Less than a third of the way into 2009, Long Island residents have already snapped up more than 50 percent of Long Island Power Authority‘s generous $12.5 million in rebates for customers installing solar energy systems. A similar program in Pennsylvania, launched today, will start taking applications in two weeks.

Newsweek attributes the LIPA program’s popularity this year to “hefty new federal tax credits and ambitions for cheaper, cleaner energy.”

Whatever is fueling the rush to solar, it’s raising concerns that the LIPA will reduce or suspend the program if the budget runs out. But the utility said last week that it is seeking additional funding sources and will adjust the program to keep it flush, if needed.

None of this will come as a surprise to solar advocates in New Jersey who saw their state rocket up the charts to Number Two nationally in solar installations (only behind California but ahead of traditional sun states like Arizona and Florida) after the state Board of Public Utilities (BPU) in 2001 rolled out an enticing program of grants to homeowners, businesses and institutions.

Those who got in early saw rebates that cut their installation costs from 30 to 60 percent.

The program proved so successful that it ran out of money about the same time that the state budget started to tank (a dismal process continuing today).

Seeking a replacement program, the BPU subsequently developed a system based on trading renewable energy credits but experts say it’s still too early to tell how successful it will be.

The state’s largest utility, PSEG also has chipped in with a solar loan program available to its customers.

In Pennsylvania, just today, the Commonwealth Financing Authority voted to borrow $30 million to get its Sunshine Program under way. Subsequent financing should bring that program’s total to $100 million, reports to the Philadelphia Inquirer.

Enacted in July, as part of Gov. Rendell’s $650 million Alternative Energy Funding Act, the program will provide rebates to homeowners and small businesses to partially cover the cost of installing a solar-power system. Pennsylvania’ DEP, which will be running this program, said applications should be available within two weeks

With the Obama administration promoting solar and wind and other ‘renewables’ as the way to to reduce both greenhouse gases and dependence on foreign oil suppliers, public interest is only likely to grow, and programs like LIPA’s, PSEG’s, New Jersey’s and Pennsylvania’s may be oversubscribed in record time.

The takeaway?

Remember George W. Bush’s lesson on global warming and alternative energy: He who hesitates lost.