The Imperial Solar Energy Center South facility, one of the largest commercially financed solar plants in the U.S., commenced commercial operations on Nov. 1 near El Centro in California, just north of the Mexican border.

The 130 MW project, which was developed by Tenaska Solar Ventures, began construction in December 2011 and consists of nearly 2 million solar panels. It was built on a 946-acre site in southern Imperial County. The plant sells its power to San Diego Gas & Electric (SDG&E) under a 25-year power purchase agreement. Electricity from the plant will flow to Southern California through the new 117-mile, 500-kv Sunrise Powerlink transmission line, which was built specifically to spur development of renewable energy in the Imperial Valley. Imperial South was the first large-scale solar project to connect to the line.

Engineering, procurement, and construction were provided by a subsidiary of First Solar, which is also operating the plant under a contract with Tenaska. Prudential Financial purchased a minority interest in the project last month.

In addition to Imperial South, SDG&E has contracted with Tenaska for the power produced at a second Imperial Valley solar project, Tenaska Imperial Solar Energy Center West, also near El Centro. It will produce up to 150 MW of electricity under a 25-year power purchase agreement. Construction is due to start next year, with commercial operation scheduled for 2015.

The projects will help SDG&E meet its obligations under the California renewable portfolio standard to obtain at least 33% of its power from renewable sources by 2020. Currently, SDG&E’s portfolio comprises about 23% renewables.

Thomas W. Overton, JD, gas technology editor (@thomas_overton, @POWERmagazine)