A solar water heater can operate together with your current electric or fossil-fuel water heater to supply a portion of the home's total hot water heating requirement. This will reduce greenhouse gas emissions, air pollutants and the cost of your water heating.
You can find plenty of water heating systems using solar energy today, including home-built designs that are simple but effective, like the batch heater. This design has no outer jacket or insulation blanket but is painted black and placed in an insulated plywood box. There is a plastic or glass glazing covering the assembly, which is angled to solar south. Pressurized domestic water goes into the tank’s bottom and heated water comes out from the top to your home’s hot water heater.
When your system is installed and operating, you can monitor its performance through the storage tank temperature and the heat exchanger’s inlet and outlet temperature difference. Tiny, slow leaks are tell-tale signs of poor performance and can be monitored on the pressure gauge. When the temperature of the circulation fluid changes, the system pressure rises and falls but the average pressure at rest should be the same throughout.
Grounding is used to dissipate electrical energy safely when faults occur. This is the third pin on your extension cord plug which allows electricity to flow when system insulation fails.
As soon as you start looking into a solar thermal installation, you will run into certain terms and principles that may be unfamiliar. It is essential that you understand these ideas, so that you can see what is needed and make intelligent decisions when offered choices by professional installers.
One of the advantages of a pressurized solar hot water system is that the solar loop is always full. This means that the pump has no static head pressure to overcome (just friction head), so low-head, slow-starting pumps can be used effectively. And those pumps can be run on power from a PV array, eliminating your grid-tied power costs for operation.
Drainback solar hot water systems are not as flexible as pressurized systems, but still work very well in both residential and business applications. They are very efficient if they are planned and installed carefully.
These systems have many advantages:
It's also important to consider these disadvantages:
Drainback installations use three tanks to heat the domestic water supply. The two main tanks are just like those used in pressurized solar thermal systems. However, the third is specialised – the drainback tank, which is installed on the solar loop.
The two main tanks are installed in standard fashion: the one heated by solar energy is piped in series before the backup grid-tied tank, so that the sun-heated supply is topped up with heat in the second tank if necessary.
Unlike pressurized installations, drainback solar hot water systems have a fair amount of head to overcome before they start operating properly. Consequently, they need more powerful pumps. The choice of pump is absolutely critical to the system.
