Experimental and Finite Element Analysis of Wind Induced Displacement of a Dual Axis Photovoltaic Solar Trackers

Abstract

Photovoltaic (PV) solar panels and trackers represent one of the most common renewable energy technology which converts sunlight radiation into electrical energy. The solar trackers specifically are more complex structures because they involve mechanical devices, a supporting slender structure, and photovoltaic modules mounted and positioned on top of the supporting structure. Solar trackers are mounted on mobile supports or racks, in order to enable the rotation and tilt of the PV which thus maintains their optimum exposure to the incident sunlight. Solar trackers support structures should be designed for wind resistance during the operation and at stow position for its life span and this became a concern considering the new tendency of installing the solar trackers on the rooftop of low-rise or medium-rise buildings. The current research focused on performing site measurements of the wind-induced displacement for a dual-axis solar tracking system installed on the roof of the Mann Parking building of the University of Ottawa, for different azimuth, elevations. The supporting structure of the solar tracker was instrumented with 16 strain gauges and the strains developed in the metal truss members were measured during the months February 2015 and March 2015. The tracker was rotated and tilted at different angles through the duration of the experiment and the strains observed on each structural element were recorded. In order to estimate deflections of the supporting structure for wind speeds higher than the ones measured, a finite element (FE) model of the solar tracker was created and static analysis was performed for different inclinations using the SAP 2000 structural software. The experimental results were in agreement with the FE simulation results as the stresses obtained ranged between 1.02 × 107 Pa and 7.88 × 107 Pa. Lower attack angles between 45° and 60° were found to have significant effect on the elements of the solar tracker irrespective of the wind load magnitude. Operational attack angles between 65° and 75° were found to be safer positions as obtained displacements and stress analysis result showed that the supporting structure of the solar tracker was stable for wind speeds between 0 m/s and 33m/s in Ottawa region