Additional way to get the benefits of solar if you don't have a roof: the First Parish UU in Arlington Center is the host for a Community Solar (http://www.mass.gov/eea/energy-utilities-clean-tech/renewable-energy/solar/community-shared-solar.html) project. Anyone in eastern MA can buy one or more of their 210 panels for $328 each, which allows you to get a one-time 30% federal tax credit, and net metering credit against your residential electric bill from the panel(s) for 10 years (after that you return ownership to the church so they can start getting solar power themselves).

My household just purchased 8 panels (we would need to cut down 3 big oaks to use our own roof). Click this link for $25 off (http://www.arcadiapower.com/elizabeth8542) (I also get $25 off), or this non-affiliate link (http://www.arcadiapower.com/solar), for information. At the moment there are 144 panels still available.