What You Need to Know About a Closed-Loop Solar Hot Water Heater
Do you want to know a clean way to heat water? Why not put a solar hot water heater to work. It’s really not complicated. Just expose water to sunlight and voila - you have a non-polluting, efficient solution. I know this sounds simple and I promise I’ll elaborate – but first a little background info. As a DIY'er, solar water heating is much easier than generating electricity and is a more cost effective use of solar power. There are many types of heating systems available even a solar power pool heater that can save you big bucks.
You should know that there are really only three solar water heating systems that have been proven performers throughout the years. But all in all a solar panel water heater is a great solution in many ways. Even if you plan to install a full scale home solar system isolating the water heater portion is smart and economical. If you can heat the water with solar power (through the sun's rays), you'll save enough money on your power bills to get a better ROI (return on investment) for your home solar power system .
If you live in a cold climate you'll need an active anti-freeze system, and closed loop systems are probably your best choice. Now-a-days most solar based homes have the drainback solar water heater as a heating solution. If you're lucky enough to be living in a mild climate then you'll need a completely different type of heater. The best application for warm temperature climates is the something called an Integral Collector System. These are typically less expensive than their cold weather counterparts.
Watch this short but explanatory little animation about solar water heating:
The solar power collectors of your solar hot water heater are mounted on the roof. They are used to heat an anti-freeze fluid like Ethylene Glycol. This heater uses an exchanger to transfer heat from anti-freeze to the water. A temperature sensor is integrated which checks the temperature of the fluid and the warm water in the tank. With the anti-freeze liquid heated up, the pump is turned on to circulate the hot fluid. To make the system fail-safe there should be a backup means of heating provided so the water can be heated through traditional alternatives like gas or electricity.
The mounting of flat-collectors in the solar panel water heater is not important with regard to the distance from the exchanger making it suitable for almost any configuration. The best feature of a closed-loop solar hot water heater is that the pipes are filled with the anti-freeze so the pump does need not to generate a lot of pressure. Other solar heating systems like the drain back system put a lot more strain on the pumps because they would need to overcome the head pressure.
Due to the lower capacity pumps, you can power them with solar panels easily. The low capacity means that you do not require a lot of energy to activate them and this low power can be generated using PV panels. Of course, at night this system will not work, but who needs hot water at night anyway?
While the closed loop kits are readily available and simple to install, there are some challenges. If you do not fill the pipes properly with the fluid, you will get inefficient performance. If you plan to do it yourself, you need to take care to ensure the pipes are completely full with the liquid. There should not be any air pockets.
A solar power hot water heater system comes with a limitation, i.e. the antifreeze fluids deteriorates with time. Once overheated, the efficiency of the antifreeze liquids degrades and some of its by-products get deposited on the interior walls of the pipes of the collector. If you have an efficient system and do your maintenance, you should only need to replace the glycol solution once every decade. To do this properly you should get professional help when replacing the glycol in your solar power heater.
When there is strong sunlight the fluid in the closed-loop will need to be circulating at all times to prevent it from overheating. This will not only ensure a constant supply of hot water but will also help prolong the glycol's life. The use of a tempering valve is important in this case - you don't want that water to get too hot! The piping should be made of copper – as it’s the only material that works well at high temperatures.
Editor Note: These systems can also be used for a solar pool heater. We all know how expensive it is to heat a pool! The truth is that if you live in a multi-season region and use this economical solar heating system you'll extend your pool season by several months. They come as kits a or as a DIY project where you can save yourself some cash.