Get a programmable thermostat for your water heater = turn the temps down an hour or two after you go to bed, or during the warmer times of the day, or the times when you typically don’t use your hot water. No reason to heat what is not being used!
DIY Solar Water Heater (how you can save over $200 year) - If you are looking for an effective way of reducing your monthly energy bill you might be considering a DIY solar water heater. With no doubt, solar water heating is definitely one the most cost efficient and effective ways of lowering your bill. Most homes use around $1,200 of energy per year... - http://www.solarenergyformyhome.com/diy-solar-power/diy-solar-water-heater/