We looked into it when we moved to New Mexico (where the sun shines most of the time), and it would have cost several thousand dollars and would have taken 10-15 years before the break-even point, as far as hot water production alone is concerned. Since then, however, the local utility company has set up a scheme that lets you sell excess power generated to them, so it is now a much more plausable idea. Definitely look at a power generation and storage option as well as hot water.