Performance Evaluation of hybrid Photovoltaic - Thermoelectric (PV-TE) Water collector system

Abstract

The photovoltaic modules are one of the most common sustainable electric generators using the radiation of sun. Inherent is the thermal losses in the photovoltaic module due to increase in solar cell temperature which affects the electrical efficiency by 0.03V/o C. Various researchers from the past century have been trying to improve the efficiency of Photovoltaic module using different techniques. Development of new and novel materials and structures of the PV module always remained in focus for improvement of the electrical efficiency. Some of the other techniques are using concentrating mechanism to increase amount of radiation absorbed in multiple of SUN radiation. Which enhances the electrical output of photovoltaic module with higher efficiency. Adding variety of tracking system, to make the solar radiation always perpendicular to the surface of photovoltaic module, also improves the electrical efficiency and total energy output of the system from sunrise until sunset. Some of the early researchers also emphasized on the reduction of various losses associated with PV. One of the losses is the thermal in nature which can be addressed by adding different types of thermal collectors to absorb thermal losses and reduce cell temperature thereby increasing overall energy output of the system. Such systems are called hybrid photovoltaic thermal system (PV-T). In this thesis, a thermal model based on energy balance equations has been developed for photovoltaic thermoelectric flat plate collector (PV-TE-FPC). The PV-TE-FPC model consists of a semitransparent PV module integrated with TE modules to increase the electrical efficiency and a tube-in-sheet arrangement placed below the TE modules for the flow of water and removal of thermal energy from the bottom surface of TE modules. The semitransparent PV module considered in the present study includes polyethylene terephthalate (PET) as the top and bottom cover material of PV module, which offers the advantages of flexibility, transparent, thermal conductive. The developed thermal model has been experimentally validated by performing statistical analysis for fluid outlet temperature for the measured climatic parameters of Buraidah, Saudi Arabia in the months of February, March and April, 2019. The results illustrate a reasonable agreement between the theoretically calculated and experimental values. The electrical energy output of the model varies between 3.96 – 14.38 W and thermal energy output between 41.14 – 148.72 W at 15th of April 2019. The developed thermal model is in fair agreement with the experimental observations with correlation coefficient r = 0.65 – 0.99. The electrical output increased approximately 22% because of adding thermoelectric modules.