IEC 62787 pdf free download

IEC 62787 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. In 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 of samples.
The samples for each test of Table 1 and Table 2 shall be chosen randomly from the qualification lot. The qualification lot shall be a production lot of at least 1 000 bare cells/CoGs. The production lot shall be formed from at least two epitaxial runs and three metal/ARC depositions carried out in different weeks.
6 Marking
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 bare cells 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 from the serial number.
7 Characterization methods for measuring the performance of bare cells and CoCs subjected to qualification tests
7.1 General
The optoelectronic performance characterization based on illumination I-V curves tries to identify optoelectronic performance degradation of test samples caused by the required qualification tests. Therefore, illumination I-V curve has to be performed before and after qualification tests. The goal of the illumination I-V curve is on the relative power degradation, not on the absolute power output. Scanning Acoustic Microscopy (SAM) is also required but only for CoCs.
In addition, electroluminescence mapping and dark I-V curve can provide diagnostic information about defects and changes within the device. Before and after qualification testing, dark I-V curve can be carried out for the voltage and current ranges of interest. Electroluminescence images 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 qualification tests.
7.2 Light I-V measurement
This is a compulsory characterization method. All test samples shall be measured at 25 °C, under AMI.5D spectrum as specified in IEC 62670-1, and at an overall light intensity representative 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 W/cm2, so that a light intensity of 100 W/cm2 = 1 000 suns. The parameters and measurement methods for the light I-V measurement are defined in IEC 60904-1-1:2017.
7.7 Thermal resistance measurement
This is a characterization method for CoC test at high temperature with current injection for identifying thermal defects that shall be carried out before and after test. The procedure is:
• Place the CoC in good thermal contact onto a carrier with a programmable temperature controller, under natural convection. Place a very thin thermocouple between the CoC and the carrier just beneath the solar cell location. The programmable temperature can be achieved by Peltier cooling module, liquid chiller, etc. Set the temperature at (40 ± 0,4) °C.
• Forward bias the CoC at 0,5 ‘Sc (achieved at maximum concentration). After a transient period the steady state solar cell temperature is achieved where the voltage of the CoC is measure so, the dissipated power of CoC (c0c) can be determined.
• Measure the backplate CoC temperature (Tbp) by the thermocouple.
• Take a picture of the solar cell with an Infrared Thermographic Camera (ITC), at the normal direction to the CoC surface. This ITC shall have a pixel resolution well below the solar cell size. Take the maximum solar cell temperature (Ta) shown by infrared picture.IEC 62787 pdf download.