The Solar Map

How much do you think you’ll cut from your monthly power bill with that fancy home solar system you’re planning to install?

It’s pretty hard to tell. Sure, the manufacturers can tell you how much power the solar cells are capable of putting out, but we know that’s always a best-case scenario, and life rarely follows the best-case script.

That’s why the San Francisco Solar Map is such a great idea. This interactive Web site has a map of the city, with dozens of color-coded dots representing residential and municipal solar projects. Click on a dot to open a window showing the size of the project, the company that installed it, and in many cases, the actual output and annual cost savings.

This is particularly useful in San Francisco, aka Fogtown, where the oh-so-moody fog can really cut into the efficiency of solar energy systems. If you live in the fogbelt of the city’s north-west corner (where I spent a large chunk of my youth – shout out to the Richmond and Sunset districts!), there’s probably a big difference between what a system is capable of putting out, and what it really does.

Well, according to this map, the 7 kW system at 36th Ave. and Geary, puts out 14,400 kilowatt hours per year, saving the owner $4,800. And the 2.3 kW project down the road at 23rd Ave. and California generates 1,900 kilowatt hours per year. The owner of that one includes the helpful note that “Every kW generated locally is one less kW produced by fossil fuels.”

Someone who is casually considering a home solar system could easily be put off by the up-front costs, which can easily reach $20,000 or more. But when the guy down the street says he’s saving close to $5,000 a year, it can make the expense seem much less daunting. Now that’s news you can use!