Solar Water Heating

Solar water heating is the oldest and most practiced use of solar technology.

Here is a simple explanation of solar water heating.


The basics of the solar water heating technology can be seen in the above diagram. The solar collector (see Solar Collectors) absorbs the radiation from the sun and heating up water and distributing that to a storage tank which is then used throughout the house for hot water needs.

There are two main methods of solar heating: thermosyphon systems and forced-circulation systems.

Thermoshyphon System

The storage of water during non-sunny or nighttime periods is the reason for thermosyphon systems. The principle that these technological system uses is the fact the cold water has a higher density than warm water and therefore will sink. The water storage tank is placed above the solar collector to create a circulation of water. The cold water flow down through the collector is heated up and rises back into the tank. The consumer uses the hot water from the top of the tank. The thermosyphon system is generally used for small-scale hot water needs.

The following figure gives a strong visual representation of the thermosyphon system.


 Forced-Circulation System

Rather than using gravity, the forced-circulation system used an electric pump to move the water throughout the system. This allows for the tank and the collector to be installed separately. There are electric sensors which monitor the temperature of water from the collector and the tank. This trigger the pump to move the water throughout the system. This system can be used for moderate hot water needs and is very easy to implement in collaboration with an existing electric or fossil fuel system.

A forced-circulation system can be seen below.


Authored by: Chris Castello

Edited by: Sean Murphy


  1. This article could be a good start for a more extensive one dealing with solar systems.
    I read some articles, and they are well written, but if you accept good-willing comments, they need to be better organised and better interlinked (with something like a menu or something).
    Anyway, i like the simplicity in which you write.
    Keep up the good work.

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