your still going to use the same amount of electricity to heat your water to a given temperature even using a timer switch , but heres one that would do the job.
As I said, I don't care about electricity use. I only use the solar water heater because it was already installed when I moved in.
A timer wont work for me. My system has too many manual controls.
but as I said what you really need is good thick insulation
so that your water heater does not loose the heat that you are paying for when your not using it.
You can't insulate the collector. That's probably by far the biggest heat loss apart from turning on the tap. Well OK maybe you can, you could have some glass/etc covering with a vacuum gap under it. Then the sunlight can get through but heat can't convect out. It would even block radiated heat like a greenhouse. Now I think about it, I've seen solar water heaters that seem to have glass coverings, maybe it's common. Mine is just metal pipes.
