Francisco DeVries was familiar with all the grand plans and high-flown talk about solarizing the world's power mix to fight global warming. Then he found himself staring at a problem that seems, somehow, to have repeatedly escaped the climate evangelists' attention.

DeVries is a confessed save-the-climate junkie, and his professional credentials include a stint as an appointee in the U.S. Department of Energy under President Clinton. More recently, though, he earned his paycheck as the chief of staff for Berkeley, Calif., Mayor Tom Bates. About two years ago, DeVries was charged with implementing an ambitious new measure to cut the city's greenhouse gas emissions 80 percent by 2050.

Despite California's reputation for all things green, less than 0.5 percent of homes in the state have photovoltaic systems. Berkeley's greenhouse gas-reduction program is, in large part, aimed at encouraging the city's homeowners to put solar panels on their roofs. Because DeVries was in charge of spearheading the initiative, he says, "I thought I should walk the walk: I thought I should get solar on my own house."

But when he knuckled down to the task, DeVries came face-to-face with the high cost of going green. "The bids came in, and I couldn't pull the trigger for all the same reasons that people everywhere aren't pulling the trigger," he says. "Which is, 'Oh my lord, that's a big check.'"

The average cost of a residential solar installation in California is around $30,000. That's not exactly the kind of money everyone has just lying around, and it confronts homeowners with the prospect of having to refinance their mortgage or open a home-equity line of credit to pay for an upgrade that, to a large extent, will serve the collective good. And, DeVries points out, if you install solar panels and then move — as the average California homeowner does every five to seven years — "that means you've just bought your next owner all this free electricity."

DeVries was hardly the first homeowner whose virtuous intentions were frustrated by the cold realities of credit. Many a person might have thrown their hands up in frustration, bought a couple of compact fluorescent light bulbs and salved the shreds of his public-spiritedness with a bottle of Chablis. But DeVries recognized his conundrum as a symptom of a bigger problem.

He was struck, in particular, that the money people spend on their monthly electric bill could instead be channeled into retrofitting their homes with solar. "The money's there. The money's there. People are paying it hand over fist, every month. But we as consumers aren't (doing solar installations)," he says. "At its root, there is a financing market failure for renewables and energy efficiency in people's homes. Everybody's talking about all the technology, but we have to solve the financing problem."

It is not, on its face, a particularly glamorous problem to take on. But two years later, DeVries seems to have devised a solution — one that, in spite of its decided wonkiness, Mayor Bates has taken to referring to as "Berkeley's most important contribution to fighting global warming."

DeVries has the slightly manic air you'd expect of a political chief of staff. He is a tall, rail-thin and slightly bookish person, with a to-do list that seems like it might benefit from a couple of extra hours in each day. By his own admission, DeVries' intellectual preoccupations tend to run "a mile wide and an inch deep."

At the time he was given responsibility for implementing Berkeley's greenhouse gas-reduction program, DeVries was actually trying to get out of public service. Bates had recently been elected to a second term as mayor, and DeVries had a 2-year-old son at home. "I had a really stressful job," he says. "I loved it, but I was a little burned out at that point."

For some reason, though, the clean-energy financing problem focused DeVries' energy. The problem wasn't actually money: If your monthly power bill is $130, as DeVries' is, you would make a total of $31,200 in payments over 20 years — about what it would cost to install a photovoltaic unit on your home. Put in those terms, going solar seems like a smart move. But, as DeVries discovered, plunking down cash on the barrelhead for a new solar system is a daunting proposition.

Mayor Bates recognized that if the city could provide financial assistance to homeowners, it would go a long way toward turning the city's carbon-emission goal into reality. But the financing, he says, was a sticky point: "It's hard to take your general fund money and put it into an untested idea."

As it happened, though, DeVries found himself involved in another matter of civic procedure that, he realized, offered a model for the problem that had come to preoccupy him. A Berkeley neighborhood had decided to put its utility poles and power lines underground. To pay for the project, the city created an underground utility district, a type of land-secured financing district that is a standard element of municipal bond finance.

The utility district would sell bonds to cover the upfront costs of the project. Homeowners in the project would then pay back the money through a tax assessment levied on their property — essentially an installment plan that would spread the repayment over 20 years, much like a recurring utility bill. The bonds would be made secure through a tax lien put on each participating property.

"We've been using (land-secured financing districts) for everything from parks to open space to streets to sewers to underground utility districts for 100 years," DeVries says. "And I thought, 'Well, geez: That mechanism might help solve my problem.'"

The utility-district kind of financing arrangement is especially attractive because a municipal bond carries relatively low interest, opening up a lower-cost option than would otherwise be available to homeowners. (Also, because the home itself serves as collateral, even homeowners with less-than-stellar credit are eligible.) But when it came to solar installation on people's houses, DeVries says, "nobody had ever tried to give individual property owners access to the municipal bond market before."

To open up access to that market, DeVries proposed creating a Sustainable Energy Financing District, into which property owners who wanted to install solar systems could annex themselves. That district could then issue bonds whose proceeds could finance the upfront costs of photovoltaic systems; participating homeowners could use the money they save on their utility bills to pay the tax assessment. That assessment stays with the property, so if a homeowner moves, the next resident picks up the repayment — and gets the solar power.

Under the program, a $30,000 system would carry a $245 per-month property tax. But, when offset with rebates from the local energy utility and state and federal tax credits (the federal credit alone, for 30 percent of the cost of the system, knocks the effective tax down to $172 per month), the price of going solar ends up being close to what it would cost to continue buying power from the grid.

The Berkeley City Council approved the Sustainable Energy Financing District in November 2007, and the idea immediately attracted interest from points far beyond Berkeley. In fact, two weeks before the city council greenlighted the program, the San Francisco Chronicle ran a front-page story about it. DeVries had the day off and was at home when the paper hit the streets, but within hours, "my cell phone went crazy. We received hundreds of calls — from property owners that wanted to do it, solar companies that wanted to be involved, other cities that wanted to learn how we were doing it."

Still, it wasn't clear who, exactly, would buy the bonds.

Last spring, DeVries finally left his job at the Berkeley mayor's office. He spent several months as a stay-at-home dad and moonlighted as a consultant for various clients on energy-related issues. But he found that once he'd started thinking about how to reduce the climate impact of the average home, he couldn't stop.

"I'm constantly cognizant of all the ways in which our homes are wasting energy," he says. DeVries is a confessed hot-tub aficionado, but "this whole thing has ruined hot tubs for me." Even spending time in homes and offices that still use incandescent light bulbs, rather than compact fluorescent lights, is, as he puts it, "like hearing nails on a chalkboard."

Berkeley, meanwhile, was struggling to get a bank to back its bonds. Several banks did express interest but, because they weren't sure how to incorporate the new type of bond into their portfolios, indicated that it could be awhile before they were ready to take the plunge. And worsening economic conditions didn't help.

"Banks have been traditionally very conservative, and of course they've gone through a horrible meltdown," Bates says. "It was the worst possible time to be talking to them about a new idea."