A Split Solar Water Heater is composed of:
Solar Thermal Collectors (evacuated tube or flat plate) which absorbs solar radiation (sunlight) and changes it into heat;

Solar Water Tank (Storage hot water tank) accumulates the hot water produced by solar energy so that it can be stored for use when needed;

Frame (bracket) which support the Solar Collectors and Solar Tank;

Accessories which ensure the regulation and the safety of the system;

Back-up heater (gas, oil, or wood fuelled boiler, electric immersion heater or heat pump) which will bring the hot water to the temperature required when there is not enough sunlight to do so (mostly in winter).

In most area, solar thermal collectors alone cannot provide all the hot water for a household's needs throughout the year. Correctly sized they will supply 60% of heat / domestic hot water needs. They are normally installed in conjunction with a conventional back-up heating system.

Circulating pump (only apply in active solar water heating) which transfers the heat from the solar thermal collectors to hot water in a solar tank;

Closed-Loop Active Systems

These systems pump heat-transfer fluids (usually a glycol-water antifreeze mixture) through the solar water heater. Heat exchangers transfer the heat from the fluid to the water that is stored in tanks. Double-walled heat exchangers or twin coil solar tanks prevent contamination of household water. Some standards require double walls when the heat-transfer fluid is anything other than household water. Closed-loop glycol systems are popular in areas subject to extended subzero temperatures because they offer good freeze protection. However, glycol antifreeze systems are more expensive to purchase and install and the glycol must be checked each year and changed every few years, depending on glycol quality and system temperatures.