Solar Cell Efficiency Measurements

The calibration and efficiency measurement procedures followed by the PV Devices and Measurements Branch at the Solar Energy Research Institute (SERI) are presented. The use of spectral irradiance measurements to calibrate reference cells used in these measurements has reduced the uncertainty in the calibration number to less than 1%. The use of the spectral mismatch index can reduce the errors in short-circuit current measurements to about 2% for a wide variety of test cell/reference cell combinations and reduce the need for a close match between the test cell and reference cell spectral responses or the source spectrum and standard spectrum. The effect of various spectra in use by the PV community on the short-circuit current is presented for a variety of cell spectral responses.