Residential solar panels remain one of the most accessible means of using solar energy in a home. Solar panels can be used to provide hot water and also for space heating. There are several different types of solar collectors to choose from. Each type of solar panel has the same goal, to efficiently transfer the rays of the sun into energy that can be used in the home.
Flat plate collectors are the most common type of residential solar panels. This kind of collector consists of an insulated box covered with a plastic or glass top. In the bottom of the box is a black absorber plate. On top the absorber plate are flow tubes filled with air or liquid. When the solar rays hit the absorber plate it heats up. At this point the energy is converted from solar energy to heat energy. That energy is transported from the collector into the home by the air or liquid in the flow tubes.
Liquid collectors are similar to a flat plate collector but in this case the energy generated is generally used for heating water and less often for space heating. The flow tubes lie directly on the absorber plate. As the water in the tubes passes into the collector and over the absorber plate it is heated. Then the water exits the collector and is sent to a storage tank for use. This is a “direct” or “open loop” system. Unglazed residential solar panels are used to heat swimming pools.
The other type of liquid collector is an “indirect” or “closed loop” system. In this type of system the liquid in the flow tubes is filled with a heat transfer liquid. The liquid is heated up as it passes through the collector and when it exits it goes through a heat exchanger. The heat exchanger, usually in a hot water heater tank, then heats the water for use in the home. Residential solar panels of this type are often used in climates where water could freeze in the flow tubes in the winter.
A simpler type of residential solar panels, air collectors force air into the collector where it picks up heat from the absorber plate. That air is then directed into the home for space heating. It is a less efficient system than an air or liquid collector that used flow tubes. And often fans are needed to push the air into the collector which uses electricity. The advantage is that they do not freeze or boil as liquid systems can in extreme weather. Leaks are easier to fix and less expensive materials can be used to construct the collector.
To choose the right residential solar panels the homeowner must calculate the energy he needs to produce, the climate, and the budget for the project.