Last year, two photovoltaic power plants crossed the 100 megawatt threshold—neither were on American soil, but that’s likely to change in 2012 and certainly in 2013. One of the projects likely to cross that threshold first is Sempra Generation’s Mesquite Solar 1 project, a 150-megawatt project in Arizona. After just six months of construction the site is producing 42 megawatts of power for Pacific Gas and Electric (PG&E).

Still, the company downplays the significance of reaching such a milestone.

“Who’s going to reach 100 megawatts first? Who knows; it’s less important than the fact that we’re growing [quickly],” said Sempra spokesperson Scott Crider. “We have 300 megawatts of solar under construction simultaneously. It just shows how strong the industry actually is.”

Projects by other companies may also cross the 100 megawatt barrier in 2012, including some 200+ megawatt projects being developed by NRG, SunPower and First Solar.

The project, which is using Suntech modules, is moving forward at a much more rapid pace than utility-scale power plants that use other technologies, like fossil fuel, nuclear and even wind-power plants.

“That’s one of the advantages of photovoltaics. We can start generating before the project reaches completion, unlike wind solar thermal or fossil fuel power plants,” Crider said. “We only broke ground on Mesquite Solar in July or late June. To get 42 megawatts operating by late December shows how quick we can get these projects up and running.”

Each PV project is becoming easier for Sempra as well, according to Crider.

“I think what’s made the [newer] developments easier is experience overall,” he said. “We’re now on our fourth, and with each development we’ve learned lessons on each project.”

He also attributed the speed of the installation to working with the panel manufacturers it’s developed projects with, Suntech and First Solar and the construction contractor Zachry.

“At all levels, as the industry matures and as these projects grow, everyone ‘s getting better,” he said.

While this two-phase project will fulfill a 20-year power-purchase agreement with PG&E, the Mesquite site could be expanded out to 700 megawatts.

“We’re continuing to market the remaining capacity to utilities throughout the Southwest. If a utility needs 50 megawatts, we can knock that out pretty quickly,” Crider said.

The site, which is on low-quality habitat land, is already graded and immediately adjacent to high voltage lines, and other power plants.

Pictured: Sempra’s Copper Mountain solar park.