How Solar Works

How solar water heating works

All solar water hot water systems have at their core a range of very similar operating principles.

Getting started

The driving force of a solar water heater is the solar collectors. These consist of absorber plates covered in a black (or very dark surface) that is exposed to the sun. When the sun’s rays fall on the absorber plates, the energy contained in the solar radiation is converted to heat (that is, into thermal energy). To understand how Envirosun systems maximise the amount of solar energy collected, read: More heat than light. To reduce the loss of collected energy back to the environment, the absorbers are usually placed within a solar collector comprising an insulated case and a transparent (usually glass) cover. To learn more about how Envirosun solar glass works, read: The results are clear


Moving along

The absorber plates are filled with a liquid, the purpose of which is to transfer heat from the absorbers to a heat store. In most, but not all, cases, the liquid is simply water – the same water that will be consumed as hot water in the home (these are called open-circuit systems). Sometimes the liquid in the absorber plates is not consumed but instead re-circulates between the absorbers and the heat store as part of a closed-circuit. The heated absorber plates conduct their heat to the liquid to begin the process of storing the solar energy.The way that the heat is transferred from the absorbers to the heat store depends on the type of solar hot water system. Thermosiphon systems, such as the Envirosun TS range rely on the natural tendency of hot water to rise to replace any cooler water that is above it. To understand this process in detail, read: Staying close to the action. Other active systems, such as the Envirosun AS use an automatically circulating pump to achieve the heat transfer. To learn how this is achieved, read: Information is power.