IEC_904-1.pdf

904-11EC1987-5-PHOTOVOLTAIC DEVICESPart 1:Measurement of photovoltaiccurrent-voltage characteristics1.ScopeThis standard describes measurement procedures for current-voltage characteristics of crystal-line silicon photovoltaic devices in natural or simulated sunlight.These procedures are applicableto a single solar cell,a sub-assembly of solar cells,or a flat module.Nores I.-The termspecimenis used to denote any of these devices.2.-These procedures are limited to linear devices.2.General measurement requirements2.1 The irradiance measurements shall be made using a calibrated reference device as specified in therelevant future IEC publication.2.2 The reference device shall have essentially the same relative spectral response as the specimenand shall be selected and calibrated in accordance with the relevant future IEC publication.2.3 The temperature of the reference device and specimen shall be measured to an accuracy of+1C.If the temperature of the reference device differs by more than 2C from the temperature at whichit was calibrated,the calibration value shall be adjusted to the measured temperature.2.4 The active surface of the specimen shall be coplanar within5 with the active surface of thereference device.No collimators shall be used.2.5 Test connections are shown in Figure 1,page 10.2.6 Voltages and currents shall be measured to an accuracy of+0.5%using independent leads fromthe terminals of the specimen.2.7 Short-circuit currents shall be measured at zero voltage,using a variable bias(preferably electronic)to offset the voltage drop across the external series resistance.Alternatively,they may be deter-mined by measuring the voltage drop across a precision 4-terminal fixed resistor provided that ameasurement is made at a voltage not higher than 3%ofthe device open-circuit voltage,within therange where there is a linear relationship between current and voltage,and the curve is extra-polated to zero voltage.2.8 Voltmeters shall have an internal resistance of.at least 20 k/V.2.9 The calibration ofall instruments shall be certified to be within the required accuracy at the time ofmeasurement.904-1IEC1987-9-4.5 If the temperature of the specimen is not the desired temperature,correct the measured current-voltage characteristic to this desired temperature using the procedure in accordance with therelevant future IEC publication.5.Measurement in pulsed simulated sunlightPulsed sunlight simulation for photovoltaic performance measurements shall meet therequirements of the relevant future IE C publication.The test procedure is as follows:5.1 Mount the specimen as near as possible to the reference device with their active surfaces in the testplane.The normal of the specimen and the reference device shall be parallel within+5 to thecentre-line of the beam.5.2 Set the irradiance at the test plane so that the reference device produces its calibrated short-circuitcurrent at the desired level.Note.-In some pulse simulators the pulse is triggered by a separate photovoltaic cell when the irradiance reaches a levelwhich has been previously set with a reference device.5.3 Record the current-voltage characteristic and temperature of the specimen(or ambient tempera-ture,ifit is the same).The time interval between the data points shall be sufficiently long to ensurethat the response time of the test specimen and the rate of data collection will not introduceerrors.5.4 Correct the measured current-voltage characteristic to both the desired temperature and irra-diance in accordance with the relevant future IEC publication.6.Test reportWhen a test report is required it shall contain the following data:-a description and identification of the specimen(solar cell,sub-assembly of solar cells ormodule);-test environment(natural or simulated sunlight and,in the latter case,brief description andclass of simulator);irradiance level;-temperatures of the specimen and reference device;-description and identification of primary and/or secondary reference device(cell or mo-dule);-calibration data(where and when calibrated,calibration value);deviations from standard test procedures;test results.