Yesterday (July 17) Agua Calienete, a solar photovoltaic farm being built in Yuma, County Ariz., became the world’s largest operational photovoltaic power plant when it reached 200 megawatts (MWs) of AC installed and operational power. And it’s not completed yet. The project is slated for completion in 2014, at which time it will provide 290 megawatts of AC power to Pacific Gas & Electric (PG&E).

There are two other projects that have touched the 200 MW mark, the 220 megawatt Golmud Solar Park in China which was completed in October 2011 and the 214 MW Charanka Solar Park in India, which was completed in April 2012. However, both of those PV farms are measured in terms of DC power. However, the conversion from AC to DC power is not equal. For instance, upon completion the 290 MW AC Agua Caliente plant would also produce 348 MW DC. “We’re pretty excited to have reached this milestone,” said NRG spokesperson Lori Neuman. She added that while it's nice to lay claim to the title of world’s largest photovoltaic array, she knows it will be a short-lived title, after all larger plants are underway, including the 500 MW AC Topaz project First Solar is developing for MidAmerican.

First Solar Spokesperson Alan Bernheimer said it might hold onto the title for a little while, however. “There are two [First Solar] projects with higher capacities, 550 MW each: Topaz and Desert Sunlight. But neither is moving along at the installation velocity that Agua has had. I think Agua will be the biggest for a while.”

The project, being built by First Solar, Inc., is jointly owned by NRG and MidAmerican Solar, a subsidiary of Warren Buffet-controlled MidAmerican Energy Holdings Co. To help reduce the costs of financing for the project the Department of Energy awarded the project a loan guarantee.

“Construction has been continuous for the project. We just announced the latest phase. They have had a pretty hard schedule to follow,” Neuman said. The pace of construction has been pretty fast and furious at the site. As of the end of February First Solar had only completed 30 MWs of the project.

At that pace, the rest of it could be online by the end of the year but that won’t happen, according to Bernheimer. He explained that the project’s 25-year power purchase agreement stipulates that the rest of the power comes on in stages until it reaches the planned capacity of 290 AC MWs by 2014.