HOW

does a SOLAR POWER SYSTEM work?

Solar photovoltaic (PV) panels are installed on top of the roof.  Each panel consists of solar (photovoltaic) cells.  These cells absorb sunlight during the day which results in an electric current (DC - direct current).  Our homes are powered with AC (alternating current) electricity.  Inverters are used to change the generated DC electricity to AC electricity which runs through your home's DB (distribution board).  It works exactly the same way as the electrical power generated through the grid by Eskom.  The solar power system remains connected to Eskom which supplements any shortfalls.  Batteries can be installed as part of the solar power system to assist in powering your home at night, on cloudy and rainy days, and during loadshedding when there is not enough sunlight to generate DC electricity.  "Net metering" occurs when consumers are compensated for producing more solar power than what they need and the power is sent back into the grid.

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does a SOLAR WATER HEATING SYSTEM work?

A solar thermal collector is installed on top of the roof.  The collector absorbs sunlight during the day which results in heat.  The heat is passed to a geyser by means of the "thermo siphon effect" or a 12V DC solar pump with a 10W PV panel.  A Geyserwise TSE or Geyserwise Max with a 7A 12V Battery can be installed which functions as a timer.  A mixing valve is installed to prevent scalding as a result of very hot water.  An air release valve is installed to release excess air to maximise system performance.  

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Two types of collectors are available:

• Evacuated tube collector:  The collector consists of an anodized aluminium frame and manifold, and solar vacuum tubes.  Each vacuum tube consists of two glass tubes manufactured from borosilicate glass.  The outer glass tube is transparent allowing light rays to pass through it with minimum reflection.  The inner glass tube is coated with a solar special selective coating (AI-N/A1) which provides excellent solar radiation absorption.  The top of the two vacuum tubes are fused together and the air is extracted, which forms a vacuum and is key to the efficiency of the vacuum tubes.  To maintain the vacuum between the two vacuum tubes, a barium getter is used.  The barium layer also provides a clear visual indication of the vacuum status.  The silver coating will turn white if the vacuum is ever lost.  Inside each vacuum tube is a copper heat pipe.  The top part of each heat pipe is connected to a copper heat exchanger (manifold).  The heat energy of the hot vapour inside the vacuum tubes is transferred to the water flowing through the manifold to and from the geyser.

• Flat plate collector:  The collector consists of an absorbing plate with several parallel copper pipes.  Water runs to and from the geyser through these pipes.  As sunlight heats the absorbing plate, heat is transferred to the water inside the pipes.  To minimise heat loss, the bottom and sides of the collector are insulated.​

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Two types of systems are available:

• Thermo siphon system:  Both the geyser and solar thermal collector are installed outside on top of the roof.  The geyser is installed higher than the solar thermal collector.  In case of a flat roof, a flat roof geyser stand is installed.  Because of the "thermo siphon effect", no circulation pump is needed. 

• Split pumped system (including conversion of existing electrical geyser):  Only the solar thermal collector is installed outside on top of the roof.  The geyser is installed inside the roof or against a wall, lower than the solar thermal collector.  In case of a flat roof, brackets are used to install the solar thermal collector at an angle.  A pump is needed to circulate cold water from the geyser to the collector and hot water from the collector back to the geyser.  The pump can be either a 12V DC solar pump or a 220W AC electrical pump.

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Two types of configurations are available:

• Direct:  In an evacuated tube collector, water circulates from the geyser through the collector's manifold and back to the geyser.  In a flat plate collector, water circulates from the geyser through several parallel copper pipes inside the collector and back to the geyser.  Water inside the geyser is heated directly by solar energy. 

• Indirect:  Glycol (antifreeze) circulates through copper pipes inside an indirect solar geyser through several parallel copper pipes inside a flat plate collector (where it is heated by solar energy) back through copper pipes inside the geyser.  Water inside the geyser is heated indirectly by solar energy.

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does a HEAT PUMP work?​

Heat is transferred from the outside air into the water inside the geyser by means of a fluid ("refrigerant").  The temperature of the refrigerant is lower than that of the ambient air.  As the refrigerant passes through the evaporator, heat is exchanged as the refrigerant is heated and the air cooled.  Heat transfer is improved by a fan which increases the evaporator's air flow rate.  The refrigerant starts to boil and turns into a gas.  The gas is compressed by a compressor until it reaches a temperature higher than that of the water inside the geyser.  The gas is then pumped into a condenser which transfers the energy from the warm gas into the water.  Condensation takes place and the gas becomes a fluid ("refrigerant") again.  The refrigerant passes through an expansion valve and its temperature is reduced to a temperature lower than that of the ambient air.  The process then repeats itself.