I wish I had checked out the library copy before buying. If you're looking for a broad-based overview of eneregy options -- Solar, thermal, greywater, micro-hydro, landscape lights, bird fountains, etc -- this can be your one-shop-stop. Real Goods has blended energy overviews with their catalog, so if micro-hydro-electric (!?!?) interests you, then by all means look no further, Real Goods will be happy to retail out their product to you. However, I found most of the energy information available out on the 'net --free and more specific and informative, and alternate sources for energy products and options more abundant and lots cheaper.
If you have a serious interest in something specific, example PV systems, I found no single source, but recommend Kemp, "Got Sun? Go Solar" for helpful overview and great links and resources, and "The Renewable Energy Handbook", a better option to Real Goods. All from Amazon, and more applicable for actually getting greener and saving a buck in the process. These leave searching for the best and most applicable products and options to you, and there's much out there to choose from, and some very informative nuggets to be had along the way.
(FWIW: our city recently held a sustainable living fair, attended by Real Goods. But when I followed up on their "Call us when you're ready, happy to help you go green!", I received an abrupt "We don't service your area.". I guess green refers to the energy movement AND to those ready to cash in on it.)