Wind Resistance of a Solar Panel Mounting Structure with Partially Defective Pile Foundations

During the last decade, damage to photovoltaic power plants caused by natural disasters, mainly by strong winds during typhoons, has been reported repeatedly. Some reports have described frames damaged because the piles were pulled out by wind loads, even though the wind speeds recorded at the corresponding areas did not reach the designed wind speed. Because photovoltaic power plants sometimes extend beyond a few hectares, it is time-consuming and costly to conduct ground explorations of entire areas and to avoid foundation defects completely. Moreover, solar panel mounting structures generally have no structural redundancy, especially in the out-of-plane direction of mounted panels. To explore the failure mechanisms of a solar panel mounting structure with foundation defects and to suggest possible measures, a series of pressure loading tests were conducted at actual scale for a solar panel frame with 20 modules spreading about 4 m × 8 m. Although the mounting frame with no foundation defect sustained pressure of 2500 Pa with minor damage, which was two times greater than the design wind pressure of 1333 Pa, the cover glass of one module was broken at pressure lower than 800 Pa when part of a frame was lifted because of a foundation defect.