A solar water heater utilizes the sun’s energy instead of electricity or gas in order to heat water, hence resulting in lower monthly utility bill. Once installed correctly, solar water heaters are far more economical and cost effective as compared to heating water with electricity, dedicated heat pumps, heat recovery units or propane.
There are three kinds of solar systems that are commonly used. These include, pumped, integral collector storage (ICS) and thermo-siphon. The direct circulation system transfers potable water from the water storage tank through one or more collectors and back into the tank.
The solar collector is the key element of the solar heating system. It is basically a metal box which has insulation and a black absorber plate. The purpose of it is to gather solar radiation and heating the water. The circulating pump operates with the help of an electronic controller, a common appliance timer, or a photovoltaic (PV) panel.
The process is as follows:
1. In integral collector storage systems, the solar water storage system is built into the collector.
2. The potable water in the collector unit is heated through sun and distributed by city or well water pressure to an auxiliary tank, which contains non-solar back-up heating, or directly to the point of use.
3. A thermosiphon solar water heating system has a tank mounted higher than the collector (usually on the roof) to supply a natural gravity flow of water. Hot water goes up through the pipe in the collector, which is mounted below the tank; heavier cold water sink down to the lowest point in the system (which is called the collector), displacing the lighter hot water which rises up to the tank.
Since the ICS and thermosiphon systems use no pumps or controllers and water flow or run through the collector, they are relatively simple to use.