Now considering that Hot water is a large degree of people's electricity bills, would it make sense that solar panels and this thing would make a house a LOT more energy efficient?
Indeed, hot water is the second greatest energy consumer in the home, after space heating and cooling (food refrigeration is third). Solar hot water is much less expensive than photovoltaics, and is the most cost-effective application of renewable energy there is (other than clotheslines).
If you live in a climate with no hard freezes, the technology is simple and relatively inexpensive. If freezes are frequent or of long duration, system design must include glycol loops, circulator pumps, and heat exchangers, which adds to the complexity and drives up the cost, but even cold climate systems have a favorable payback time compared with electricity.
The most cost effective application of solar hot water is for swimming pools, because the delta T involved is very small and the amount of water to be heated is huge. A typical pool system consists of cheap black plastic tubes and a single circulator pump.
