energy usage.