The 550MW Desert Sunlight project has been completed in California, earning the distinction of being the world’s joint largest operational PV power plant.

Developed and built by US PV energy provider, First Solar, Desert Sunlight equals the record set by another of First Solar’s projects last year, the 550MW Topaz plant, also in California.

Although First Solar lists Desert Sunlight’s status as still “under construction” on its website, newly updated details published by the California Independent System Operator (CAISO) records the two elements of the project as having entered into commercial operation on 5 December 2014.

Desert Sunlight is located in Riverside County and is co-owned by NextEra Energy Resources, GE Energy Financial Services and Sumitomo Corporation of America.

Power from the plant will be sold under two separate power purchase agreements – 300MW to Pacific Gas & Electric over 25 years and 250MW to Southern California Edison (SCE) over 20 years.

But neither Topaz nor Desert Sunlight are expected to hold the ‘world’s largest’ tag for long; rival US firm SunPower is expected to complete its 579MW Solar Star project by the end of 2015.

According to CAISO, both elements of this project are now partially operational – 235.5MW of 270MW and 177MW of 310MW respectively.

Upon completion, Solar Star, previously known as Antelope Valley, will by owned by financier Warren Buffet’s energy investment vehicle, MidAmerican Energy. Power will be sold under PPA to SCE.