Cálculo analítico e interpretación de la incertidumbre de la medida de irradiancia solar global, difusa y reflejada

Resum

In order to model and simulate solar energy plants (photovoltaic, thermal or hybrid) it results mandatory to characterize the site’s solar potential. Moreover, for the complete integration of those systems in buildings and other urban structures, horizontal irradiance measurements are not enough and the value of all its components on any tilted and oriented surface is needed. Solar irradiance measurements are usually carried out by two radiometric instruments: the pyranometer for the measurement of global, diffuse or albedo’s irradiance, and the pyrheliometer for the direct beam irradiance. Although calibration methods in laboratory have been developed and reference instruments uncertainties have been studied, there is no agreement about the uncertainty calculation process for field instruments. This work first analyses the mean error sources existing in the measurement of each irradiance component. Foremost, a systematic procedure for the expanded uncertainty calculation is proposed. It takes into account the measured irradiance component type, the tilting and pointing angles of the sensor and the climatic conditions. This procedure has been applied and interpreted for several radiometric instruments from the radiometric stations managed by the SWIFT Research Group.