Solar panel certifications: expert interview with TÜV SÜD China
Team Sinovoltaics has in the last several months been busy working on the new 2015 edition of its industry-wide unique and popular Comprehensive Guide to Solar PV Module Certifications which is due to be released by the end of January.
In the framework of the latest edition of our guide, Niclas met Alexander Krenz from TÜV SÜD in Shanghai, China to interview him about their work and the current trends, developments and challenges regarding solar panel certifications. As a preview we'll already present you here an excerpt of our interview.
About the Interviewee Alexander Krenz:
SINOVOLTAICS: Thank you for making this interview possible. As a first question, we would like to know which quality and safety certificates for photovoltaic modules can TÜV SÜD award?
Alexander Krenz: You are welcome. The most common standards among the PV industry are the safety and performance standards for typical PV modules. TÜV SÜD provides the testing and certification services to support PV module manufactures to comply with these standards
SINOVOLTAICS: Compared to other certification bodies, what is TÜV SÜD's particular strength and specialty?
Alexander Krenz: TÜV SÜD is in a leading position amongst other market players. We cover a wider spectrum of testing and certification services for a variety of PV products and applications. Compared to others we are faster and more flexible when it comes to product qualification, safety, and global market access solutions.
"The term “quality” is too generic and often misused. Reliability for specific climates is neither defined nor covered by the existing IEC standards"
SINOVOLTAICS: In your eyes, what is the actual value of a PV module certification?
Alexander Krenz: Definitely, the current PV module performance and safety qualification remains as the minimum criteria for “quality” in the industry. Here we have mainly the IEC 61215/ 61646 as performance and type approval in combination with IEC 61730-1/-2 for safety compliance. However, the term “quality” is too generic and often misused. Reliability for specific climates is neither defined nor covered by the existing IEC standards.
SINOVOLTAICS: What is the standard procedure of PV module certification at TÜV SÜD? How long does it take on average?
Alexander Krenz: On average, the certification for design and type approval with safety for a PV module type takes about 3.5 months. The certification procedure is complex and often misunderstood by outsiders. Normally it begins with the definition of the test and certification scope. Basically the outline for specific market or country access needs. The next step is the elaboration of a test plan. Afterwards we collect the amount of samples needed from the manufacturer or they submit the requested amount directly. Once we have the samples the actual testing to the standards can start. After positive testing, we’ll schedule and perform a factory inspection. Finally, we will issue the certificates after positive testing and positive factory inspection.
SINOVOLTAICS: Having a module correctly certified to a standard is one thing, but what do certifications actually tell about the output quality of a manufacturer?
Alexander Krenz: Well, as mentioned earlier it represents the minimum criteria of product conformity and includes type testing combined with periodic factory inspections (production surveillance audits). This means the manufacturers’ production facility(ies) will be inspected annually and the production is monitored. By having regular on-site visits, we are able to verify that a stable production output criteria is met and provide recommendations to enhance it. Deviations will lead to non-conformities which will have to be corrected.
SINOVOLTAICS: Once a manufacturer has obtained the required certificates, when it comes to many quality standards, there are only rare quality verification follow ups. Would you consider this as a loophole?
Alexander Krenz: Yes and no. Periodic factory inspections or production surveillance audits performed by the certification body are obligated and this constitutes the basis for the certificates issued by that certification body (thus bearing their particular mark/logo).
Buyers however often request additional quality insurance measures at the manufacturer’s production site such as: specific factory inspection(s); during production inspections; pre-shipment inspection; container loading supervision
SINOVOLTAICS: But, with no independent, continuous production supervision in place, how can worried buyers be sure about the quality of their PV modules?
Alexander Krenz: Big buyers request additional and specific audits performed at the manufacturer on behalf of the buyer: specific factory inspection(s); during production inspections; pre-shipment inspection; container loading supervision
"We know that micro cracks can, but not necessarily will, lead to critical damages over time. Here we don’t only talk about a certain acceptable performance degradation ratio, but actual safety risks, which evolve over time"
SINOVOLTAICS: What can you say about the severity of micro cracks and potential problems they can lead to?
Alexander Krenz: We know that micro cracks can, but not necessarily will, lead to critical damages over time. Here we don’t only talk about a certain acceptable performance degradation ratio, but actual safety risks, which evolve over time. This can result in thermal and fire hazards also caused by arching. Especially with the recent popular PV module types qualified for a max. system voltage of 1500V.
SINOVOLTAICS: What is the best way for comparison testing of modules in terms of performance and long-term functionality?
Alexander Krenz: This relates indirectly to a “good quality” module and the question how “reliable” will it be? To find the right answers I would recommend to perform the comparison between
- a) Simulated and prolonged stress testing in the lab in combination with
- b) Long term out-door field testing under real environmental conditions
The collection of data will provide all possible degradation patterns with regard to safety and performance aspects. TÜV SÜD has elaborated a specific test sequence like the “Thresher test” to address this issues. We also have a new outdoor test facility in Dunhunag/Gansu China for long term outdoor field testing under real environmental conditions.