Yield and quality tests for solar modules
The PHOTON bronze, silver and gold standard
Conventional standards and certificates offer only a small amount of information about the properties of a solar module. The more you find out about a module beyond this basic information, the cheaper solar power is to produce. That is because the more precisely a plant operator can estimate the expected electricity yield of a module type, the lower the investment risk will be. This reduces the cost of capital (not only for larger projects, but ultimately also for private investments).
PHOTON has therefore started testing solar modules back in 2004. From now on, these tests will be supplemented by a new test program.
The widespread IEC certificate, for which practically every solar module today is eligible, has little significance. The requirements specified by IEC 61215 for crystalline solar modules are so low that they do not constitute a serious hurdle for a module manufacturer. Another shortcoming is the lack of practical relevance: The various stress tests used to produce signs of aging are carried out on different models of the module type to be tested - in reality, however, each module is exposed to all stress factors, such as UV radiation, temperature cycles or humidity. In addition, new findings from research are only included in the certification process after an extended period of time. A current example is the degradation of PERC modules.
PHOTON has therefore developed three test cycles that provide information on product quality, service life and yield.
Both the rapid test and the endurance test were developed in cooperation with the PI Photovoltaik-Institut Berlin, and are also carried out there. PI Berlin operates an IEC 17025 certified test laboratory for solar modules.
The tests also allow for the current state of research and are kept as practical as possible. For example, a single module is exposed to all three primary stresses occurring during operation. The fact that several specimens of one type are still required for the test is due to the fact that there are also destructive tests, and that the electrical properties – especially the vulnerability to the known degradation mechanisms – can best be examined on a module that has not been subject to stress.
The grading system of PHOTON’s module tests
PHOTON rapid test (bronze standard)
This test allows a fast, but at the same time meaningful assessment of the module quality. It reveals product defects and gives an outlook on the expected decline in performance due to degradation effects. It is comparatively inexpensive and takes only four to six weeks (depending on the module type). The result is a score that buyers can use as a guide.
PHOTON lifetime test (silver standard)
The lifetime test lasts about ten months and is based on the rapid test. It allows an even better estimation of the expected operating time. The basic idea is that all strains occurring in practice are carried out over and over again on the same module until a decrease in performance is shown. The later this happens, the longer a module will last in real operation.
The result is a logo with a statement about the lifespan and the grade of the quick test. We currently differentiate between »short«, »medium« and »long« in terms of service life. With increasing experience, this will be indicated in years with reference to a particular climate zone.
PHOTON yield measurement (gold standard)
The PHOTON laboratory began measuring the yield of solar modules already in 2004. The test series quickly became the world's largest of its kind. In the meantime, results are available for around 200 different module types for the period up to June 2015. The measurements have been paused in 2016 and 2017, but are to be resumed in 2018. The result is a logo with the performance ratio, i. e. the indication of how well the solar radiation has been converted into electricity, as well as information on a module’s placement in the entire test field, both for the last test year in each case. The yield measurement can be carried out independently of quick test and lifetime test. A result is available after one calendar year.
If the yield test is carried out in addition to the quick test and service life test, this combination allows the best possible assessment of a solar module. The PHOTON »Gold-Standard« logo is available for this purpose.
In addition to the detailed logos with information about the grading, endurance and yield, there is a reduced logo for publication on data sheets or other places where space is very limited. This logo merely conveys the information that a manufacturer is participating in the PHOTON module test. The test results can then be retrieved via the QR code.
We will be happy to answer any questions you may have regarding PHOTON module tests.
Oliver B. Ashrafi