It occurred to me the other day that in a sustainable energy system the most expensive and nonrenewable part of any energy system is the batteries.
in the search to replace batteries as a power source i made a simple observation that hydro electric power can be scaled down to what ever size you can afford.
This led me to the thought that you could use water as a battery on a small scale>
If you have a swimming pool, all you need is a large water tank, placed above the level of the pool (possibly on the mound of earth left after digging the pool)
Pump the water out of the pool into the tank during the day using wind and solar powered pumps.
When needing electricity run the water back into the pool through a pico-hydro generator, there are many plans on the net for such generators – this should give you a few hours of power each day
if you do hyrdophonic/aquaphonics this system can be intergarated with that system to allow a constant flow of power and of water to the systems