Growing Panes: Investigating the PV Technology Trends Behind Frequent Early Failures in Modern Glass-Glass Modules

Photovoltaic (PV) module materials and technologies continue to evolve as module manufacturers and buyers try to minimize costs, maximize performance, and speed deployment. Both silicon and thin film modules are converging towards similar ~3 m^2 glass-glass designs with thinner glass sheets to increase power output while reducing module weight, and both types are increasingly mounted on single-axis trackers. At the same time, an increasing number of PV sites have been reporting spontaneous glass breakage in early-life systems deployed with these "big, floppy modules." In this article, we identify the concurrent module changes that may be contributing to increased early failure, explain the trends, and discuss their reliability implications. We suggest that larger, thinner glass sheets along with variations in heat treatment and quality may be contributing to glass vulnerability. We note that trends toward weaker or back-mounted frames may also be contributing to module failures, especially for "extra-extra-large" modules mounted on trackers. Combinations of these trends may have pushed modules to a threshold at which increasing early failures are causing the front edge of the "bathtub curve" to reemerge. Current qualification testing appears to be ineffective for catching these early failures in new module designs, and module buyers do not have enough reliability information - or cannot prioritize such information - during module procurement. Additional research is needed to identify the field conditions leading to glass breakage and if there is one or multiple limiting flaws in new module designs causing glass breakage. Early failures may be mitigated by returning to more robust designs or ensuring better module testing and quality assurance.