SOLON Solar Modules Achieve Excellent Results in PID Test

Potential induced degradation (PID) is one of the main causes if a solar power plant's performance diminishes over the course of its service life.

Several solar manufacturers have now partnered up with renowned German testing institutes to launch a new initiative to prepare standard module tests for this phenomenon, which has been the subject of a large number of recent investigations. The objective is to enable consumers to recognize PID-resistant modules.

Solar energy companies SOLON, Schott Solar and Q-Cells, along with the Fraunhofer Institute for Solar Energy Systems ISE, the Photovoltaik-Institut Berlin (PI-Berlin), TÜV Rheinland and the VDE, the Association for Electrical, Electronic & Information Technologies, have developed a test for this purpose, which is easy to conduct and allows a solar module's PID resistance to be tested. Electrical leakage current, which can flow between a solar power plant's components, causes the power loss through PID. Instead of producing electricity, the cells short-circuit themselves.

During the test, PID-stabilized series production modules from the participating companies as well as modules from other brand manufacturers were subjected to the maximum system voltage of 1,000 V at a temperature of 25 degrees for seven days. To achieve exact comparative values, all modules were grounded and covered with aluminium foil or a continuous water film. The relevance of the test conditions was controlled using prepared test modules that SOLON had previously developed for all testing institutes. If a module lost less than five percent of its power during the test, it was considered PID-resistant within this context.

SOLON modules completed this test, which was conducted in several testing laboratories independently of each other, with a power loss below 5% and proved, as expected, to be PID-resistant. The modules of the other two participating companies also passed the test. In contrast, several of the other brand products exhibited power losses of more than 50%. "As innovation leaders, we have intensively examined PID and ensure that our customers are only provided with tested quality," said Dr. Lars Podlowski, Chief Technology Officer of SOLON. The company is performing research in long-term studies using its own testing facilities to determine how PID develops under various climatic conditions and how the solar power plants affected by PID can be regenerated by grounding or other concepts.

The PID effect can generally occur in crystalline and thin-film modules and intensifies in larger-scale power plants and with rising system voltages. Depending on the technology, however, it is reversible. PID can be prevented at the plant level if the plant is grounded, or when inverters are used that do not generate any harmful voltages. However, it is more cost-effective to prevent PID at the module or cell level.

The developed test procedure is to be extended. The objective is to implement a more advanced PID proof test in the IEC standard.



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