"Electricians, plumbers, roofers -- we can put these people back to work," says Rhone A. Resch, president of the Solar Energy Industries Association, Washington-based trade group for the solar-electric industry.

Resch's group is teaming with IEEE, the electrical engineering society, to cosponsor this year's  PV America photo voltaic (that means solar electric) conference and trade show at the Pennsylvania Convention Center, 1101 Arch St. The groups say they'll bring 3,000 sun-powered business people and engineers here next Monday-Wednesday, June 8-10. On Tuesday afternoon 135 exhibits are open to the public, noon to 8 pm.

The brains of the solar business will be passing through Philadelphia: On Monday, besides Mayor Nutter and Gov. Rendell, U.S. Department of Energy solar czar JoAnn Milliken will talk to the paid attendees, followed by architects, engineers and solar pioneers from around the Northeast.

Tuesday, it'll be SunEdison founder Jigar Shah and other solar-business executives, and U.S. and state officials who'll review retraining programs for solar installation jobs. On Wednesday, it's ex-CIA director-turned-"energy independence" advocate James Woolsey along with solar investment analysts from Morgan Stanley and other Wall Street firms. University of Florida engineering scholar Tim Anderson will head the IEEE's Photovoltaic Specialists Conference, which will run concurrently with the trade show.

Philadelphia isn't sunny Phoenix. Why meet here? Because Northeastern states have taken the lead in subsidizing solar energy, says Resch. And those subsidies reach further thanks to federal tax breaks extended under Obama's budget.

Homeowners and small businesses can take a tax credit of up to 30% of the cost of a system from their federal income taxes. The Pennsylvania Sunshine Program offers a $3-per-watt state subsidy on top of that. So a $20,000 system costs just $5,000 to install, at least until the state grant money runs out, says Resch. Companies get similar breaks.