SunPower Corp. (NASDAQ: SPWRA, SPWRB) recently invited media out to its joint production facility with Flextronics Corp. (Nasdaq: FLEX) in Milpitas, Calif., to witness firsthand how they’re able to use automation to assemble the world’s most efficient commercial photovoltaics in the world in a matter of hours.

The facility, which began commercial production earlier this year, went from an empty building in September to production in less than a year, said Alvin Mandin, a Flextronics program manager.

“On December 15, we actually built our first module here in this plant,” he said.

The companies dedicated the facility, in April 2011, with a module signed by DOE Secretary Steven Chu and California Gov. Jerry Brown (D), as well as the company’s head honchos and others. It has been producing modules on a commercial scale ever since.

The plant, with its singular production line, is capable of producing 75 megawatts annually. It was supported by the Department of Energy’s Solar Initiative.

“We won the largest grant under the Solar Initiative from the Department of Energy (DOE) about four years ago. We had about a half dozen major goals out of that project,” said Julie Blunden, Executive Vice President of Corporate Communications and Public Policy.

The company used the DOE funding to develop both a more efficient panel and lower-cost process for producing the panel, which resulted in the Milpitas plant, according to Blunden.

“And we did that. We ended up a higher efficiency panel, the E 20 came out of that research,” he said. “The equipment that was designed to be able to manufacture into Silicon Valley, a relatively high-cost labor center, by having a lot of it automated.”

The automation allowed SunPower to continue to reduce its manufacturing costs. The Milpitas plant still has some employees on the manufacturing floor, however.

“We specifically designed equipment that would allow us to make that commitment and did. And in fact we appreciated the outcome, we thought it was so successful that we bought the same equipment and sent it to Europe,” Blunden said.

By using U.S.-made manufacturing equipment, SunPower is increasing the value of DOE’s investment in SunPower and money the company spends in the U.S., supporting additional jobs in other industries, according to Blunden.

Click here for part two of the tour.