STS News

May 2019

STS Releases Addendum to STS-STD-PVM1 for Bi-Facial PV Modules To Support Module Buyers Better Secure Quality at Pre-Dispatch Inspection

STS, the industry leader in PV modules quality control, announces today the release of its Addendum to STS-STD-PVM12018© for Approval of PV Modules Manufacturing and Dispatch. This new industry-level standard is the result of an 8-months work on bi-facial PV modules, that included technical studies, consultations, manufacturing witness and lab testing in collaboration with laboratories and manufacturers.

The Addendum, referenced STS-STD-PVM1-22018© AA1, complements the initial standard released by STS in 2018 and adds requirements specific to bi-facial modules, among which

– production control requirements to test rear side modules performance during mass-production; – adjustment of criteria for manufacturers’ quality control processes to include PO and POE materials;

– electrical measurement method to rear side of the PV modules;

– components placement requirements.

About STS-STD-PVM12018©

This Standard is unique in the way it finally enables PV modules suppliers and buyers to apply specific, measurable and objective requirements during production and dispatch to qualify PV modules.

To date, STS-STD-PVM12018© has been applied to more than 1GWp of PV modules manufacturing worldwide.

The goal of the Standard is to draw the requirements for manufacturing, dispatch, inspection undertaken at manufacturing premises, and related testing activities taking place at ISO17025 accredited laboratories. It does not aim at replacing but instead to complement the established IEC and UL standards, taking into account the reality of PV modules conditions during mass- production.

STS-STD-PVM12018© has been developed based on existing standards, known limitations, extensive internal research, extended reliability testing and technical consultation with manufacturers, installers and other industry stakeholders involved.

STS manufacturing witness experience of more than 5GWp was used as one critical input baseline in addressing the reliability and practicality of the Standard, to secure both quality and performance for Buyers while addressing challenges faced by manufacturers.

Thibaut Lemoine, Vice-President of Operations at STS further explains:

“While IEC and UL standards are inevitable references to qualify PV modules design in terms of safety and performance, buyers and lenders are confronted with the challenge of validating the quality of modules coming out of the production line.

Manufacturers had to define their own control methods and acceptance criteria to address the loopholes of these international standards, sometimes without solid ground to guarantee products quality and performance, leaving the Buyers helpless when faced with subjective criteria varying from a factory to another, and unable to guarantee return on their investment.

For 8 years, STS has been working on addressing this situation, source of conflicts between Buyers and Manufacturers and leading to delays and higher costs in the projects.

Through our research, deployment of SMART requirements at factories, feedback from producers, reliability tests analysis, we are now able to bridge this gap and offer consensus to all stakeholders. We have developed this Standard with the spirit that it must be practical and easy to execute, to serve a quality-effective yet economic purpose. With STS-STD-PVM12018©, we finally bring the industry standard that was critically needed by the PV community to drastically reduce risks of underperforming PV modules and ensure financial returns of solar assets.”

STS team will provide further introduction of STS-STD-PVM12018© AA1 during Intersolar Munich in Shanghai from May 15 to 16. Appointments can be made in advance by contacting Mr. Javie Yin at

STS-STD-PVM12018© AA1 can be ordered via STS website ( or by contacting STS team at