Performance Analysis of an Inverted Trapezoidal Flume Shaped Photovoltaic Thermal System

The photons in the solar spectrum with energy equal to or higher than the band gap energy of the solar cell material are potentially useful for photo electricity. However, as most of the commercial solar cells have negative thermal coefficients; during operation, the unused photons cause thermal losses in these solar cells, and affect their electrical conversion efficiency. To overcome these losses, combined Photovoltaic Thermal systems (PVT) are developed. In these systems, heat is extracted from the PV module to improve its performance. This extracted heat is used separately for thermal applications. Thus, the system gives both electrical and thermal output simultaneously. Several such PVT systems have been reported in the past. In the current study, an inverted trapezoidal flume shaped PVT system is designed. The system is equipped with the flat mirror reflectors from all sides. Water is used as working medium to extract the heat from the PV module. The performance of the system is analyzed experimentally at Nagpur [21° N, 79° E] for different operating conditions. The experimental results had shown significant improvement in the electrical efficiency of PV module. Maximum average electrical efficiency and maximum overall efficiency of the system were found to be 10.42 and 62% respectively. Constructional details of the system and the performance analysis are discussed in this article.