The biggest solar power plant in the country will be built in West Sacramento, after a Spanish solar development company chose the city for its U.S. headquarters, the company confirmed Monday.

West Sacramento and its port, where the plant will be located, beat Oakland to grab the new national headquarters of Otras Producciones de Energia Fotovoltaico. The company develops solar power plants and manufactures the tracking systems solar panels are mounted on.

The company's subsidiary, OPDE U.S. Corp., officially began operating on March 1 in a roughly 70,000-square-foot building at 1430 Enterprise Blvd. in West Sacramento. But OPDE isn't coming here alone. It's bringing along two more subsidiaries and two suppliers.

Over the weekend, OPDE began assembling dual-axis trackers that will each hold 56 solar panels for another company's Madera plant. At about 1,000 square feet, the trackers are each the size of a three-car garage.

OPDE's 20-megawatt AC power plant, boasting 26,880 solar panels on single-axis trackers, will be the largest in the United States. The first half is expected to go online this year, and the other half by June 2011, said Greg Brehm, director of distributed renewable energy resources for OPDE U.S. The power plant was initially reported as 24 megawatts.

"This will still be the largest," he said. "We're very happy to have opened here as one of the green and sustainable companies in our community."

The next-largest is a 14-megawatt plant at Nellis Air Force Base in Nevada. Another company has talked about building a 20-megawatt plant in Florida, but that doesn't appear to be going anywhere, Brehm said.

The company, which signed a lease for the building in October, is currently undergoing the process to get conditional use permits for the solar plant from the city and county, said Mike Luken, (economic development and port manager for West Sacramento.

OPDE searched Northern California enterprise zones from Oakland to Roseville to find a site for the headquarters of its fabrication facility, Luken said. The company had a small sales office in Oakland already.

Several factors helped with the choice to move to West Sacramento. One of the biggest was West Sacramento's "minimal" business tax, which will save the company at least several million dollars a year, Brehm said.

"It's a very skinny margin on these projects," he said. "You have to squeeze out every penny to make these projects make sense."

OPDE also found a 160-acre site that was available next to the port's deep-water channel. That site could host a photovoltaic plant in part because the Delta breeze coming up the channel will help cool solar panels by two to three degrees on the hottest days. Oakland, which also has a port, was the next biggest competitor.

A large open space on the site's west side will also help. The site is protected from flooding because it sits 30 to 40 feet above surrounding terrain.

"Panels lose productivity, so you want to have a fairly cool site," said Brehm, adding that panels lose half a degree of productivity for every degree the temperature gets over 70.

The city of West Sacramento helped them find the right building for a manufacturing headquarters nearby. The city also offered trading incentives. Imported components that will be used in renewable energy equipment won't be subject to taxes or duties, Brehm said.

"We've just presented to them a very business-friendly climate here in West Sacramento," Luken said.

About 12 people, including three from Spain and others from Oakland, are already working at the manufacturing facility. OPDE will hire 25 to 50 headquarters staff and 50 to 70 for assembly jobs. Another 250 or so will be hired to construct the solar plant and possibly others in this country.

The move by OPDE, its subsidiaries Meca solar and Proinso, and suppliers will create a center of operations for the North American market here, said Bob Burris, deputy director of the Sacramento Area Commerce and Trade Organization.

OPDE will now be the country's only manufacturer of this dual-axis tracking system, which tracks the sun across the sky, he said.

Two other European companies that already do business with OPDE also have national headquarters in the region. SMA Solar Technology of Germany, which makes inverters for solar modules, is in Rocklin. Optisolar, also from Germany, set up in Sacramento a year ago to make solar panel films.

OPDE's move is part of "an interesting network that's developing in the region," Burris said. "For all these companies to locate here, that says a lot about the reputation of our area in the solar industry."

Photos by: OPDE, Suzanne Hurt and Port of West Sacramento. Suzanne Hurt is a staff reporter covering business and development for The Sacramento Press.