A new solar mandate passed last week makes the city by the Bay the leader in U.S. sustainability. As if San Francisco couldn’t get any greener.


San Francisco made history last week as the first major U.S. city to require solar installations on new buildings. The San Francisco Board of Supervisors passed legislation requiring new buildings to install solar panels or solar water heaters on their rooftops. The mandate, which goes into effect next January, applies to both residential and commercial buildings under 10 stories high. It also furthers the expansion of an already existing California state law that requires new buildings to make 15% of their rooftops solar friendly.


“By increasing our use of solar power, San Francisco is once again leading the nation in the fight against climate change and the reduction of our reliance on fossil fuels. Activating underutilized roof space is a smart and efficient way to promote the use of solar energy and improve our environment.” — Scott Wiener, member of the San Francisco Board of Supervisors and legislation sponsor.


San Francisco, however, is a seemingly ironic city for solar. A common misconception that California as a whole is all sunshine and palm trees, San Francisco is notorious for it’s cloudy and chilly weather. Cue Mark Twain’s famous quote about the coldest winter he ever spent was a summer in San Francisco. The fog here is so ubiquitous that locals even gave it a persona—the apathetic Karl the Fog, complete a Twitter following. You’d think rooftop wind turbines would seem more appropriate. Luckily, rooftop solar does not in fact require a blazing sun all day long. Counterintuitively, solar technologies work more efficiently in cooler temperatures. Germany, for example, being one of the coldest and cloudiest countries in the E.U., is the world leader in solar and produces 5x more than the U.S.  


This poses a number of questions in the debate of whether solar is a friend or foe to the grid. While utilities have argued that if more consumers use solar to lower their monthly bills, then there are fewer funds to pay for maintenance of the power grid. This new regulation will hopefully prove successful for California, and spare customers from being triple-charged by utilities, as those in Nevada have suffered. Regardless of which side of the solar panel you are on, having a surplus of solar will lower the demand and price of power, which, in an expensive city such as San Francisco, wouldn’t be such a terrible thing. So back off, Karl the Fog.