Spectral characterization of spectrally selective liquid absorption filters and exploring their effects on concentrator solar cells

Spectrally selective liquid absorption filter can be utilized to enhance performance of PV/T concentrator (CPV/T) systems by splitting solar spectrum into two wavelength bands. In this paper, the optical transmittance of several liquid filters that might be used for CPV/T systems is characterized and their filtering performance is evaluated. The results show that the liquid filters, except for copper sulfate aqueous salt and Valvoline oil, exhibit high transmittance in the wavelength ranges of both silicon concentrator cell and GaAs cell interest, whereas oil filters perform moderate absorption in the NIR range. The effects of these selected liquid filters on the electrical characteristics of concentrator solar cells are reported. Among all selected liquids, oil filters except for Valvoline, and glycols are proved to be the better choices for generating higher cell efficiencies. Finally, a merit function is introduced to evaluate if the liquid filter would effectively convert sunlight into usable energy in systems. The study concludes inorganic aqueous salts except for copper salts, glycols, and Valvoline oil yield market value increase of more than 20% and 34% for silicon cell and GaAs cell, respectively, when compared to PV alone. Of all selected liquids, Valvoline oil produces the highest merit function value.