Solar water heaters have been around for a long time now. But, unfortunately, they haven’t taken off as many had hoped they would. We were all supposed to be getting our water heated by the sun by now, but that’s not how things panned out.
Solar water heaters work differently from solar panels. In a solar panel, special materials convert energy from light into electrical charge which you can then use for appliances around your home. But in a solar water heater, the sun simply heats up water in specially-made tubes and then a pump distributes it throughout your home, including the bathroom. These devices, therefore, are considerably less high tech than you might imagine.
With that said, they come with some benefits. For one, you don’t have to spend money on gas to power your boiler, which is already a massive bonus. Plus, they work automatically, providing hot water the moment the sun comes up into the sky. However, there are some downsides that make them a poor boiler replacement.
Unsuitable For Areas That Get Freezing Temperatures
Because solar water heaters rely on water-containing tubes exposed to natural sunlight, they are unsuitable in areas where temperatures fall below zero, including at night. That’s because the water in the solar pipes freezes and expands, causing damage to the surrounding structures.
The best location for solar water heaters, therefore, is in sunny areas that can experience the occasional cool day.
Indirect circulating systems get around this problem by using a two-stage transfer system. Instead of putting water in the solar heat collector, they use a non-freezing fluid alternative. A pump then circulates this to a heat exchanger within the home which then heats the water. It sounds a little round-about – and it is – but it eliminates the risk of freezing weather damaging your system.
The problem with these systems, of course, is the price. Because they have so many more parts, they can be much more expensive to install than direct circulation systems. And that can make them uneconomical compared to convention appliances.
Unsuitable For Some Roof Designs
Lack of suitability is another problem that homeowners can run into when trying to install solar heaters. In thermosiphon systems, for instance, warm water rises and cool water sinks in a heavy storage tank. The system is efficient and works reliably. Unfortunately, though, it isn’t suitable for all roofs because of the weight of the storage tank. Furthermore, it can be even more expensive than indirect circulating systems, even though heat transfer is passive.
Scaling Can Become An Issue In Some Areas
Depending on where you live, scaling might also become an issue for you. In hardwater parts of the country, the mineral content of the water can be so high that it leads to deposits on solar heating systems that can eventually cause them to fail.
The solution is to continually add softeners or mild acidic solutions to flush them out. Ideally, you’ll want to do this every three to five years for direct systems.