Step by step production of crystalline solar panels
10. 4. 2025
Solar energy is central to the transition to sustainable energy. Crystalline solar modules dominate the market because their efficiency and durability make them the preferred choice in photovoltaics. In order to produce them on a large scale and cost-effectively, automated production processes are used.
Crystalline silicon modules are the most widely used technology in photovoltaics. They consist of several solar cells that are made of silicon wafers. The wafer contains doped silicon, which can create electrical charge separation by the targeted addition of foreign atoms.
Thin metal contacts - called busbars and fingers - conduct the current. The fine metal fingers collect the current across the cell surface and conduct it to the busbars, which serve as a bus for further power transfer. A solar module consists of several solar cells. To protect the sensitive cells from mechanical and weather effects, they are sandwiched between several layers.
A glass plate on the front provides stability, while a plastic film (usually EVA = ethylene vinyl acetate) serves as the encapsulation material. The back side consists of another plastic film or a second layer of glass, to which an interconnection box is also attached to transfer the generated DC current. An aluminium frame encloses the module and facilitates installation.
Step-by-step manufacturing of the solar module
The production of silicon wafers is a highly specialised process usually carried out by high-tech companies. The actual production of the solar modules starts with the finished solar cells, which are already doped and coated with an anti-reflective layer.
Step 1: Connecting the solar cells - the stringing process
The first step in the production of solar modules is to connect the individual solar cells. This process is called stringing: the cells are connected via busbars with thin copper strips (ribbons). The cells are arranged in rows - called strings.
To avoid cracks and microcracks in the sensitive silicon cells, maximum precision is required. The soldering process must be optimized to minimize mechanical and thermal stresses.
Step 2: Cutting and Layer Placement - Layering Process
Once all the layers of the solar module - clo, EVA film, strings and back sheet - have been cut to size, they are precisely laid on top of each other in the next step. This process is called layup/layup: automatic positioning is carried out with an accuracy of ±0.1 mm.
Step 3: Lamination
After positioning, the individual layers are joined together to form a stable and durable unit - called lamination. The module is heated in a vacuum bag or autoclave, usually to a temperature of approximately 140 °C, using either vacuum or overpressure (up to 10 bar).
During this process, the previously milky EVA film is polymerised into a clear, three-dimensionally cross-linked plastic layer. This firmly bonds the solar cells to the glass sheet and the back film.
Step 4: Edge banding and frame
After lamination, the module is ready for final use. First, the edges are trimmed to remove any overhanging material - especially the remnants of the EVA film and back sheet. Then the junction box is installed.
In the last step, the module is fitted with an aluminium frame to ensure mechanical stability and facilitate assembly. The frame is attached either with silicone or with special adhesive tape.
Step 5: Quality control and classification
Before the solar module leaves production, it is tested for performance and safety.
A solar simulator measures the electrical characteristics, while electroluminescence and insulation tests reveal defects or flaws in the material. Finally, the modules are graded according to power level before packaging and shipping.