Investigation and performance characteristics of a hybrid solar photovoltaic-thermoelectric power generation renewable energy system

Abstract

Increasing fossil fuel prices, electricity demand, and global concern for greenhouse gas emissions have increased interest and research of novel renewable energy technologies. Renewable solar-photovoltaic (PV) systems are known for their ability to directly convert solar energy into electrical energy, however, their performance degrades when operating at elevated temperatures. Thus, decreasing the temperature of PV modules using efficient cooling methods tend to improve their overall efficiency and increase power production. Thermoelectric power generation (TEG) technology has the innovative capability to convert a portion of the waste-heat energy dissipated from PV systems directly into electricity, and simultaneously reduce the PV systems operating temperature. Hybrid photovoltaic-thermoelectric power generation (HPV-TEG) systems integrate TEG modules with a PV module to form a more efficient power generation system. There has been a lack of research that has explored this hybrid concept and characterized in detail the performance of HPV-TEG systems. Therefore, the main objective of this research work is to investigate the viability and performance characteristics of a HPV-TEG system through detailed numerical and experimental studies. Numerical simulations showed that the HPV-TEG system was able to generate more electricity than a conventional PV system while operating at high solar radiation intensities and ambient temperatures. Two HPV-TEG test setups (indoor & outdoor) were designed, constructed and fully instrumented in order to achieve the main objective of this research. Detailed indoor and outdoor experimental tests and case studies were consistently performed. Optimization of the HPV-TEG system showed that the addition of an aluminum layer increased the PV and TEG power output by approximately 6.9% and 350%, respectively. The infrared thermal imaging results showed that the HPV-TEG systems’ cooling system efficiently reduced the systems’ operating temperature. In the outdoor tests, the HPV-TEG systems’ minimum and maximum overall daily efficiency were 3.68% and 9.45%, respectively. For all the tests, it was found that the daily electrical energy output from the HPV-TEG system was always higher than the conventional PV system (in one case about 6.4% higher). Finally, a predictive sizing correlation was developed to estimate the power density generated by an HPV-TEG system as a function of solar radiation, ambient air temperature, and TEG’s coolant inlet temperature. A conceptual scheme was also proposed in this study for large-scale application using the promising green HPV-TEG technology.