Lots of L.A. County Rooftops Ideal for Solar Power, Finds UCLA Report

Close to 1.5 million rooftops throughout Los Angeles County could potentially be doubled as renewable energy generators. That's according to a report released last week by UCLA's Luskin Center for Innovation. The Los Angeles Solar Atlas contains over 40 maps breaking down potential solar density in cities, utility jurisdictions and political areas like the 15 L.A. city council districts. All told, there is enough plausible rooftop space, mostly on single family homes, to spawn over 19,000 megawatts. To put that in perspective, the Los Angeles Department of Water and Power's highest-ever peak was 6,177 megawatts on a blistering hot day in September 2010, but generally speaking the daily energy demand of Angeleños is much lower. In fact, the total rooftop solar potential within the city of Los Angeles is over 5,500 megawatts, which is enough power for city on most days.

But don't get too excited because it is not as easy as it may seem. As the report's authors duly note, the maps are best used for identifying large areas where there is great potential for solar on rooftops, but "they are an incomplete tool for investigating individual sites" since numerous factors--age, materials used, unusable portions, shade from trees--was not noted for individual roofs.

Another problem is that solar power only produces energy during a sunny day. Because power is generally not stored, a city cannot solely depend on solar and must turn to other sources such as clean ones like wind and dirty ones like coal, which L.A. is been trying to ween itself off by 2020.

For environmentalists, however, bringing utility scale solar power to the built environment should be considered before taking over large swaths of pristine California desert land. In a blog post, the group Solar Done Right notes that L.A.'s solar potential is "more than five times the output of the desert-destroying 9500-acre Blythe Solar Millennium project."

And if companies need to use the desert for such installations, they should use already disturbed land like properties once used for alfalfa farming or the selenium-plagued Westlands Water District in the Central Valley, desert advocates say.

Although every rooftop identified in the report may currently not be solar-usable, it is noted that this should be considered a long-term estimate as it is assumed rooftops will be replaced, thus upping the solar potential, in 10 to 15 years.