You could completely eliminate all your lighting and electronics and it wouldn't make as much difference as that water heater. Heating appliances are the worst. Back in the 70's when, I was out of work, I sold roof-top solar water heaters for a while. They were popular for heating pools and spas. But they didn't make sense for replacing the home water heater unless you were housing the Brady Bunch. In Kentucky they'd be useless half the year.