Illinois has restored power to its solar rebate program.

Until last summer, Illinois gave homeowners and businesses as much as $5,000 on a $10,000 solar system. Solar panels can supplement natural gas heat, which got more expensive last year.

But the program was temporarily halted as the state waited to learn more about how a new federal tax credit for solar energy would be structured for 2006. The state wanted the two programs to complement each other.

Now the state is starting its rebate program again, even though it doesn't have all the details about the federal credit, according to Hans Detweiler, deputy director of energy and recycling for the Illinois Department of Commerce and Economic Opportunity.

"We might have to hold our breath for a long time" to wait for publication of the new tax credit rules, Detweiler said. "We've decided to go ahead with the best available information."

The new Illinois rebate program will combine with a 30 percent federal tax credit under the energy bill passed last year.

The new Illinois rebate program provides a flat rebate of 30 percent for any system, up to a maximum rebate of $10,000. The old rebate program applied a 50 percent rebate on the first $10,000 of costs, and 25 percent on the next $20,000, for a maximum of $10,000.

With a $8,500 system, the new Illinois rebate would be $2,550, and then the federal tax credit would be $1,785, for a total savings of 51 percent.

The state has $500,000 available for this year's rebates, Detweiler said. It is also funding applications it received last year, under last year's program.

"Obviously, this is tremendous for the Illinois solar industry and Illinois citizens who want to use solar energy to reduce energy costs and pollution," Brandon Leavitt, president of Solar Service in Niles, said in a letter to leaders of the Illinois Solar Energy Association. All his customers have used the state rebates, and he said the absence of the rebate program hurt business.

"I'm going to get real busy," said Scott Crider, project manager for Solara Systems in Bristol.

A solar system that provides only hot water installs for between $8,000 to $10,000. A system that provides hot water and home heating is between $16,000 and $20,000.