ASTM E973-16

5.2.1 The spectral mismatch parameter is formulated as the fractional error in the short-circuit current due to spectral and temperature differences.

5.2.2 Error due to spectral mismatch is corrected by multiplying a reference cell’s measured short-circuit current by 5.3 Because all spectral quantities appear in both the numerator and the denominator in the calculation of the spectral mismatch parameter (see 8.1), multiplicative calibration errors cancel, and therefore only relative quantities are needed (although absolute spectral quantities may be used if available).

5.4 Temperature-dependent spectral mismatch is a more accurate method to correct photovoltaic current measurements compared with fixed-value temperature coefficients.1.1 This test method provides a procedure for the determination of a spectral mismatch parameter used in performance testing of photovoltaic devices.

1.2 The spectral mismatch parameter is a measure of the error introduced in the testing of a photovoltaic device that is caused by the photovoltaic device under test and the photovoltaic reference cell having non-identical quantum efficiencies, as well as mismatch between the test light source and the reference spectral irradiance distribution to which the photovoltaic reference cell was calibrated.

1.3 The spectral mismatch parameter can be used to correct photovoltaic performance data for spectral mismatch error.

1.4 Temperature-dependent quantum efficiencies are used to quantify the effects of temperature differences between test conditions and reporting conditions.

1.5 This test method is intended for use with linear photovoltaic devices in which short-circuit is directly proportional to incident irradiance.

1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.