UPDATE 1-Germany's SolarWorld to build solar factory in US

(Adds details, analyst comment, share price)

FRANKFURT, March 1 (Reuters) - German solar cell maker SolarWorld (SWVG.DE) said on Thursday it had bought a solar factory in the United States for 30 million euros ($40 million).

SolarWorld said it would further develop the Oregon site for silicon wafer and cell production, investing 300 million euros ($400 million) and expecting to reach a capacity of 500 megawatts by 2009.

The state of Oregon will make 25-50 percent of the investments through its anti-global-warming program, Chief Executive Frank Asbeck told Reuters.

SolarWorld bought the factory for 30 million euros from the Japanese Komatsu Group (6301.T), which had invested about 600 million euros in the site, but had never started production there due to weak demand in the chip industry.

Production at the site, which is near one of chip maker Intel's (INTC.O) factories, will start in the middle of this year, SolarWorld said.

"This move strengthens SolarWorld's position relative to its rivals. The plant is located in the most promising market and should generate economies of scale," Peter Wirtz, analyst at WestLB, wrote in a research note.

Including an expansion of silicon wafer production at its plant in eastern Germany to 500 megawatts, SolarWorld's capacity is expected to exceed 1 gigawatt by 2010, it said.

The firm had bought Shell Group's (RDSa.L) loss-making silicon solar operations for an undisclosed sum in February last year, making it one of the largest players in the U.S. solar energy market.

SolarWorld shares closed up 3.4 percent at 56.42 euros after rising as much as 9.2 percent earlier. (Additional reporting by Anneli Palmen)