After two years of practical experience with the PV+Test testing program, TU?V Rheinland and Solarpraxis have decided to intensify the test in several areas. On the one hand, this will help subject the numerous PV modules available on the market to even greater scrutiny, and make it easier to differentiate the modules from one another.
What is new, for example, is testing and evaluation of the initial degradation of the modules, also referred to as light-induced degradation (LID). This effect has been known about for a long time in the case of thin film modules, but it can also occur with crystalline modules. The manufacturers of crystalline modules do not always take this LID effect into consideration when it comes to performance specifications on the nameplate. Thus if a manufacturer fails to consider initial degradation when it comes to power sorting, then this would result in point deductions for PV+Test 2.0 evaluations in the future.
The climatic chamber tests also contain more stringent test conditions. For example, an extended thermal cycling test in which the modules have to twice survive 200 cycles between -40 and +85°C. In the likewise extended damp heat test the modules now have to twice survive 1,000 hours at 85°C and 85% relative humidity. Initially with the old test the electroluminescence (EL) tests were performed only at entry and after the thermal cycling test. This testing method is now used for damage detection after all load tests and is incorporated into the undervaluation. In particular the change in the EL image is evaluated here against the initial entry image. A new test for potential-induced degradation, PID for short, with plus and/or minus 1,000 volts is also new to the portfolio of aging tests.
Several changes have also been carried out with regard to the tests on temperature fluctuation and low-light performance. In the first round of testing the temperature coefficient and low-light performance were for the most part still considered separately from each other. In the new PV+Test 2.0 both values are evaluated in a so-called matrix measurement, which follows the IEC standard 61853 Part 1 and provides for a much more differentiated view of the performance of the module at fluctuating temperatures and light conditions, thus allowing conclusions with regard to the energy yield. Evaluation of the results is carried out with weighting coordinated with Central European climate conditions.
In one aspect the evaluation for the new test procedure was somewhat relaxed in comparison to the first round, i.e. in the case of isolation resistance. Although the tests are still performed both after delivery and after the aging tests, their weighting in the overall evaluation is now, however, less significant in the case of PV+Test 2.0. (Mirco Sieg)