Qualification process of PV modules

March 8, 2010 - PRLog -- The first standards for solar modules are the result of research institutes’ work, especially the European Solar Test Installation (ESTI) lab in Ispra, Italy. The lab began certifying solar modules almost 20 years ago, based on their own standard, called Ispra 503. Ultimately this standard was used by the International Electrotechnical Commission (IEC) as the base for the crystalline modules standard - IEC 61215 (http://www.ee.sgs.com/ee_index/solar-testing-services-ee/sgs-photovoltaic-certification-ee.htm)  and later on the thin-film modules standard - IEC 61646 (http://www.ee.sgs.com/ee_index/solar-testing-services-ee/sgs-photovoltaic-certification-ee.htm). In accordance with these standards, modules that pass the required testing are considered able to perform well for 20 years in a moderate European climate.

Preparing modules for a tough job

The standards do not absolutely assure that modules will perform without failure for 20 years, but they definitely increase the likelihood. Crystalline and thin-film modules certification includes some rather tough sequences of tests, designed to simulate the range of climatic conditions in which solar modules will have to operate over long periods of time.

Most testing is performed in climatic chambers and includes:

•Damp-heat test – modules are exposed to temperatures of 85°C, with 85% relative humidity for 1000 hours
•Temperature cycling test – the temperature in the climatic chamber cycles back and forth between -40°C and 85°C over 200 times
•Humidity-frost test – temperatures changes in the climatic chamber as in the previous test but at an 85% relative humidity
•Hot spot test – a module is exposed to light, with several cells shaded

Crystalline modules that lose more than 5% of their power in any single test or more than 8% after a series of tests fail the testing and manufacturers need to make improvements before testing them again. Modules that show highly visible changes, such as delamination, also fail the testing. Data from various solar institutes shows that in average one third of crystalline modules and half of all thin-film modules fail the first series of testing. After identifying the cause and making improvements, the large majority of modules receive certification.

Differences for North America

As Canada and the US do not fully accept IEC 61730 for product safety, PV modules destined for these markets need to follow the local UL 1703 standard for electrical safety. For PV modules the major difference between the two standards is that UL 1703 also requires a fire test, during which a module is set on fire to see how the fire spreads based on the composition of module cells. Furthermore, certification to UL 1703 can only be performed in US or Canadian labs accredited by the Occupational Safety and Health Administration (OHSA). Harmonization of the IEC and UL electrical safety standard is a constant topic of discussion both within the industry and between governments, but there is little chance of it happening soon.

Certifying the investment

Though voluntary, module certification has become a must for PV manufacturers, as buyers want to make sure their substantial investment is worth doing and will pay off over time. The importance of certifications is reflected not only by the high number of certifications sold in Europe and the US but also by the growth of the module qualification business in Asia. Certification standards are constantly being reviewed in industry working groups to improve testing requirements that eventually lead to more efficient modules. The third edition of the crystalline modules standard will most probably be published this year and updates to the thin-film module standard are currently being discussed.

Through its testing, certification and inspection services, SGS is able to support both PV modules manufacturers and operators of solar module systems. The recently established SGS Solar Test House (http://www.ee.sgs.com/ee_index/solar-testing-services-ee/...) is fully equipped to offer crystalline and thin-film module testing and certification and can further help manufacturers in identifying the roots of module and cell failures. Through its global network, SGS offers solar module systems installation supervision and periodical inspection services.

Combining its testing and certification capacities with the experience of SGS Institut Fresenius in the semiconductor industry (http://www.ee.sgs.com/microelectronics_ee), the SGS Solar Test House can identify failures occurring in PV modules and follow their root all the way into microscopic structures.

SGS can provide services for all stages of the photovoltaic life cycle (http://www.ee.sgs.com/sgs-solar-pv-life-cicle-services-pp...).

For more information contact:

SGS Electrical and Electronics
Jörn Brembach
Business Manager Photovoltaics
SGS Germany GmbH
joern.brembach@sgs.com

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The SGS Group is the global leader and innovator in inspection, verification, testing and certification services. Founded in 1878, SGS is recognized as the global benchmark in quality and integrity. With more than 59,000 employees, SGS operates a network of over 1,000 offices and laboratories around the world.