As I understand it at least, if you put more power into the grid than you use from it then under federal law the power company has to pay you for it at whatever is the going 'whole sale' rate (what they buy it for from power plants). Now if you use more than you produce part of the time and figure it would average out you could probably have it credited to your account but you could also make them cut you a check. I havent done it but thats my basic understanding from some folks I have talked to who did.
your understanding is correct - for the most part. i think that the fed has some program that the power companies are required to acquire a certain percentage of total generated electricity from renewable resources - and the micro hydro would qualify i believe, as would solar and wind! however, the rate they pay is less than the rate they "credit" you if you "bank" your power that you produce - so if you are living on the property, you could generate enough power to basically have NO electric bill, and depending on the rate they pay out, if you didn't live on the property, you might make out!
