Solar heaters are devices that provide energy in the form of heat for the purpose of heating homes, workshops, businesses or other locations normally requiring the use of conventional energy sources to maintain a constant temperature and to heat water. They are usually very simple in terms of use, once built requiring little maintenance to ensure continued effective operation. They are also relatively straightforward to construct and install, requiring a small amount of technical knowledge and experience of small home improvement projects.

     There are two main types of solar heaters: solar air heaters and solar water heaters. The former are generally used to heat the air in living areas and workspaces, while the latter are used to provide hot water for a variety of uses.

     Solar Air Heaters
     Solar air heaters are used to heat the air in living areas and workspaces, most commonly in locales where the air temperature is not constant throughout the year. Though there are many different designs of air heaters, they all have common elements as the basic premise is relatively simple. Cold air from the dwelling or workplace is drawn by convection over a surface designed to soak up the heat generated by sunlight. This retained heat warms the cold air, which then is pushed round the system and back into the area being heated. This in turn forces cooler air back into the system for warming, and the cycle begins again.

     While there are commercially available solar air heaters, the simple nature of the device makes it perfect for a not too challenging DIY or home improvement project. Most of the materials needed for a homemade solar air heater are commonly available and relatively cheap, meaning constructing your own air solar heater can lead to real savings on fuel bills. A sample list of components required for an solar air heater is: foam insulation, plate glass, thin sheet aluminium (often available from engineers and printers as refuse), aluminium foil, spare sheets of wood or plastic for the sides of the heater, and duct tape/glue and some form of sealant (builders caulk or similar) to hold the solar air heater together and to ensure the system is airtight. Depending on the design, the solar heater can be than placed in the appropriate position on or underneath the window, connected to a suitable gap allowing airflow from the house or workplace to the heating system and vice versa.

     Solar Water Heaters
     Solar water heaters have two main uses, namely the heating of domestic or commercial hot water systems and the heating of swimming pools.

     Solar heaters for heating home or commercial water systems and are simple in operation. Solar cells or panels are placed on the roof of the designated building, and connected to a solar storage tank. This storage tank receives water from the cold water system of the building, and outputs to the standard hot water heater. Water cycles between the solar collectors on the roof and the solar storage tank, heating the water contained there. It is only when a hot tap or faucet is turned on that water goes from the solar storage tank to the normal hot water heater, and it is only when the temperature of water needed exceeds that of the water provided by the solar water heating system that the conventional system activates and starts heating the water.

     Solar heaters for swimming pools and the like operate on a similar principle. The solar energy collectors are connected to the pools water system, with the solar heater directly warming the pool water. Using them can significantly extend the amount of days available for pool usage at little extra cost.
Many companies are now offering solar water heaters for purchase, and some governments and public bodies are encouraging their citizens to adopt this technology by making grants available to defray the cost of purchase and installation. It is possible for an amateur to make a solar water heating system, but this is significantly more complex than with solar air heaters. As a result it is advisable to purchase any solar water heater required rather than building from scratch, as is possible with air heaters.

     Benefits Of Solar Heaters
The main benefit of solar heaters is obvious. Both solar air and water heaters can significantly save on utility bills. Since each place of installation has different costs and requirements it is impossible to give precise figures on the savings to be made. However, it is likely that a large percentage of annual energy costs can be saved, especially if a solar combisystem is installed (one combining both air and water heaters). Depending on the initial outlay, a solar heater can pay for itself as early as two years after installation (though for bought rather than homemade systems this would take longer).
Another benefit of solar heaters is independence of energy supply. With the rapid growth of China, India, Brazil and other developing countries world energy demand is growing while supply is projected to decrease. Installing solar heaters will protect against the inevitable price rises, and against the blackouts that are likely to occur as a result of forthcoming shortages.