I came across this pretty interesting article from Hank Green and the guys over at Ecogeek. Thought I'd share.
Solar water heaters are low tech. Basically, they're black pipes on panels. There's no nanotechnology, no monosilicon crystals, and no DC to AC conversion. Just run a pipe to your roof, through the panel, and then back into your house. In many parts of the US, solar water heaters can provide more than 90% of a household's water. And in all but the cloudiest climates, they can provide more than 30%.
A recent study compiled in the UK (notably, not the sunniest place on earth) has determined that the average household could save around $450 per year. Now, the numbers would certainly be slightly different for Americans, and city dwellers with less roof space might not have the same options. But even with a big chunk shaved off the top, $450 for, let's say, the 80 million American households that are ready for hot water panels, is more than $30 billion per year.