NRG Energy and SunPower are teaming up to build one of the biggest solar plants in the world and one of the only plants of its scale using photovoltaic solar technology.

The California Valley Solar Ranch in San Luis Obispo County is expected to produce 250 megawatts of power using SunPower’s signature ground-mounted sun tracking technology.

The 250-megawatt solar plant will be one of the largest in the world. Most of the other large-scale projects, like the project going up near Blythe, Calif., and another in Abu Dhabi, United Arab Emirates, use solar trough technology.

NRG has several other large utility-scale projects in the works around the country as well, spokesman Dave Knox said. One of the company’s largest solar projects, the Ivanpah plant, which will generate 392 megawatts of power north of Needles, Calif., uses solar thermal technology.

“NRG is focused on having a diversified solar portfolio,” Knox said.

NRG decided to partner with SunPower, Knox said, because the company has a solid reputation as the largest photovoltaic solar manufacturer in the United States and one of the world’s leading installers of utility-scale projects.

“Each technology has its own advantages,” Knox said. “The nice thing about PV is that it’s a proven technology.”

SunPower has over 400 megawatts of similar ground-mounted sun tracking systems installed and generating power around the world right now, SunPower spokeswoman Ingrid Ekstrom said.

The company’s sun-tracking system, allows the panels to follow the sun through the sky, increasing efficiency by up to 25 percent, Ekstrom said.

“The real advantage of our technology, of PV, is that it’s easy and fast to install,” Ekstrom said. “It’s also flexible, so you can reconfigure the panels after they’ve been installed.”

The California Valley Solar Ranch project has been in the works for two years and is expected to begin at the start of 2011. It is expected to generate enough electricity to power 100,000 homes, moving California closer to its goal of getting a third of its energy from renewable sources by 2020, according to a press release.

NRG will own and finance the project while SunPower will develop, design, build, operate and maintain the facility, according to the press release.

The Solar Ranch also signed a 25-year contract to sell the 250 megawatts of power it generates to Pacific Gas & Electric.

Image courtesy of SunPower.