Manufacturing technique and return on energy investment (source Wikipedia )
Silicon is currently the most used material for manufacturing photovoltaic cells available on an industrial level. Various treatments of the sand make it possible to purify the silicon which is then heated and reduced in an oven. The product obtained is a metallurgical silicon, 98% pure only. This silicon is then chemically purified and results in electronic grade silicon which is in liquid form. Subsequently, this pure silicon will be enriched with doping elements (P, As, Sb or B) during the doping step, in order to be able to transform it into a P or N type semiconductor.
The production of photovoltaic cells requires energy, and it is estimated that a photovoltaic cell must operate approximately 2 to 3 years according to its technology to produce the energy which was necessary for its manufacture (energetic return of the module)