Comparative Analysis of Polycarbonate and Glass Cover Configurations for Enhanced Thermal Efficiency in Flat Plate Solar Collectors for Water Heating

This study evaluates the thermal efficiency of flat plate solar collectors using Polycarbonate and Glass covers for solar water heating in India. Results indicated that the glass-covered solar collector achieved an average thermal efficiency of 50.5%, surpassing the Polycarbonate-covered collector s 46.1%. The glass cover resulted in a maximum water temperature increase of 9.1°C, compared to 8.7°C for Polycarbonate. Daily solar irradiance averaged 884.2 W/m² for the glass cover and 874.6 W/m² for the Polycarbonate cover. The glass-covered system generated a daily hot water yield averaging 150 liters at temperatures above 37°C, whereas the Polycarbonate system produced 140 liters under similar conditions. Over 10 tests, the glass-covered collector showed an average temperature gain (ΔT) of 9.1°C, compared to 8.7°C for Polycarbonate. The glass cover’s optical transmittance was 90%, compared to 85% for Polycarbonate, contributing to higher thermal performance. Despite Polycarbonate’s lower cost, its performance was hindered by higher thermal emittance and lower optical transmittance. The glass cover s stability and durability were further demonstrated, showing no signs of degradation after 10 months, unlike the Polycarbonate cover, which exhibited yellowing and scratching. These findings suggest that glass covers provide better long-term efficiency and performance for solar water heating systems.