Spectral characterization of the solar resource of a sunny inland site for flat plate and concentrating PV systems

Abstract

The spectrum is not frequently used when rating any PV technology. Moreover, in those energy predictions where it is considered, normally they are based on simulated models. The objective of this work is the spectral characterization of the solar resource based on real measurements as their availability in the scientific community is scarce. For this characterization the Average Photon Energy is used, which has been obtained from an experimental campaign carried out in Jaén (Spain) based on three different configurations: Direct Normal spectrum (DNI tracker), Global spectrum on a tracking system (Gl tracker) and Global spectrum on a fixed surface (Gl fixed). The results show that the annual irradiance weighted average value of APE results in 1.80 eV for DNI tracker, 1.85 eV for Gl tracker and 1.86 eV for Gl fixed, showing a red spectral shift for the DNI measurements. A Red-rich spectrum prevails, so this location is especially suitable for single junction materials with a large absorption band such as CIGS and c-Si. Besides, GI tracker spectra are slightly redder than GI fixed ones, consequently, if c-Si modules are used, spectral gains with 2-axis tracking will be higher than those achieved with a fixed arrangement of such modules.