Passive Cooling of Photovoltaic Panels Using Fluid-Based Spectral-Beam Splitting Filters
Abstract
One of the biggest problems in photovoltaic panels is heat, reducing its performance drastically due to high temperatures. Spectral beam splitting SBS is a passive cooling method that involves separating sun´s electromagnetic wavelength to lead the most appropriate range to photovoltaic panel while absorbing the rest as heat, thus reducing temperature of the panel and diminishing losses. However, when it comes to applying the method in the real world, it is a complicated task due to the synergistic considerations of optical, thermal and electrical behavior of the whole collector. This work has assessed water, propylene glycol 99%, and motor oil as spectral filters in a test bench to compare simultaneously 2 panels (reference and with SBS filter) and record the temperature decrease. The use of the SBS filter reduced the surface temperature of the PV panel surface with respect to the reference PV panel in 7°C, 5°C, and 9°C for water, propylene glycol 99%, and motor oil, respectively. Photo thermal efficiency was calculated, obtaining 27% with water, 16.1% with PG 99%, and 17.4% with motor oil. Electrical efficiency was computed based on actual power that panels produced working in MPP in real environmental conditions (either a solar charge controller or microinverter) producing more representative results of real output. The electrical efficiency obtained following this method was 11.7 % for water, 11.6 % for propylene glycol and 8.7% for water. The methodology used in this work allows for a better understanding of how to assess efficiency when applying this cooling method.
Keywords
Photovoltaic, spectral filter, cooling method, water, propylene glycol, motor oil.