Concentrating solar technology is the new solar technology to be implemented in California, which hopes to generate 33 percent of their electricity from renewable sources by 2020. In concentrated solar technology, reflective mirrors are used to concentrate light onto a liquid to make steam. This steam then converts energy into electricity with the help of conventional turbines.

Southern California Edison is working with a company named BrightSource to erect “power towers,” which consist of moving mirrors to concentrate light onto a tower to make steam to produce 100-megawatts of power in Ivanpah, California. By 2013 they are projecting to light up 65,000 homes by supplying 286,000 megawatt-hours of electricity per year.

Pacific Gas and Electric is one of the biggest utilities in the U.S. and has a good history as a progressive purchaser of solar energy from third parties.

Today, however, at the Clean-tech Investor Summit, PG&E CEO Peter Darbee stated that they now intend to build their own solar energy installations.

Without getting into the specifics of the size of the solar energy farms he did allow that they would be similar to Southern California Edison’s program, which is budgeted at $875 million over the course of five years, and will involve the placement of 65 million square feet of solar panels on commercial rooftops.

These are the sort of initiatives that will be necessary to meet California’s mandate that by 2020 utilities generate 33% of their electricity from renewable sources. A mandate that is being catalyzed by the 30% tax credit companies receive for renewable energy projects.