To provide more solar capacity per customer than any utility in the United States - using molten salt to store heat and continue generating electricity for as long as six hours after the sun sets.

The premium is worth it because coal and natural-gas prices are unpredictable, and emissions from those plants likely someday will be taxed for their contributions to global climate change: That makes predictable solar prices attractive.

Abengoa Solar Inc., a Spanish technology company that has several smaller solar-thermal projects in Spain, North Africa and the United States, will build and run the Solana Generating Station.

Its current U.S. installations use mirrors to concentrate sunlight and heat water for prisons in Arizona, Colorado and California, a military base in Texas, and one scheduled to come online this year for a California Frito-Lay chip factory.