Not long after China imposed restrictions on travel between provinces, problems in PV module factories all over the country began to accumulate. Let’s start with questions about personnel.

Staff from provinces affected by the pandemic who decided to return to factories after Chinese New Year on January 25 were not permitted to do so because a 15-day quarantine period had been implemented.

Owing to travel restrictions, those who were able to return were in several cases many days late. Some factories had temporary workers hired to fill the gap. Nevertheless, adequate preparation was missing for most of those occasions. In the following weeks, the result was an abnormally high rate of defects on production lines.


Delivery issues were immediate as a result of the travel restrictions and shortage of staff. Trucks were queuing at checkpoints while drivers had their temperatures measured and roadblock-induced traffic jams were a normal occurrence in February. Consequently, the supply chain was interrupted and the stored reserve materials were depleted before the beginning of the new year holiday. Manufacturers will not be returning to pre-crisis levels of production until the end of March.

The effect of non-existent, or at best negligible, development on the other side of the world was of course immediate. For some developers, the lack of module supply had a devastating impact.

In Germany, for example, where fixed tariffs are bound to strict grid link dates, the long-term economic sustainability of the projects has been put at serious risk. That situation prompted several developers and engineering, procurement and construction companies (EPCs) to accept older modules or panels made by manufacturers of original equipment (OEM). As a result, contract provisions for the provision of modules relating to independent quality control have been removed. For instance, modules which did not meet agreed frame dimensions or cable lengths appropriate for tracker systems may be accepted.


Another example was a developer forced to accept panels from three OEMs which resulted in 12 bills of material (BOMs), hampering the traceability of materials and any assessment of the processes involved in the development. Some of the BOM combinations in that instance were not specified in the data forms for the certification construction. The variety of BOMs may explain why some of the modules showed a high susceptibility to potential induced degradation (PID) or light and elevated temperature-induced degradation (LeTID), or why post-stabilization degradation (light-induced degradation) varied widely.

To complicate matters further, manufacturers who denied access to factories for our engineers, despite no COVID-19-related restrictions being present in the provinces concerned, had to deal in a few cases with a lack of cooperation. However, at the other extreme, some manufacturers facilitated our transit by offering official letters of invitation via checkpoints. The situation has complicated our day-to-day job considerably and has become an obstacle course for enforcing control measures in record time.

Those measures included remote production control via video cameras allocated to factory workers with little knowledge of production lines. In a severe case where external auditors were unable to gain entry to the facility, such a solution would be seen as a necessary evil. On the other hand, in cases where modules were already produced and monitoring of output was no longer possible, product flash lists were used to pick samples to be sent to our Suzhou laboratory.

Module samples included modules of the same class with low, medium and high strength, from different batches, and with different patterns of failure visible under electroluminescence.

What is it we can learn from all this? First, during the crisis, quality control was critical in avoiding changes in material selection and manufacturing processes not covered by contractual arrangements. Secondly, fast decision-making on vital activities; the expertise we have acquired from factories over the last nine years; and the resilience shown by our customers have allowed us to perform effectively in a unique situation.

Having said that, a contractual arrangement between supplier and customer that speeds up the execution of some of our key quality assurance guidelines may have prevented some of the problems some manufacturers have faced.

Last but not least, as a protective measure for future pandemics, module supply agreements will cover the following points: thorough elaboration of the pandemic principle as a force majeure; day and night agreement production oversight to improve control over non-approved products without notice; and clear indication that manufacturers can not refuse access to auditors.

Source – here