What is the difference between “photovoltaic solar generated electricity” and “solar thermal heating”?

 

“Photovoltaic solar electricity generation” and “solar thermal heating” involve two fundamentally different technologies, but both rely on the conversion of energy carried by solar radiation (sun light).
On a sunny day, sun light 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 radiation energy to electrical energy. The technology required is based on the physical properties of semi-conductor materials like silicon and others.
    The conversion efficiency is approximately 17%, i.e. the amount of energy that can be “harvested” from the sun’s radiation is only about 17% of the energy carried by the radiation.
  • “Solar thermal heating” on the other hand involves a one step conversion from radiation energy to thermal heat. The technologies vary from large scale thermal power plants to household sized Solar Water Heaters and Solar Stoves where radiation is collected and absorbed resulting in the generation of heat.
    The conversion efficiency here lies much higher at 70%. Hence it follows that it is extremely inefficient to heat with solar generated electricity.

 


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