Toyota has developed a vehicle to home (V2H) system to share power between between electric vehicles and homes, and will test it at the end of this year. The system shares power from home to vehicle and vice versa, and will be tested in approximately 10 Japanese households. These tests will use Prius plug-in hybrids — which can power an average Japanese household for about four days on a fully charged battery and a single tank of gasoline according to JCN Network — and can be useful in emergencies or when electricity rates are high. The V2H system is part of the Toyota City Low-Carbon Verification Project, which aims to use "low-carbon electricity" from solar generators or low-cost electricity stored during night hours to power both households and electric cars. Recent electricity shortages in Japan and increased interest in renewable energy sources drive the Toyota City Project, which began in April 2010.