'Photovoltaic (PV) solar electricity generation' and 'solar geysers or solar water heating' involve two fundamentally different technologies, but both rely on the conversion of energy carried by solar radiation (sunlight).
On a sunny day in Cape Town, sunlight delivers a powerful stream of energy to the tune of 1 kW per square meter.
'Photovoltaic solar electricity generation' involves the one step conversion of this radiation energy to electrical energy.
The technology required is based on the physical properties of semi-conductor materials like silicon and others. Here the sun's rays strike the PV cells in the PV solar panels and are converted into electrical energy.
The conversion efficiency, i.e. the amount of energy that can be 'harvested' from the sun's radiation varies depending on the technology and materials used.
Recent developments with Graphene point to a possible future 60% conversion efficiency.
'Solar geysers' on the other hand involve a one step conversion from radiation energy to thermal heat.
The solar rays heat the water or transfer liquid directly in the solar collection tubes on the roof.
The heated water is then circulated into the storage device or solar geyser.
The technologies vary from large scale solar power plants to household sized solar water heaters where radiation is collected and absorbed resulting in the generation of heat.
The conversion efficiency here lies much higher at 70%.
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