The Nuts and Bolts of PV: Maturing Solar PV Racking and Module Mounting Critical Bolted Joint Technologies for LCOE Reductions and Increased Reliability

Industry stakeholders have to date largely overlooked both the critical role and uniqueness of bolted joints found in solar PV systems. Bolted joints seen in solar PV racking and module mounting lack the technological maturity exhibited in comparable industries to deliver low cost and high reliability solutions critically needed for further advancement of the industry. As a result they have regularly failed, which can have results ranging from unexpected system maintenance to entire PV system failures--in severe weather events and in normal operating conditions. This paper will overview and categorize the current state of PV bolted j oint technologies, provide an engineering analysis of failure modes, identify codes and standards gaps leading to inconsistent bolted joint application in the field, summarize and publicize data gathered from a surveying and interviewing effort on field failures, share results of structural lab physical testing of common PV system bolted joint typets and the CFD flow models they inform, and develop a lifetime cost accounting model and tool for determining the cost impacts of various bolted joint and hardening options. The paper format is that of a technical guidance document, backed by empirical evidence aimed at near and long-term influence; product engineers for near-term and codes and standards committees for long-term advancement.