Solar Water Heater:
Solar water heater is extremely
On a typical single-family
residence, there will generally be one or two solar collector
panels on the roof.
The panels resemble skylights,
and will be about 4 feet wide and 8 to 10 feet long.
The cold water supply is
connected to the solar storage tank. Water to be heated circulates
between the storage tank and the solar collectors.
The output from the solar
storage tank becomes the cold water connection to the conventional
gas, electric or oil water heater. When a hot tap is opened,
pre-heated water is drawn from storage into the conventional
("auxiliary") water heater.
The burner or electric element
turns on only if the temperature cannot be maintained by the solar
heater. Most properly-designed solar water heaters will supply 70
per cent or more of all the energy needed for water
The diagram shows a typical Solar
Water Heater used to supplement a conventional domestic hot
A conventional central heating pump forces water through a
coiled pipe in the solar panel where it is heated by the sun. The
heated water then flows down and through a second (lower) coil in
your hot water cylinder, referred to in the diagram as a solar
cylinder. The hot water passing through this coil heats the water
in the cylinder.
The slightly cooled water is then returned back to the solar
panel via the pump. The controller box continuously compares the
temperature in the panel against that in the hot water cylinder
(see dotted lines). It switches the pump on when the water
temperature in the panel is hotter than that in the cylinder and
switches it off when the reverse conditions apply. As long as the
water in the hot water cylinder is at the required temperature,
your existing boiler will not switch on.
The water flowing around the solar system is used to heat the
water in the tank indirectly. This means that no water in
the Solar water Heating system will come into contact
with water in your domestic hot water tank. The heat is
transferred, not the water.
Solar collectors, or panels, are designed to absorb as much of
the sun's heat as possible.
They contain water or antifreeze, which once hot usually travels
to a coil in a hot water tank and transfers the heat to the
water there - known as an 'indirect' system. In 'direct' systems,
water from the panels goes straight into the cylinder - these are
unsuitable for areas with very hard water.
In most cases solar water heating panels will not provide space
heating because there isn't sufficient sun in the winter, when you
need heating most (although on a bright, clear winter's day they
can make a welcome contribution).
However, some solar water heating systems may be designed to
heat the home in the winter and swimming pool in the summer.