One of the innovations we have made is a hydro generator where we would connect a small generator to the house 20mm pressurized water main and also to each of the down pipes.
We entered into the post conceptual phase this week. Very quickly we have encountered the following issues:
generator either needs to be small (low resistance) but high revolutions of 5,000 or so which will be very hard to achieve on a regular basis
higher voltage generator but more resistance - meaning this is unlikely to work for down pipes.
We also looked at wind turbine motors and siphon systems. Any of these work in principal, but we did a calculation of what they are likely to generate in terms kW and the result is around 0.5% of what we get from our solar system.
So the question is whether it is even worth pursuing this innovation. Its cool and in principal a good idea, but perhaps a waste of resources for now given that our solar roofs are so incredibly impressive.