Solar hot water systems in a nutshell


Solar hot water systems use energy from the sun to heat water. The technology for harnessing solar energy for thermal energy (heat) is known as solar thermal energy (STE). STE is different from photovoltaic technology, which converts solar energy directly into electricity.

Domestic solar hot water system installations are typically of 2 types:

Passive, or compact, solar hot water systems

These systems function by natural convection or use heat pipes to transfer the heat energy from the collector to the tank.

Active, or pumped, solar hot water systems

These systems employ a pump to circulate the water, or heat transfer fluid, and a controller to turn the pump on and off depending on the temperature of the tank and collectors. Active systems are usually more efficient than passive systems but are more complex, more expensive, more difficult to install and rely on electricity to run the pump and controller.

Both installations typically require an auxiliary energy source such as electricity, gas, fuel oil, etc that acts as backup when the stored water falls below a minimum temperature.

Components of a domestic solar hot water system are usually:

Solar thermal collectors

The most common type of solar thermal collector for hot water systems is a flat plate which is fastened to the roof of a building, on a wall facing the sun, or free-standing.

Fluid system

This moves the heat from the collector to its point of usage storage tank. The system may use electricity for pumping the fluid, and have a reservoir or tank for heat storage and subsequent use.


Recommended reading

Solar water heating / Wikipedia: 2009
http://en.wikipedia.org/wiki/Solar_water_heating

Large scale solar thermal systems / Victoria - A joint publication between Master Plumbers' and Mechanical Services Association of Australia and Sustainability Victoria: 2010
http://www.resourcesmart.vic.gov.au/news_and_events/business_news_4410.html




Standards

Find Australian Standards on:
'Solar hot water systems'

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