SELFA GE S.A. has extensive experience in silicon photovoltaic module production technology, supported by long-standing cooperation with scientific institutions and specialists from across Europe.

We are constantly engaged in research to improve the performance, quality and durability of our products. This was one of the reasons for the establishment of the Selfa GE S.A. Research and Development Centre in December 2018 – watch the video

Our photovoltaic modules are produced on an automated production line, using the latest technology, thus guaranteeing high quality and repeatability of the process.

Video - Production process of photovoltaic modules - Selfa

Technology for the production of silicon photovoltaic cells

The main raw material for the production of both mono- and polycrystalline photovoltaic cells is high purity crystalline silicon (c-Si).

The first step in the cell manufacturing process is to chemically remove contaminants from the process of cutting a silicon block into thin plates (typically 180–220 µm thick). The silicon plates are then textured to increase their active surface sensitive to solar radiation.
A p-n junction is formed in the cell by the diffusion of phosphorus. The doped p junction of the cell is heated in an oven under the gaseous phase of phosphorus. Phosphorus atoms diffuse to silicon and form an n-type dope on its surface.

An anti-reflective coating is applied on the active side of the cell to increase the absorption of solar radiation and improve the electrical parameters of the cell. The anti-reflective coating is formed by deposition of silicon nitride on the surface.

In the next step, a metal conducting grid is applied to the cell surface using the screen printing method. This grid is designed to collect electrical loads from the entire surface of the cell. Thin bus bars (usually 5) are also formed at the bottom and top of the cell, to which connection strips will be soldered later in the manufacture of the module.

The finished photovoltaic cells are then classified according to electrical and optical characteristics, sorted and prepared for the production of photovoltaic modules

Photovoltaic module production technology

Photo: Photovoltaic module construction

During normal outdoor operation, the photovoltaic module is often exposed to both low and high temperatures, rain, snow, etc. Therefore, it is very important that all electrical components are permanently, hermetically isolated from external factors.

The first stage in the production of photovoltaic modules is the serial connection of the photovoltaic cells by means of copper connection strips. During the soldering process, automatic visual inspection is carried out to prevent damaged cells from being placed in the module. The connected cells are placed on a tempered glass covered with EVA film and then electrically bonded to each other.

Photo: Solar module production technology at SELFA GE S.A.

When the full "matrix" of cells is assembled, subsequent EVA film and electroinsulating film layers are applied to protect the module against external factors. The module is then subjected to lamination at approximately 150°C and is completely hermetically sealed.

The laminates are mounted in aluminium frames and a junction box with wires is mounted to the bottom surface of the module.

The finished photovoltaic modules undergo a check in a solar simulator under standard test conditions (STC: 1000 W/m², 25°C, AM1.5), where electrical parameters are determined, such as: maximum power (Wp), short circuit current (Isc), open circuit voltage (VOC).

The photovoltaic modules produced by SELFA GE S.A. meet all applicable European standards for the design, inspection, testing and safety of solar modules. Compliance with standards is certified by the German VDE Testing and Certification Institute and KIWA Cermet Italia.