Experience with non-PV solar technology?

Does anyone out there have experience working with non-photovoltaic solar technology? Anything from the theoretical to building your own solar hot-water heater? I've got a writer friend who is working on an article on solar thermal technology. She's especially interested in talking to people who have experience with small-scale projects (like a water system for a home), but she's interested to talking to anyone who can help her understand the background, too.

I vaguely remember talking about semi-off-the-grid ideas when I was in high school. (A friend had an indoor swimming pool that may have been partly solar, but I think it was also heated by a wood stove. That was Maine, and the sun doesn't shine as much there as it does in Colorado.) But although I know people from grad school who rebuilt diesel engines to run on used cooking oil, it's been a long time since I've talked to anyone who does their own passive solar. (Beyond south-facing windows, that is.)

If you've got experience or know people who do, could you e-mail me (shearsensibility AT gmail DOT com), so I can pass contact information along to my friend?

Sprawl and the solar energy space problem

I've been fascinated by solar energy since the late 70's, but I recognize that there are practical problems associated with using it to replace fossil fuels right now. Efficiency of photovoltaics, cost, storage... ok, yeah. But there's one problem that has had me scratching my head since I moved to the Southwest: finding a place to put the panels.

The arguments seem to assume that the energy must be produced on land that's currently open space, disrupting the ecosystems more than a coal mine. But I look around me and see the ecosystems disrupted anyway... by shopping malls and big box stores and parking lots. And I've wondered: why couldn't all those rooftops be used to generate electricity?

Well, it turns out that they can be.

According to the New York Times, stores as diverse as Wal-Mart and Whole Foods are installing solar panels on their roofs. The efforts are concentrated in places with major tax incentives (which include New Jersey and Connecticut, which don't strike me as the best places for solar power) - the panels are still too expensive to compete with coal and natural gas. But if the costs change... Arizona and New Mexico, I'm looking at you.

And if that works, you know, they could cover those acres of parking lots with roofs, if they want more space.