Hybrid Photovoltaic/Thermal Collector Based on a Luminescent Concentrator

Abstract

The efficiency of a single-junction PV cell — for example, a c-Si solar cell — has a theoretical limit of around 27%–30% [1]. This means that, in the best-case scenario, the device harvests around one-fourth of the solar energy. This relatively low efficiency is due to the impossibility of converting the broad solar spectrum with one semiconductor material. The single-junction cell represents a relatively narrow band, two-terminal device. The spectrally distributed solar radiation requires, in principle, a many-terminal or multijunction device in order to reach a high conversion efficiency. When the single junction is replaced by a multijunction cell in practice, efficiency rises substantially (to about 40% in the last few years, for the triple-junction III-V-based PV cells [2]). But even then it remains relatively low.