How are photovoltaic modules produced and what are the methods for optimization of this process?
Understanding the manufacturing process helps to understand the points that are fundamental for the production.
All operations are performed by automatic machines dedicated to optimize the single production phases that transform the raw material into finished product.
1. Preparation of the raw material
First, the glass is being cleaned, then rolls of encapsulant and backsheet material are being cut using cutting machines.
Solar cells are placed in solar stringer that interconnects the cells in a series by soldering a coated copper wire (ribbon) on the bus bar of a solar cell. Creating this string is one of the most delicate operations in the whole process. It’s really important to check the soldering quality.
3. Placing cells on the glass
The strings of solar cells can be now placed on the previously prepared glass with encapsulant layer by lay-up machine that also performs quality controls of the product.
4. Bussing soldering
In order to create an electrical circuit, a bus ribbon with larger thickness is used. In a standard pv production line this phase is performed manually.
5. Pre-lamination preparation
After finishing electrical circuit between all strings of cells, a second layer of encapsulation material is being applied followed by a foil of insulating back sheet. Ribbon will be connected in a successive step with the junction box. Electrical and electroluminescence tests are performed in order to check there are no short circuits or broken photovoltaic cells inside the module.
Lamination process consists of transforming a multi-layer sandwich into one unit. Laminators work at a high vaccum for a certain time and at a certain temperature. The extraction of the air guarantees the quality and durability of the product.
Production lines with a high throughput often have cooling systems installed after the laminator to permit a quick process without waiting times;
The procedure is based on trimming the surplus material of the encapsulant and back sheet left around the glass. Then the frame is applied with tape applied directly to the laminate.
8. Application of the junction box
The j-box is attached with a suitable silicone or glue on the back sheet of the panel and by making the electrical connection between the bus ribbon prepared before the lamination and the cables of the junction box. After finishing this operation the module is cleaned.
9. Final test
At the end of the assembly phases the pv module is being is being controlled and tested. This part is very important due to electrical output measurement done by sun simulator is able to reproduce.