Intercomparison campaign of spectroradiometers for a correct estimation of solar spectral irradiance: results and potential impact on photovoltaic devices calibration

This paper describes the results of an intercomparison of spectroradiometers for global and direct normal incidence irradiance in the visible and near infrared spectral regions together with an assessment of the impact these results may have on the estimation of the short-circuit current (Isc) calibration of photovoltaic devices and on the spectral mismatch calculation. The intercomparison was conducted in the framework of the European project Apollon with the additional participation of external partners from the Italian project for the long-term monitoring of solar radiation for photovoltaics. Six institutions and six spectroradiometer systems, representing different technologies and manufacturers, were involved. Prior to the imtercomparison, all participating partners calibrated their own instrument(s) according to their usual procedures in order to verify the entire measuring and traceability chain. The difference in measured spectra shape and amplitude showed to have an impact on Isc calculation of less than 3% and less than 6% for single-junction and multi-junction devices, respectively. When only the shape of the spectra is considered, the specta mismatch ranges from 1.7% to 4.7% depending on the spectral response of the device.