Experimental validation of a novel light-splitting technique for retrofitting CSP plants by hybridizing with CPV

Photovoltaic (PV) solar power generation is expanding rapidly relative to Concentrating Solar Power (CSP) due to a faster decline in solar PV panel costs after manufacturing commenced in east Asia in the 1990s. One remaining advantage of CSP is thermal energy storage (TES) which allows for smoothing output and timed dispatch of power at utility scales, whereas PV power, which currently has lower investment and levelized costs, is dependent on battery storage that has not yet matured at a large scale. There are potential advantages in hybridizing the two technologies if the low investment cost and higher areal basis yield of PV can be combined with CSP's robust and scalable storage. Under the Advanced Research Projects Agency-Energy (ARPA-E) FOCUS program, our team developed a novel approach to achieve CSP-PV hybridization through an add-on package that can retrofit existing parabolic trough collector (PTC) plants with secondary spectrum-splitting optics and a concentrating PV (CPV) receiver. The dichroic filter transmits UV and IR solar irradiance to the standard evacuated tube heat collection element (HCE) while wavelengths that are optimally utilized by PV are reflected down to an actively cooled flow through CPV receiver. The fraction of solar energy remaining available for storage can be tuned between 20-100% through configuration of the extension and optical properties of the filter. An experimental section of a standard RP3 mirror parabolic trough and HCE outfitted with the upgrade demonstrates the proof-of-concept for the approach and validates key technical and economic performance targets. The results of these experiments are relevant to operators of CSP plants as a means of enhancing output and return on investment.