Commercial electricity production began yesterday at what Sempra Energy calls the largest solar plant of its kind in North America, a unit that will power homes and businesses in Northern California for at least the next 20 years.

The 10-megawatt plant owned by Sempra subsidiary Sempra Generation covers 80 acres of desert in Boulder City, about 40 miles south of Las Vegas. It's next to a 480-megawatt gas-fired plant, also owned by Sempra Generation.


The plant was built in six months and is the first of many, said Michael Allman, Sempra Generation's chief executive.
"Our goal is to be the first company to own and operate 500 megawatts of solar power in the world," he said. "We expect that most of it will be in the Southwest."

San Diego-based Sempra said it has sold the plant's output until 2029 to San Francisco's Pacific Gas & Electric, which has about 15 million customers.

When running at peak capacity, the solar plant will power about 6,400 customers, Sempra said. Output of solar plants varies with the time of day and how brightly the sun is shining.

Overall, the 23.2 gigawatt-hours the plant is expected to generate a year will power about 3,400 customers, PG&E said.

The plant uses thin-film technology, which produces less electricity per panel than traditional silicon-based photovoltaic power but is cheaper to build.

Photovoltaic power converts light directly into electricity. Other solar technologies rely on heat from the sun to power generators.