$1500 of solar PV will pay off quicker than $1500 of hot water. Grid-tied PV is nice because you aren't going to run out of capacity to store the hot water and then be stuck and you lose a bunch of efficiency in the winter when they are surrounded by snow. I think even though $1500 doesn't get you too far into the PV game but $1500 of the contribution to the solar would make a good match for a heat pump water heater and/or one of the super efficient inverter mini-splits used heating and cooling. With natural gas being super cheap(relative to electric resistance heating) and the lack of gas water heaters that tie into solar hot water, the amount of resistance heat you need to use in the winter makes for a payoff period that is extremely long. The solar PV installer that lives down the street from me says it takes about 30 years to pay off even a 2 panel water heating setup and the plumbing isn't easy or cheap and there is more maintenance than PV. He showed me his eGauge power usage and in the summer and some of the swing seasons it keeps up with the usage but in the winter, when you need it more, you get less.
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