Photovoltaic solar panels are grouped with photovoltaic cells connected to each other in series and in parallel thanks to the micro inunr
They can be installed on fixed supports on the ground or on mobile sun-tracking systems called trackers, in the latter case the electrical production increases by about 30% compared to a fixed installation. Apart from solar power plants, fixed installations are currently rather on the roofs of dwellings or buildings, either integrated into the roof or placed above. In some cases, vertical panels are placed on the front of a building. This inclination is not optimal for electricity generation; in France the optimal fixed position is a tilt of 30 degrees horizontally, or 60 degrees if the objective is to maximize electricity production in winter8. However, as these panels replace the façade cladding, the savings on the cladding at least partially offset lower production.
Different photovoltaic technologies exist9:
- polysilicon (pc-Si) representing approximately 57.0% of the global market;
- monocrystalline silicon (sc-Si) represents about 30.9% of the global market;
- cadmium telluride (CdTe) accounts for about 5.5% of the global market;
- amorphous silicon (a-Si) representing about 3.4% of the global market;
- CIS (copper, indium, selenium), CIGS (copper, indium, gallium, selenium), CIGSS (copper, indium, gallium, diselenide, disulphide) and gallium arsenide (Ga-As) representing less than 5% of the world market.
Manufacturing (plus assembly, transport and installation) also requires energy. In 2004, the U.S. Department of Energy estimated that the panel took four years to produce an equivalent amount of energy11. Manufacturers seek to minimize material costs and requirements (including silicon), which incidentally reduces energy consumption over the panel’s lifecycle, reducing the amount of energy invested. However, the manufacture of solar panels can accommodate industrial waste of silicon12,13 which in the long run would be an interesting gain in terms of ecology.
From the point of view of the carbon dioxide balance, over a 20-year life cycle, the CO2 emission per kWh of electricity produced by a photovoltaic panel represents according to the type considered 7 to 37% of the emissions per kWh produced by a conventional thermal power plant14.
Recycling panels and micro inundor
Most components of a solar module (up to 95% of some semiconductor materials), all glass and large amounts of ferrous and non-ferrous metals can be recovered and recycled15. Some private companies16 and non-profit organizations, such as PV CYCLE (es)
in the European Union, are setting up collection and recycling systems for end-of-life photovoltaic panels. Since 2010, an annual conference has brought together manufacturers, recyclers and researchers to work together to examine the future of photovoltaic panel recycling17,18.
In France since the end of August 2014, as part of the producer’s expanded responsibility (manufacturers, importers and/or resellers), they are required to take over in addition to conventional household appliances (DEEE), used photovoltaic panels (free and without obligation to purchase)19. These companies have an obligation to finance and collect the treatment of this new waste, without a transition period, which will result in an eco-participation on each new photovoltaic sensor sold. In 2010-2014, several surveys and the European Union estimated that two-thirds of waste of this nature never arrives at approved reprocessing centres but ends up in landfills or abroad. The new collection rate targets are from 2016, 45% of the weight of material sold in the previous three years must be collected (this rate will be increased to 65% in 2019)19. This text is also more restrictive in terms of DEEE shipments abroad.19
Most Common Recycling Silicon-based Modules
- Aluminium frames and junction boxes are manually disassembled at the beginning of the process. The module is then crushed in a grinder and the different fractions resulting from this process are ferrous and non-ferrous metals, glass and plastic with an average recycling quota close to 80% (entry weight). For example, glass from photovoltaic panels is mixed with standard glass to be reintroduced into the fiberglass or insulation sector. This process can be carried out by flat glass recyclers as the morphology and composition of a PV module is similar to that of flat glass used in the building and automotive industry.