Going solar? Seven sites map your plans

Homeowners who dream of their electric meter spinning backward may seek solar panels to slash bills and carbon emissions. But where to start?

Before you call a contractor, these sites can assist with the early steps, like summing up what you could spend or save in your neighborhood.

The pioneering San Francisco Solar Map offers personalized evaluations.

San Francisco Solar Map

The San Francisco Solar Map helps locals lay their solar plans. A Google map pegs projects already up and running. Type in your address for estimates of installation fees and long-term utility bill savings and to find installers listed by the California Energy Commission.

Fog City's municipal rebates, added to state and federal incentives, probably make it the least expensive place for homeowners and businesses to add photovoltaics. Residents taking advantage of all discounts might drop the hardware and construction costs from, say, $25,000 to $7,000. The Web site supports Mayor Gavin Newsom's goal of 10,000 solar rooftops by 2012. It's the work of the San Francisco Department of the Environment and CH2M Hill, a consulting firm.

Solar Boston's map displays the solar potential for an address or even a city block.

Solar Boston

Mayor Thomas Menino's Solar Boston project aims to ramp up installations from half a megawatt to 25 megawatts by 2015. Its Flash-based map tracks solar, wind, biomass, and hydropower sources around town. You can enter an address, select a building, or even highlight an area on the map, to view the potential in dollars and kilowatts for topping roofs with photovoltaics.

Both San Francisco and Boston belong to the Department of Energy's Solar America Cities initiative to fast-track the spread of solar power. The two cities' maps are early, model tools. I'd also like to see peer comments and Yelp-like ratings of services and products. And I'd expect such services to help consumers share tips and report about the longest-lasting equipment as the solar sector matures. For instance, I found more than three dozen installers within 30 miles of my San Francisco apartment, but I'd have to do research elsewhere to decide whom to trust.

How do solar panels affect a home's resale value? Somebody should integrate solar maps with real estate listings, in the style of Trulia or Zillow.

Cooler Planet's maps include regional incentives around the country to estimate solar costs and savings.

Cooler Planet

Cooler Planet's solar maps cover territory from coast to coast. Google Maps mashups from the Seattle environmental marketing firm chart solar rebates, existing installations, costs and savings, and installers around the country. We learned that photovoltaic panels atop a three-flat in Chicago, where only federal incentives are available, could halve the $300 monthly electric bill and pay for themselves after 28 years.

Cooler Planet also rates solar incentives by state, painting Louisiana and Oregon as surprisingly bright. Another map tracks the growth of solar in California since 1999.

Choose your building, and Sungevity will create an estimate of its solar potential.

Sungevity

Sungevity asks you to pick your San Francisco Bay-area building on a map and describe the roofing material in exchange for an e-mail quote of solar costs. Technology from Microsoft Virtual Earth enables the company to take into account the angle of a roof, which affects the light available to solar panels throughout the day. That could lead to fewer measurements in person, saving time and money.

RoofRay relies on your rooftop drawing to figure a slanted roof into its cost estimates.

RoofRay

RoofRay also looks at the slant of a roof, although with less precision than Sungevity. Locate your building on a Google Map, draw an outline of the roof, and estimate the pitch. RoofRay asks for your average monthly electric bill, then spells out a detailed financial analysis. The site requires registration and asks for snail mail and e-mail addresses with a phone number. To put an interactive RoofRay widget on a blog, code is available for a quick cut-and-paste.

This rapidly-growing grassroots effort aims to get more than One Block off the Grid.

1BOG

San Franciscans Sylvia Ventura and Dan Barahona launched One Block Off the Grid in June to help bring cheaper solar power to the people. The effort organizes homeowners to bargain together with businesses to drive down the costs of installation. Several dozen people who joined the first campaign enjoyed savings of up to 40 percent, according to 1BOG.

Last week, the couple sold their nonprofit to Virgance, a social media and activism start-up. The 1,153-member solar effort has spread to 20 cities. It's even taking a stab at solar agreements between tenants and landlords. Neighborhood Solar is a similar grassroots purchasing program in Denver, where 1BOG is establishing a toehold.

Wattbot's recommendations of cleaner energy technologies are set to launch in January.

Wattbot

Wattbot, which remains in preview testing, promises custom evaluations in January to help households save money and carbon emissions. Share your address, and it will detail potential energy-efficiency and renewable technologies for your address. More than a solar-referral tool, it will also evaluate the financial impact of modest tweaks, like swapping old lightbulbs with compact fluorescents. You'll be able to contact service providers, take notes on projects, and connect with fellow users.

For now, there's just a simple U.S. heat map of renewable energy adoption. Wattbot is also building a service for clean-tech companies to track sales leads and get market research. The planned features, if realized, could make this site a unique hub in the clean-energy, green-building marketplace.

This post was updated to add a more detailed image of a quote from Sungevity.