The Interior Department's secretary "opened up a new chapter on renewable energy" on Tuesday when he signed permits for two solar projects in California.

The precedent-setting projects - in Imperial and San Bernardino counties - mark the first solar projects on federal land. The 6,360-acre Imperial County project, to be overseen by San Diego Gas & Electric, will be about 95 miles east of San Diego. Chevron Energy Solutions will oversee the Lucerne Valley project, slated to encompass 422 acres, northeast of San Bernardino.

"We have opened up a new chapter on renewable energy on our public lands in America," Interior Secretary Ken Salazar said in a conference call. He said President Obama asked him to upgrade efforts to produce energy on federal land.

Hundreds of thousands of homes stand to benefit from the projects, but the projects likely will require more than a year to be built and begin generating.

The 45-megawatt Lucerne Valley project will use photovoltaic solar panels to supply electricity to as many as 33,750 homes.The solar-thermal project in Imperial Valley would be one of the largest solar projects in the world, supplying up to 709 megawatts of electricity to power as many as 531,750 homes.