There's no question that production home builders have warmed to solar power and HVAC systems. It makes sense to offer such state-of-the-art, energy-efficient systems in an environment in which builders are forced to compete with cheap foreclosures, short sales, and new homes from competing builders that are still burning oil and gas for heat and paying the electric company for everything else.

Still, with all the flapdoodle about global warming, climate change, or whatever they're calling it this month (science is one thing, politics quite another), it might serve one well to remember that photovoltaic technology is not yet cost-competitive with carbon. That's true even taking into account generous government incentives, which are slowly being reduced. And it won't be cost-competitive for some time to come.

That doesn't mean it's not worth the added expense. But until that expense comes down, solar for power generation and HVAC (other than preliminary water heating) won't be showing up in every new home built—unless, of course, the government forces the issue, which looks far less likely than it did a year ago.

With all this in mind, we got on the horn with Gordon Handelsman, co-founder and chief marketing officer of PVT Solar in Berkeley, Calif. PVT makes the Echo™ solar system, which, in our experience, is the most efficient photovoltaic system on the market (see the April 2010 Tech Spec column). It is presently offered by Joseph Carl Homes in the Estrella master planned community in Goodyear, Ariz., and in six Meritage Homes communities in Arizona. PVT in September completed a second round of venture financing and named Vikas Desai, previously VP/GM of SunPower Corp.'s residential and light commercial business unit, to the post of CEO. We asked Handelsman the big question: When, then?

Understandably, it was a question he couldn't answer, directly at least. No one can. But Handelsman explained what needs to happen before solar is installed on every new-home roof in America. And that would be increases in energy production efficiency coupled with lower manufacturing costs resulting in the peak cost per watt produced falling to the $1 to $1.50 range, depending on location. That cost was approximately $10 four years ago and has since fallen to $8 for smaller PV systems, $6 to $7 for larger-scale installations. An infrastructure of solar specialty companies and utility experts is also needed: Currently, most electricians don't know solar from rough plumbing.

“Solar is getting more and more cost-effective,” Handelsman says. “But in most places in [government or utility], incentive is necessary to catalyze the market.” Meantime, consumers, he says, “want solar to save them money.”

SUN SPOT: Meritage Homes' Lyon's Gate, in Gilbert, Ariz., is one of the few communities currently outfitted with PVT Solar's Echo™ solar system.

The Echo solar system is about as efficient as it gets. Generic PV panels, which are basically what the system uses, are about 15 percent efficient (in other words, they convert approximately 15 percent of sunlight into usable energy). Getting that 15 percent to 16 percent is quite difficult, Handelsman says, and will likely take years rather than months. On the thermal side, however, the Echo is 50 percent efficient, largely because it uses the heat generated by the sun on the panels for HVAC and hot water but also because it is controlled by a sophisticated computer. Handelsman's goal is to get to 60 percent efficiency within the next several years, and when PV efficiency hits 20 percent, to take the system up to 65 percent.

As efficiency gains are made, the cost per watt of energy produced falls.

“If today is about delivering twice as much energy as basic PV, then five years from now the goal is to deliver three times as much energy,” says Handelsman.

Which means, for PVT at least, the future of solar is bright, if still a little distant.