This part of IEC 60904 describes the procedure for correcting the bias error introduced in the
testing of a photovoltaic device, caused by the mismatch between the test spectrum and the
reference spectrum and by the mismatch between the spectral responses (SR) of the
reference cell and of the test specimen. The procedure applies only to photovoltaic devices
linear in SR as defined in IEC 60904-10. This procedure is valid for single junction devices
but the principle may be extended to cover multijunction devices.
The purpose of this standard is to give guidelines for the correction of measurement bias,
should there be a mismatch between both the test spectrum and the reference spectrum and
between the reference device SR and the test specimen SR.
Since a PV device has a wavelength-dependent response, 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 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 reference solar cell, 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 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 standard, it is possible to calculate the spectral mismatch
correction necessary to obtain the short-circuit current of the test PV device under the
reference solar spectral irradiance distribution included in Table 1 of IEC 60904-3 or any
other reference spectrum. If the reference PV device has the same relative spectral response
as the test PV device then the reference device automatically takes into account deviations of
the real light spectral distribution from the standard spectral distribution, and no further
correction of spectral bias errors is necessary. In this case, location and weather conditions
are not critical when the reference device method is used for outdoor performance
measurements provided both reference cell and test PV device have the same relative
spectral response. Also, for identical relative SR’s, the spectral classification of the simulator
is not critical for indoor measurements.
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
spectral response of the PV test device.
BS EN 60904-7:2009 Referenced Document
IEC 60891 Photovoltaic devices - Procedures for temperature and irradiance corrections to measured I-V characteristics*, 2021-10-27 Update
IEC 60904-1 Photovoltaic devices - Part 1: Measurement of photovoltaic current-voltage characteristics*, 2020-09-25 Update
IEC 60904-2 Photovoltaic devices - Part 2: Requirements for photovoltaic reference devices*, 2023-06-19 Update
IEC 60904-3 Photovoltaic devices - Part 3: Measurement principles for terrestrial photovoltaic (PV) solar devices with reference spectral irradiance data*, 2019-02-15 Update
IEC 60904-8 Photovoltaic devices - Part 8: Measurement of spectral responsivity of a photovoltaic (PV) device*, 2014-05-01 Update
IEC 60904-9 Photovoltaic devices - Part 9: Solar simulator performance requirements*, 2020-09-18 Update
IEC 61215 Crystalline silicon terrestrial photovoltaic (PV) modules - Design qualification and type approval
IEC 61646 Thin-film terrestrial photovoltaic (PV) modules - Design qualification and type approval
BS EN 60904-7:2009 history
2009BS EN 60904-7:2009 Photovoltaic devices — Part 7: Computation of the spectral mismatch correction for measurements of photovoltaic devices