Design and Performance of a 1.5 axis Sun tracking Concentrated Photovoltaic System

Abstract

This paper reports the design and testing of a concentrated solar photovoltaic thermal (CSPVT) system. The system consists of the PV panel, its cooling system, the parabolic concentrator, and the sun tracking mechanism. Photo Voltaic Thermal (PVT) systems are already a promising technique for improving energy yields and efficiencies of PV panels. The current work adds a concentration effect to make further improvements, especially on yields. Unlike the case of other research which uses plane mirrors along the sides of PV panels, this work employs a single parabolic reflector of concentration ratio 1.3, integrated with the panel mounting. A cooling system is also integrated with the mounting, so that the specially designed sun tracking mechanism turns the entire assembly, keeping both panel and reflector facing the sun without affecting the coolant flow in the adjoining pipes. This is one of the novelties of this work. We use vertical axis tracking but with seasonal adjustment of tilt. Hence the 1.5 axis in the title of this paper. Southern hemisphere spring tests in Cape Town showed a 60.2% electric power gain when compared with yields from an identical fixed panel. We also develop and test a MATLAB program using actual weather data for the experimentation period, and do a TRNSYS simulation using the software’s embedded TMY (typical meteorological year) weather data for the period. We find MATLAB results to be closer to experimental ones, while TRNSYS ones are not far out on totals. We conclude that CSPVT has much potential to increase both yields and efficiencies. In addition, we suggest that TRNSYS simulation would probably be most useful in cases where actual weather data is not available.