What is interesting to me is that the government still has not figured out a way to tax harnessing sunrays. I would imagine if 90% of the population were using solar water boilers, we would have a whole bunch of taxes on sunshine. Anyway, on the topic of which is the best solar water boiler:
Solar water boilers work in every climate, for most of the time in a year. By harnessing the sun’s energy and transferring it into water the miracle that is hot water is created. The guilty heat is absorbed by one of three types of solar collectors (mind you, these three types are only used for residential application).
Flat-plate collectors are well insulated boxes. They have a dark plate located under a plastic cover. These are called glazed flat-plate collectors. There are also unglazed collectors, these are lonelier and miss the cover.
Integral collectors, also known as batch collectors, feature several tanks, black of colour, fitted in an obviously insulated box. These types of collectors preheat water which then continues happily to the ever-present back-up water boiler. These collectors also run the risk of freezing.
Evacuated tube collectors are probably the most common types of solar collectors. And the cleverest if you ask me. What you do is get a couple of glass tubes and fit them inside each other. Vacuum the area between them and you pretty much eliminate heat loss.
What is the best solar water boiler system?
There are several types of solar water boilers. However, depending on climate, some solar water boiler types work better than others.
Cold climate – desperate times call for adequate measures
For this type of climate closed loop drain back solar water boilers are best. These solar water boilers use distilled water as the middle guy. A heat pump moves the water around whenever it is on. When it is turned off the water retreats in a storage tank. This is a clever way to achieve freeze protection.
Most drain back systems can go on for more than 15 years, and with proper water boiler maintenance can keep functioning even after two decades. The drawback is that you need a rather large pump powering your water. Also, the longer you make water travel the more energy you use. But hey, it is cold climates we are talking about.
Moderate climate – you can forget about the bear fur
Standard closed loop systems are good choices. You can still go for a drain back version if you require freezing protection. Active systems use heat pumps and valves to prevent freezing, a much-desired feature if you are in such a climate.
You are looking for flat-plate active closed loop solar systems. The heat exchanger loss inhibits the water boiler performance in warmer climates; thus, it is best suited for this situation. Another benefit of the active system is that the storage tank does not even need to be near the solar panels.
Warm climate – le creme de la creme for solar water boilers
Passive systems are interestingly efficient in warmer climates. Typically, passive solar water boilers are not as good as active systems. However, they are cheaper, more reliable and have longer lifespans. Of the two types of passive solar water boilers (thermosyphon and integral collector systems) integral collector storage systems are the best in warm climates where temperatures do not fall below freezing.
Figuring out what solar water boiler is the best becomes much easier as your options dwindle depending on the climate around you. Also remember that most solar water boilers will not work all the time, so you will need some form of backup water heating to protect you from potential stagnation problems.