One inspection project out of three has at least one non-conformity in relation with sub-components. In particular, the cell is a very critical sub-component that is sometimes not controlled to the level expected by our clients. Even a thorough IQC (incoming quality control) may not be enough to reach a comfortable level of assurance, especially when the module manufacturer sources cells from an external supplier. It comes therefore at no surprise that our clients are engaging STS to inspect the cell quality directly at the cell manufacturing lines.
For cell inspection, we recommend verification of manufacturing records instead of production supervision for the reason that the cells factories are much more automated than PV modules factories. Manufacturing cells requires less manual work and is therefore less prone to operator errors. The production processes (IPQC records) and the materials used for production (IQC records) require more attention to make sure that the processes are under control and the materials are of adequate quality.
A typical scope therefore includes both manufacturing records verification as well as a thorough pre-shipment inspection. Depending on the shipping terms, loading supervision may also be required. Last but not least, inspection at cell manufacturing significantly increases the visibility of the supply chain when traceability is a requirement.