Structural analysis and application of wind loads to solar arrays

Evaluation of a solar array subjected to wind requires knowledge of the aerodynamics of the array as well as the structural response of the array to wind pressures that vary with time and location. Boundary layer wind tunnel testing using pressure-tap models is effective for measuring these pressures. However at the small scale necessary for such testing, particularly when modeling rooftop arrays, it is difficult to create aeroelastic models that can accurately capture the structural response. Nonlinear wind response-history analysis can account for dynamic effects in lieu of aeroelastic testing, with some advantages and limitations. Response-history analysis is a means for investigating the effects of structural dynamics on the behavior of solar arrays and the appropriateness of equivalent static analysis procedures. Key aspects in the implementation of response-history analysis include the effects of damping, nonlinear modeling assumptions, and initial conditions of the analysis. Findings from an investigation using response-history analysis indicate that a solar array support system that is flexible under uplift can resist code design-level winds provided there is adequate structural interconnection and sufficient ballast weight or attachments, particularly at the edges and corners of the array.