Thanks for all the input. I am considering a 12v electric heater similar to Boywonder’s system explained above, with the 2.6 gallon Rheems WH (or the 4 gal Isotemp tank, still trying to decide what fits best). I will use a 300 watt, 12 volt element in place of the 1400 watt element.
I want to capture the excessive solar energy, after the batteries are charged and direct that power to the 12 V element. 1der uses his solar controller to direct the the power to his 12V element, but I am considering using the Victron BMV-712 battery monitor. It has a relay output that can be triggered, based on state of charge (SOC) of the battery. The solar controller would supply power to the batteries. When the SOC hit 100%, the relay would be energized and the WH would draw from the batteries, until the SOC fell to 90% (or whatever settings makes sense).
My thoughts are the batteries would be charged in the mornings until the SOC hits 100%, and then the water heater would be heated on and off throughout the day, hopefully maintaining a level of heated water. If the water did not get hot enough, I would flip the switch and direct power to the WH. Even if there was not enough solar energy to get hot water, it could keep the water above ambient temperature, which would reduce the power required to reach hot water.
The sketch below is a high level view of how I would wire this setup. The relay that powers the WH could be energized by either the BMS or a switch. This is not a schematic with fuses, wire size, etc, but just a conceptual drawing.
Any thoughts or feedback?