Michigan Gov. Jennifer Granholm announced today that Suniva from Norcross, Ga., would invest $250 million to build a silicon solar cell factory in the Saginow County's Thomas Township.

Michigan's Economic Growth Authority has approved a tax credit valued at $15 million over a five-year period for Suniva to build the factory here.

The company already has a 96-megawatt factory in Georgia. The company began producing solar cells about a year ago.

Suniva would get the tax break only if it's able to line up a federal loan guarantee, reported Saginaw News. The report said Suniva plans to build the 400-megawatt factory in phases, starting with 2010.

I've put in a call to Suniva to find out more about the factory project.

Michigan is shaping up to be a magnet for solar companies. It recently attracted Santa Barbara, Calif.-based Clairvoyant Energy to set up a solar panel factory in a closed Ford plant in Wixom. Michigan is offering $25 million in tax credits over two years to Clairvoyant, which plans to buy factory equipment from Oerlikon Solar in Switzerland.

Clairvoyant is teaming up with battery maker Xtreme Power in Kyle, Texas, to redevelop the site. Xtreme is set to get a tax credit of $100 million over four years, according to Granholm's office. Clairvoyant plans to invest $857 million while Xtreme would pony up $475 million to buy and develop the 320-acre site, the governor said in a statement.

The two companies also need to line up federal loan guarantees to develop their plans.

Lining up state incentives doesn't necessary help companies get financial aid from the federal government. Boston-Power, for example, lined up incentives from its home state of Massachusetts but didn't get a federal grant to build a lithium-ion battery factory.

Although Granholm has been aggressive in attracting manufacturers from across the country and even from other nations, the results have been mixed. A story in The Washington Post today said the state has lost far more jobs during her tenure so far than it has gained. Michigan has the country's highest unemployment rate, at 15.2 percent.