That might be compared to electricity, but the installation costs I was referring to was solar as compared to heat pump. Heat pumps are almost as efficient as solar, without the extra install costs. heat pumps continue to generate hot water on overcast days whereas solar installations are dependent upon sunlight.
And as far as yearly savings of $300 to $700, I doubt it very much. Anyone paying that much for hot water is using a lot of hot water. And as there are some days, perhaps many days where the solar unit because of poor sunlight, doesnt produce hot water, the unit will resort to booster element, which means electricity will be used and that means less savings, so $700 savings are very unrealistic.