Your water heating bill otherwise included into your overall bill, otherwise somehow subtracted from your over all electric bill if calculating in some kind of a separational way.
So one could say that their utility bill including everything is around $ 400.00 dollar's for the month, and so part of that being your water heating cost to you is say $20.00 of that utility bill in that month.
Ok, so you done the solar and cut that bill in half in which would be a savings of $ 10.00 dollar's on the overall. Hey every penny counts right ?