JRC – RSE bilateral intercomparison of solar irradiance measurements

This week, scientists of the European Solar Test Installation (ESTI) and of the Italian research institute Ricerca sul Sistema Energetico (RSE) will perform a bilateral intercomparison on solar irradiance measurements at the European Commission's Joint Research Centre Ispra site (Italy).

ESTI functions as European reference laboratory for calibration of photovoltaic (PV) devices and in order to harmonise measurement instruments, both the total irradiance and the solar spectrum will be measured simultaneously by a set of pyranometers, pyrheliometers, reference cells and spectroradiometers.

ESTI’s primary cavity radiometers are directly traceable to the World Radiometric Reference Group in Davos (Switzerland) and will serve as a reference for the comparison. Increasing demand in accuracy and precision for solar cell calibration is an ever more demanding task. Today, the aim is to arrive at uncertainties in the same order of magnitude of the reference absolute radiometers in Davos.

Irradiance measurements give the greatest contribution to the final uncertainties in the performance estimation of photovoltaic modules, and have a direct impact on the end-user price of the modules on the market, because the more precise our measurements are, the more certainty investors have on their investments.

Therefore, measuring spectrally resolved solar irradiance is crucial in the photovoltaic field, in order to understand correctly the performance of last generation photovoltaic devices, both for terrestrial and space applications: organic, dye-sensitized, perovskites, multi-junction devices, whose performance is strongly dependent on solar spectral distribution.