IEC 60904-7:2019 pdf download

IEC 60904-7:2019 pdf download.Photovoltaic devices – Part 7: Computation of the spectral mismatch correction for measurements of photovoltaic devices
1 Scope and- object
This part of IEC 60904 describes the procedure for correcting the- bias spectral mismatch error introduced in the testing of a photovoltaic device, caused by the mismatch between the test spectrum and the reference spectrum (e.g. AM1.5 spectrum) and by the mismatch between the spectral- responses responsivities (SR) of the reference- cell device and of the device under test- specimen and therewith reduce the systematic uncertainty.- The procedure applies- onty- t扫photovoltaic devices linear in SR as defined in EG 60904 10. This procedure is valid for single-junction devices but the principle may be extended to cover multi-junction devices. The purpose of this document is to give guidelines for the correction of measurement bias the spectral mismatch error, should there be a spectral mismatch betweenthe test spectrum and the reference spectrum as well as between the reference device SR and the device under test specimen SR. The calculated spectral mismatch correction is only valid for the specific combination of test and reference devices measured with a particular test spectrum. Since a PV device has a wavelength-dependent- fresponse spectral responsivity，its performance is significantly affected by the spectral distribution of the incident radiation, which in natural sunlight varies with several factors such as location, weather, time of year, time of day, orientation of the receiving surface, etc., and with a solar simulator varies with its type and conditions. If the irradiance is measured with a thermopile-type radiometer (that is not spectrally selective) or with a PV reference- solar cell device (IEC 60904-2), the spectral irradiance distribution of the incoming light must be known to make the necessary corrections to obtain the performance of the PV device under the reference- solar spectral irradiance distribution defined in IEC 60904-3. If a reference PV device or a thermopile type detector is used to measure the irradiance, then, following the procedure given in this document， it is possible to calculate the spectral mismatch correction necessary to obtain the short-circuit current of the test PV device under test under the reference- solar spectral irradiance distribution in IEC 60904-3 or any other reference spectrum. If the reference PV device has the same relative spectral- response responsivity as the- test PV device under test then the reference device automatically takes into account deviations of the- feal light measured spectral irradiance distribution from the standard reference spectral irradiance distribution, and no further correction of spectral- bias mismatch errors is necessary. In this case, location and weather conditions are not critical when the reference device method is used for- outdoof performance measurements provided both reference cell and test PV device have the same relative spectral response under natural sunlight. Also, for identical relative SRs, the spectral classification of the simulator is not critical for indoor measurements with solar simulators. . If the performance of a PV device is measured using a known spectral irradiance distribution, its short-circuit current at any other spectral irradiance distribution can be computed using the spectralresponse responsivity of the PV- test device under test.
4 Description of method
For many PV devices, the shape of the I-V characteristic depends on the short-circuit current and the device temperature， but not on the spectrum used to generate the short-circuit current. For these devices， the correction of spectrum mismatch or spectral- response responsivity mismatch is possible using the following procedure. For other devices， a measurement of the I-V characteristic shall be done using a light source with the appropriate spectrum. A correction is not necessary if either the test spectrum is identical to the reference spectrum (see IEC 60904-3) or if the- test specimen’s device under test’s relative spectral- response responsivity is identical to the reference- celt device relative spectral- fesponse responsivity. In this case, the reading as obtained from the reference- cell device specifies which- intensity irradiance at the reference spectrum will generate the same short-circuit current in the- test device under test as the test spectrum. If there is a mismatch between spectra (spectrum mismatch) as well as spectral- responses responsivities (spectral responsivity mismatch) then a mismatch correction should be calculated. As the test spectrum and the spectral responsivities always have an assigned measurement uncertainty， for the calculation of the total uncertainty the uncertainty of spectral mismatch shall be always taken into account.