Utility PG&E, SolarReserve sign power contract

* SolarReserve to sell power from 150 MW project to PG&E

* Privately held company uses solar thermal technology

* Shares of PG&E Corp close down 0.6 pct at $44.81

LOS ANGELES, Dec 22 (Reuters) - California utility PG&E (PCG.N) will buy power from a 150 megawatt solar power plant built by privately held SolarReserve under a long-term contract, the companies announced on Tuesday.

California has a target to obtain a third of its electricity from renewable resources by 2020, but one issue facing the clean power sector is how to store energy for times when the sun does not shine or wind does not blow.

SolarReserve's project uses mirrors to focus sunlight to heat molten salt, which in turn heats water for a steam generator to produce electricity. The molten salt technology also can store the energy when sunlight is not available.

State regulators must approve the power deal between PG&E and SolarReserve.

The project is expected to be completed in 2013 and to generate enough electricity for some 60,000 homes, the utility said.

The Santa Monica, California-based SolarReserve also landed on Tuesday a 25-year power purchase agreement with NV Energy (NVE.N) for the energy generated by a 100 MW solar project that the renewable player is developing in Nevada.

Privately held SolarReserve has a license to use the molten salt solar power technology developed by United Technologies Corp (UTX.N).

Shares of PG&E Corp closed down 0.6 percent at $44.81 on Tuesday on the New York Stock Exchange. (Reporting by Laura Isensee; Editing by Gary Hill)