In US, the reason why solar hot water heating is not popular has to do with the more and more popular use of solar polar to generate electricity. Solar panel can generate electricity, and the electricity can be used for many purposes -- not just for heating water. This means the use of solar panel is more flexible than solar hot water heater. We also need to consider the fact that our roof is a limited asset. If we put a solar hot water heater in one corner of the roof, that space is taken, and we cannot put a solar panel in the same place. This becomes an "either-or" question. You use either solar hot water heater, or solar panel. Cannot have both -- at least not in the same space. Once a homeowner has decided to use solar panels, he is not going to add solar hot water heater into the mix. Not only the fact that it would have taken up room that he could add solar panel, but also this would have added complicity to the HVAC and plumbing systems. This probably explains other reasons why solar hot water heater is less and less popular.
@@tianxiu Agree with you. In an off-grid situation, the house-owner needs to get as much energy as possible because there is no grid-power as the fallback option. Of course, an off-grid house-owner can use a wood stove to heat the water; but there are so many works related to using a wood stove (cutting wood, stacking up wood...), and using a wood stove is not appropriate in a mild climate. In that case, a solar hot water heater makes a lot of sense.
@@lawrenceli4147 Wage in US is indeed high, and the electricity cost "may" be relatively lower than other places. Please note that these factors affect BOTH solar panels and solar hot water heater. Here, we see more and more people having solar panels in their roof top; but we don't see any one installing solar hot water heater any more. If high wage and low electricity cost were the determining factors, we would not have seen solar panel becoming popular -- instead, we would have seen both solar panel and solar hot water heater to go extinct. But this is not the case. Solar panel wins over solar hot water heater has to do with the simple fact that solar panel is a much better product - simple to install, very little maintenance, very versatile, suitable in many different regions, price is lower and lower while efficiency rating is getting better and better. If price of solar panel stayed high, solar hot water heater would have a place in the market. With the price of solar panel drop down significantly in recent years, there is no reason to choose solar hot water heater any more.
