I’ve been thinking about a lunch conversation I had recently with Pamela Frickmann, one of the Sacramento Tree Foundation’s friendly neighborwoods foresters. We were discussing the apparent discontinuity between recognizing the benefits of tree shade for homes versus the desire to expand localized solar power when she brought up a very good point: “Why does local solar power have to be on individual houses? Wouldn’t it make more sense to install twenty homes worth of solar panels on top of, say, the new Target on 65th Street, and provide trees to shade the twenty homes instead?”

Good point. Let’s explore that idea:

The basic structure already exists. SMUD recently introduced a pilot program called Solar Shares where renters, condominium residents, and homeowners with roof shading can obtain the benefits of having installed solar by investing in a ‘virtual array’ – a segment of a local solar farm being built on behalf on SMUD in the nearby area.

Sacramento is home to millions of square feet of commercial office and retail space. Many of these buildings are far too large to receive any real benefit from adjacent trees, and instead rely on roofing materials with a high reflectivity index to reduce their cooling load as well as the urban heat island effect. Now imagine if instead we simply covered large proportions of these rooftops with solar arrays, using the Solar Shares program to offset the installation costs. The benefits would be threefold: SMUD would be able to much more quickly meet its requirements for solar power generation imposed by the State; commercial property owners would derive a potential micro-income stream from a building component that is usually a net drain _and_ the reduction of UV exposure would likely increase the lifespan of the roofing materials; and Solar Shares participants would have far more ‘virtual array’ credits available to them.

And of course, we would then be completely unfettered in our regional pursuit of shade for homes. Long live the urban canopy…