I have been looking into alternative energy recently for many reasons. (The main one is I don't want to sign an easement to the utility company here) Anyway the thing that seems to aggravate me the most out of all these systems is that they ALL rely on batteries. I hate batteries. They have two very serious drawbacks as far as I am concerned. 1) They are VERY expensive to purchase initially. 2) If you're lucky, they will last you 7 years, which leads us back to #1. So I have been looking for another way to store the energy produced during a good sunny and windy day. The only way I could think of was in the form of potential energy. That is to say... a pond. Here's what I would like to do. I would have a large storage pond on top of a hill. About 150-200 feet below this hill I would have another storage pond. I would like to run water from the high hill 150-200ft down a tube to a pelton wheel generator at the bottom. Then the water would run off into the lower storage pond. During the day and in times of wind I would use solar and wind powered pumps to pump the water from the lower pond back to the high pond. This higher pond would in effect, be my battery. Excess power not used by the home would be ran to an electric pump to push more water back to the high pond thus helping somewhat in the efficiency of the system. Having said that, I realize this is an incredibly inefficient system but once its up and running it would be a lot more cost effective than having to buy and maintain a battery bank. (which I will never do!) Now admittedly, I have had some problems in figuring some of this out because my math is a little rusty. All the formulas I have found are for running streams or rivers and nothing takes into consideration the PSI of a mass of water. How would I go about calculating how much water (gpm) I would need to generate 5kw with a head of 150-200ft starting with a stationary pool of water? My main fear is that it will require a larger gpm to power than my return pumps can recover during times of sun/wind. Lastly, is there anyway that I can increase the power output of a pelton wheel by changing the velocity or pressure of the water in some way? Would a 4 inch pipe leading 200 feet to the jet be better than a 1 inch pipe?