How Does a Solar Water Heater Work?
The solar collector is mounted on or near your home facing south. As the sunlight passes through the collector’s plastic or glass “glazing,” it strikes a metal or rubber absorbing material. This material converts the sunlight into long wave heat, and the glazing prevents the heat from escaping much like a greenhouse. It is like leaving a car parked in the sun with its windows rolled up. The temperature inside a glazed solar collector on your roof can easily reach 300°F when there is no heat transfer fluid flowing through it.
Because of their high performance, simplicity and cost effectiveness, the most common types of solar collectors used in solar water heaters are glazed flat plate collectors. A glazed flat plate collector consists of a shallow rectangular box with a transparent plastic or glass “window” covering a flat black plate or selective “Chrome” coating. The black plate is attached to a series of parallel tubes or one serpentine tube through which water, or other heat transfer fluids pass.
2. Energy Transfer: Circulating fluids like water in an “Open Loop” or Propylene Glycol in a “Closed Loop” transfer the collected energy in the form of heat to a storage tank. Heat energy is transferred from the collector to the water storage tank. In some water heaters, hot fluid is pumped from the collector to the storage tank. The pump is powered by electricity that either comes from an electrical wall outlet or a small photovoltaic module located near the collector.
3. Energy Storage: Solar-heated water is stored in an insulated tank until you need it. Hot water is drawn off the tank when tap water is used, and cold make-up water enters at the bottom of the tank. If additional heat is needed, it is provided by electricity or fossil fuel energy by the conventional “backup” water-heating system.
Why not use a PV system to heat my water?
Understanding the difference between solar thermal energy and solar electric energy is very important. Solar Electric is more commonly referred to as Photovoltaic (PV), in which energy from the sun is converted to electric power. Solar Thermal energy, however, simply uses energy from the sun to heat water. Both PV and Solar Thermal technologies can be used together or separately. While PV is used to power the electric needs of an entire home or building, Solar Thermal is the best choice for solar water heating because it can produce 4 times the power of the PV with 1/3 of the price.
So a 60 square foot Solar water heating system can produce over 3 KW of thermal power.
Why should I go Solar?
- Financially smart, the sun is free, it makes sense!
- Reduces Pollution up to 8 tons of CO2 annually per family.
- Socially Responsible Reduces Dependence on Foreign oil.
- Increases the value of your home, people love frugal energy houses.
- Never run out of hot water.