SELFA GE S.A. has extensive experience as regards the technology of producing silicon PV modules resulting from long-standing cooperation with scientific institutions and specialists from all over Europe. Our PV modules are manufactured on an automated production line using latest technological solutions, which guarantees high quality and repeatability of processes.
Silicon PV module production technology
The main raw material for producing both mono- and polycrystalline PV cells is high-purity crystalline silicon (c-Si).
The first stage of the production process comprises chemical removal of impurities resulting from the process of cutting a silicon block into thin panels (thickness usually from 160 to 220 µm). Next, silicon panels are textured to enlarge the surface active to sunlight.
Phosphorus diffusion creates the p-n bond in a cell. The doped p bond of the cell is heated in an oven to the phosphorus gaseous state temperature. Phosphorus atoms diffuse to silicon and create an n type dope on its surface.
The active cell side is covered with an anti-reflecting coat increasing sunlight absorption and improving electric parameters of the cell. The anti-reflective coat is created by deposition of silicon nitride on the surface.
During the next stage, the cell surface is covered with a metal conducive mesh using the screen printing process. This mesh is to collect electric charges from the whole cell surface. On the bottom and surface part of the cell, thin busbars are created (usually 2 or 3) to which connection ribbons are soldered during the module production process.
Ready photocells are next classified according to their electric and optical properties, sorted and prepared for PV module production.
PV module production technology
During normal operation in weather conditions, a PV module is often subjected to low and high temperatures, rain, snow, etc. Thus it is very important that all electric elements are permanently and tightly isolated from external impacts.
The first stage of PV module production process is connecting photocells in series using copper connecting ribbons. During the soldering process, automatic visual inspections are performed to prevent damaged cells from being installed in modules. Connected cells are laid on hardened glass covered with the EVA film and electrically connected with one another.
After connecting a full “matrix” of cells, other layers of EVA film and electro-insulating film are laid to protect the module against external conditions. A module prepared in this manner is laminated in 150°C and becomes fully tight.
These laminates are inserted in aluminium frames and a junction box with wires is connected to the bottom surface of a module.
Ready-made PV modules are subject to inspection on sunlight simulators in standard testing conditions (STC: 1000W/m2, 25°C, AM1.5) when electric parameters, i.e. maximum power (Wp), short-circuit current (Isc), open-circuit voltage (Voc), etc., are defined.
PV modules manufactured by SELFA GE S.A. comply with all European standards concerning design, inspection, testing and safety of PV modules. Conformance to standards (IEC 61215[e.2], IEC 61730-1 and IEC 61730-2) is confirmed by a certificate issued by the German Institute of Research and Certification (VDE).