Quality Control / Warranty Testing for Power Plant Projects
Projects in this category typically test a subset of modules (0.1-1%) for performance relative to nameplate to ensure that the module manufacturer delivers consistently good modules. Additional tests can be added to performance tests, such as EL imaging to check for shipping/handling damage, IR imaging to determine if modules are prone to hot spots, as well as reliability tests to verify modules can withstand long term environmental stresses. Often these tests are combined with outdoor yield studies in which the modules are installed similarly to the planned field installation (e.g. on a single axis tracker or fixed rack) with a similar inverter as used in the field, to verify the yield predictions done through theoretical modeling by the project planners.
Another goal of this kind of testing is to verify warranty claims. If power plants provide lower than expected output, it is possible to test individual modules to see if they produce less power than specified. Since there are always measurement uncertainties, however, the difference between expected and actual power has to be typically more than ~5% to prove a significant underperformance of modules compared to nameplate ratings.
It is advantageous to characterize modules before installation and on a yearly basis on the same flash test equipment. In this case measurement uncertainties from the test equipment can be excluded and much lower performance deviations can be substantiated.