The Role of Solar Spectral Beam Splitters in Enhancing the Solar-Energy Conversion of Existing PV and PVT Technologies

The use of photovoltaics (PVs) and/or photo-thermal (PTs) as primary solar-energy solutions is limited by the low solar conversion of PVs due to the spectral mismatch between the incident radiation and/or the PV material. The PTs are curtailed by the limited absorbance and the low thermal conductivity of the working fluid. A possible solution is the use of luminophores able to perform luminescent down-shifting (LDS) conversion and to incorporate them in liquid or solid layers, which act as spectral beam splitters (SBSs). Dispersed in solid polymer layers, luminophores lead to luminescent solar concentrators (LSC). When dispersed in liquid and placed in front of PVs, luminophores act as working fluids and as SBS, leading to hybrid photovoltaic–photo-thermal (PVT) systems. Here, the SBS filters for PV and PVT systems are reviewed. The contribution of luminophores to electrical and thermal energy production is discussed from theoretical, experimental, and economical perspectives. Recent SBS architectural concepts which combine different optical elements are also considered. These architectures can harness the advantageous properties of LSCs, spectral modulators, and hybridisation in a single structure. By combining these different light-management strategies inside of a single structure, an improvement in the electrical and/or thermal energy production can be achieved.