UPDATE 1-First Solar sells California project to NRG

* NRG to buy 21-megawatt solar project in Blythe

* Financial terms of deal not disclosed

LOS ANGELES Nov 23 (Reuters) - U.S. solar power leader First Solar Inc (FSLR.O) said on Monday that it was selling the first of its utility-scale solar power projects in California to national power plant operator NRG Energy Inc (NRG.N).

The companies did not disclose financial terms of the deal.

First Solar will operate the 21-megawatt solar power project for NRG Energy under a long-term contract, the company said in a statement.

Macquarie Securities analyst Kelly Dougherty said in a note to clients that the news "is an incremental positive" for First Solar and will likely add to the company's revenue for the fourth quarter.

Tempe, Arizona-based First Solar started building the project in September. The plant, about 200 miles east of Los Angeles in Blythe, California, is expected to be finished by the end of the year. Electricity from the plant will be sold to Southern California Edison, a unit of Edison International (EIX.N).

First Solar is one of the world's largest producers of photovoltaic cells, which turn sunlight into electricity. Its production costs are the lowest in the industry, although its thin-film cadmium telluride cells are not as efficient in capturing sunlight as more traditional silicon-based cells.

The sale follows another recent deal for First Solar. In October, the company sold a 20-megawatt solar power project in Ontario to Enbridge Inc (ENB.TO), Canada's largest oil pipeline company. [ID:nN02316492]

Princeton, New Jersey-based NRG has mostly fossil fuel-heavy power plants that generate enough electricity to serve 20 million U.S. households, but plans to add a range of renewable energy technologies. [ID:nN05526319]

The company owns three land-based wind farms in Texas and invested in solar thermal start-up eSolar earlier this year.

Shares of First Solar were up half a percent at $121.84 each in trading on Monday on the Nasdaq. (Reporting by Laura Isensee; Editing by Steve Orlofsky) ((laura.isensee@thomsonreuters.com; Los Angeles Bureau +213 380 2014))