The water can be heated for an array of uses, including home, business and commercial uses. Heating pools, under floor heating or energy input for space cooling or heating are typical examples of solar heating.A sun-powered water heating system can form part of a solar thermal cooling system, promoting efficient temperature control over buildings or parts thereof. During cool conditions, the same system can supply hot water. Solar heating of buildings in temperate climates has a season-problem: In winter, when most heating is required, least is available from the sun. This may frequently be disentangled by storing solar heat in the ground or in groundwater (Seasonal thermal store).

The type and difficulty of a sun-powered heating system is typically decided by:

* The changes in background temperature in the day-night cycle.
* Changes in background temperature and solar power between summer and winter.
* The temperature of the water needed from the system.

The minimum potency of the system is decided by the amount or temperature of hot water needed in winter (when the biggest quantity of hot water is typically needed). The top performance of the system is set by the necessity to stop the water in the system from becoming too hot (to boil, in an intense case). There are 2 main classes of sun-powered water heating systems. Passive systems depend on convection or heat pipes to circulate water or heating fluid in the system, while active systems employ a pump.

Additionally, there are a number of other system traits that distinguish different designs:

* The kind of collector used (see later)
* The positioning of the collector - roof mount, ground mount, wall mount
* The locale of the storage tank re the collector
* The system of heat transfer - open-loop or closed-loop (through heat exchanger)
* Photovoltaic thermal compound solar collectors can be built to produce both hot water and electricity.