What should water temperature be during no sunlight periods, using a solar/electric water heater?

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Question by Cookin’ in Hawaii: What should water temperature be during no sunlight periods, using a solar/electric water heater?
We have solar water heating, but during off-peak hours, the electric water heater kicks in. ( Two hours in the evening and 1.5 hours in the early morning) The water is 140 degrees. Is this normal? I know the thermostat can be turned down on regular water heaters, but does it need to be this hot because of the solar? Water is scalding hot!

What do you think? Answer below!