This month's issue of Fine Homebuilding includes a detailed article on solar hot water heating systems.
The basic idea is this: if you want to cut your carbon emissions or reduce your energy bills, you get a much bigger bang for your buck by installing solar hot water instead of photovoltaic. It turns out solar water even pencils out in cloudy climates like Oregon and Vermont -- you just need more panels.
If the idea of solar hot water makes you think of the nice family that no one would talk to after they put giant, ugly panels on their roof, rest assured that the technology has advanced since the 1970's. The article details four basic ways to rig up the system, and while we don't have space to get into it here, the indirect method lets you use compact and attractive evacuated tube collectors like those shown above. Check out Metaefficient's post for more info on them.
Economic calculations are a bit problematic to us -- should we really think of saving the environment as something we should do only if we can afford it? That said, depending on your state's climate and incentives, it's quite possible to get the same energy and carbon savings out of a $6,000 solar hot water system as you would from a $30,000 PV system.
The Fine Homebuilding article is available online to subscribers only, but the article alone is worth the price of the magazine. Or do the green and socially sustainable thing -- check it out at your local library.
image via Metaefficient post linked above