Manufacturing technique and return on energy investment (source Wikipedia )
Silicon is currently the most used material to manufacture photovoltaic cells available at an industrial level. Various sand treatments make it possible to purify the silicon which is then heated and reduced in an oven. The product obtained is a so-called metallurgical silicon, only 98% pure. This silicon is then chemically purified and results in electronic grade silicon which is in liquid form. Subsequently, this pure silicon will be enriched in 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 for about 2 to 3 years depending on its technology to produce the energy that was necessary for its manufacture (energetic return of the module)