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Solar Water heating
Thermosiphon system
Thermosiphon solar geysers work on the thermal principle of circulation.  The water
storage vessel (geyser) will be at a point higher than that of the solar collector.  The
coldest water will always be at the lowest point in the system (solar panel/collector),
whilst the warmest water will be at the highest position in the system (top of geyser). 
This will cause a continuous circulation of water and cause an effective heating
Split pump system
Split pump solar geysers are units where the sorage vessel (geyser) is placed at a point
lower than that of the solar collector.  Because the warmest water will automatically lie in
the collector, thermal principles will not apply, and water needs to be artificially circulated
between the solar collector (panel) and geyser tank.  These systems tend to be more
aestethically pleasing, as only the collector will be visible on the roof, and the storage
tank can be placed inside the roof space or mounted on a wall etc.
Flat plate solar geysers
Flat plate solar panels appear like a glass box on the roof.  The inside of the panel has an
absorber plate which water or anti-freeze substance circulates through in order for heat
from the sun to be transferred to the water/anti-freeze.  In any area where frost occurs
this system needs to be installed as an indirect system (anti-freeze/glycol) which reduces
efficiency and also increases maintenance costs.  These systems are not advised to be
used in conjunction with existing electrical geysers in a retrofit set-up.
Evacuated tube solar geysers
Evacuated tube solar panels has seperate tubes incorporated into a single
frame/manifold set-up.  These tubes are frost resistant and also provides good efficiency,
as the collector is not influenced by ambient temperature but mostly rely on radiation
from the sun.  These collectors can be used to heat water directly as there is no risk for
freezing, even in sub-zero temperatures.  These systems are ideal for retrofitting existing
electrical geysers and also preffered for new solar geyser installations.
Solar Craft Pretoria - Providers of sustainable and green solutions for the future
Solar Water Heating