IEC 62787-2021 pdf free download – Concentrator photovoltaic (CPV) solar cells and cell on carrier (CoC) assemblies – qualification.
The number of devices to be tested in each qualification test shall not be less than the sample
sizes specified in Clause 8. ln order to provide statistical meaning to the number of devices,IEC 61193-2 has been used since it assigns a defect probability as a function of number ofsamples.
The samples for each test of Table 1 and Table 2 shall be chosen randomly from thequalification lot. The qualification lot shall be a production lot of at least 1 000 bare cells/CoCs.The production lot shall be formed from at least two epitaxial runs and three metalARCdepositions carried out in different weeks.
6Marking
Due to the very small bare solar cell dimensions any marking on cell is usually not possible.Therefore, an ID mapping needs to be applied.Regarding CoC under test, they shall be clearly
marked or identified for later tracking of data records. The required information for both barecells and CoCs are:
– name, monogram, or symbol of manufacturer;
– type or model number;
serial number;
polarity of terminals or leads;
the date,place of manufacture, and cell materials should be marked, or be traceable fromthe serial number.
7 Characterization methods for measuring the performance of bare cells and Cocs subjected to qualification tests
7.1General
The optoelectronic performance characterization based onilluminationI-v curves tries toidentify optoelectronicperformance degradation of test samples caused by the requiredqualification tests. Therefore，illumination l-v curve has to be performed before and afterqualification tests. The goal of the illumination l-V curve is on the relative power degradation,
not on the absolute power output. Scanning Acoustic Microscopy(SAM) is also required butonly for CoCs.
ln addition, electroluminescence mapping and dark l-V curve can provide diagnostic information
about defects and changes within the device. Before and after qualificationtesting, dark l-vcurve can be carried out for the voltage and current ranges of interest. Electroluminescenceimages are not explicitly suggested through this document, but they could be of great help when
captured for each device at different current injection levels before and after some qualificationtests.
7.2 Light l-V measurement
This is a compulsory characterization method. All test samples shall be measured at 25 “C,under AM1.5D spectrum as specified in IEC 62670-1, and at an overal lightintensityrepresentative of the intended application. For the purposes of this characterization method,1 sun equivalent of the AM1.5D spectrum will have a total power density (irradiance) of 0,1 WIcm 2.
so that a light intensity of 100 Wicm 2 = 1 000 suns. The parameters and measurement methods
for the light l-v measurement are defined in lEC 60904-1-1:2017.
llumination l-V curve has to be performed before and after qualification tests. The focus of the
illumination l-v curve is on the relativepower degradation,not on the absolute power output.The relative power degradation,Pa, is defined as follows:
At a minimum, J sc (short circuit current density), V oc (open circuit voltage), FF (fill factor), P max (maximum power) and efficiency should be used in this document and have to be included in the qualification report for pre/post stress test evaluation.
7.3 Dark I-V measurement General
7.3.1 This is a compulsory characterization method for the Electrostatic Discharge (ESD) Damage Threshold test while is optional for the rest. The high operating current density of CPV devices, can sometimes mask detection of low level defects or the onset of degradation. Dark I-V measurements performed before and after a qualification test can provide a more sensitive measure of damage or degradation.IEC 62787 pdf download