The term "solar heaters" may refer to several different types of heaters, but all are powered by energy collected from the sun. Some use solar heaters to heat individual rooms or entire homes, some use solar heaters to heat the water used in kitchens and bathrooms, and some use solar heaters to heat swimming pools. There are many ways to use solar heat. Though each of these uses solar energy in a slightly different way, all are based on the concept of collecting, storing, then using the energy available from the sun, which can save money as well as reduce the amount of non-renewable energy sources used for heating.
Solar heating systems are considered to be either active or passive. An active solar heating system uses electric fans or pumps to transfer the solar heat collected by either air or liquid. A passive solar heating system is one that does not require any mechanical or electrical parts to distribute the solar heat. A passive system requires a specific home design to enable it to collect and distribute the solar energy without the aid of electrical fans and pumps.
One of the most common types of solar heaters is the space heater. To collect solar energy to power a solar space heater, a solar panel is the typical apparatus employed. The solar panel collects the energy, then sends it to either a place of storage or directly to a solar heater for immediate use. Since the sun is not available at all times and weather conditions may prevent solar energy collection on certain days, it is important to have a reserve of energy available. This reserve is stored in a container that is usually some sort of deep cycle battery.
Solar space heaters are generally used to heat individual rooms. Heating only the rooms used is the most efficient means of heating a home, since central heating systems produce heat in every room, essentially "wasting" some of the heat. However, central solar heating systems are used to heat entire houses. These systems distribute the solar heat using air or a heat transfer liquid. Central systems usually require a backup heating system for days when the solar energy available isn't enough to heat the entire house.
Solar water heaters often serve as their own collection and distribution system. Many people build these on their own by simply painting a water tank black and allowing the tank to do the collecting work. Like the other types of solar heaters, these are either active of passive systems. Active solar water heaters employ electrical or mechanical pumps and passive heaters are simply positioned and designed to collect and distribute on their own.