HelioSphera plans to spend $500 million to build a solar panel factory in Philadelphia. The city is offering to help offset the cost.

The private Greek company will start building the 500,000-square foot factory in the Navy Yard next year, and expects to start operating it in 2011, reported the Philadelphia Inquirer.

Philadelphia is offering $49 million in grants and loans to HelioSphera.

Funded by Plainfield Asset Management and Sciens Capital Management, HelioSphera only recently opened a 60-megawatt factory in Tripoli. That factory uses equipment from Oerlikon Solar in Switzerland to make solar panels that feature a layer of amorphous silicon and a layer of microcrystaline silicon.

HelioSphera expects to reach 30 megawatts of annual production next year and 60 megawatts in 2011, said Chris O'Brien, head of the North America marketing for Oerlikon Solar. 

HelioSphera hasn't said whether it plans to use Oerlikon's equipment for the Philadelphia factory as well. O'Brien, who spoke at the Thin Film Solar Summit in San Francisco Tuesday, declined to comment.

Clairvoyant Energy announced in September this year that it would build a 90-megawatt factory in Michigan and roll out solar panels with Oerlikon's equipment (see Oerlikon Solar Tools Coming to America). Clairvoyant, which is applying for a 30 percent federal manufacturing tax credit, expects to close the financing for the factory in 2010, O'Brien said.

A growing number of European and Asian solar companies are opening factories in the U.S. to take advantage of a growing market and the economic stimulus plan by the federal government to give billion of dollars in grants and loan guarantees to renewable energy equipment manufacturers and power plant developers.

Many states have required their utilities to increase their purchases of renewable electricity. These states are offering rebates for consumers and businesses to install solar energy systems.

Suntech Power of China is planning for a 30-megawatt factory in the Phoenix area. Sanyo of Japan recently opened a silicon ingot and wafer factory in Oregon.

German solar panel makers Solon, SolarWorld and Schott Solar all have recently opened factories in the U.S.

Photo of a HelioSphera production plant near Tripoli, Greece via HelioSphera.