Opponents are turning up the heat on a bill that would require all new single-family homes in Hawai'i to have solar water heating systems, with less than a week before Gov. Linda Lingle has to decide if she will veto it.

Legislators last month passed Senate Bill 644, which would require solar water heating in new houses beginning in 2010. Exceptions would be allowed under certain conditions.

A representative for Lingle's office said the governor is reviewing the bill and is taking into consideration public comments. Lingle has until Monday to notify the Legislature of an intent to veto.

Officials say Hawai'i already has one of the nation's highest rates of solar power use, with just over one in four homes having a rooftop solar water heating system.

Supporters of the bill said it would be a critical move in reducing Hawai'i's use of fossil fuels and could bring significant savings as oil prices continue to rise.

Despite the prospects of new jobs and cost savings, some in the solar industry have strong reservations against the bill.

"We all have the same objective of maximum solar uptake, but we don't feel mandates are the right way to get there," Ron Richmond, a manager for Inter-Island Solar Supply, said yesterday at a meeting of The Advertiser's editorial board.

Richmond said he is concerned the bill will increase home costs and strip homeowners of the right to choose how to power their homes. A typical home solar system costs $5,500 to install, and is expected to cost $6,000 in 2010, he said.

Rick Reed, president of the Hawai'i Solar Energy Association, echoed those fears.

"I'm concerned about this trend because I don't know where it stops," Reed said. If the state were to mandate solar water heaters, "why not mandate the right fluorescent light, Energy Star appliances or proper landscaping?" he said at the editorial board.

Supporters of the solar mandate said it will benefit Hawai'i. "When the public benefits rise to a level as significant as those that will come from a solar hot water bill, then mandates make sense," said Sen. Gary Hooser, D-7th (Kaua'i, Ni'ihau), who introduced the bill.

"We are shocked" that members of the solar industry are opposing this bill, said Jeff Mikulina, director of the Sierra Club Hawai'i Chapter. "The new mandate would create a lot of new jobs in the solar industry."