Inaccurate model inputs

Inaccurate model inputs are errors in the data that go into an energy-yield model, for example module data entered incorrectly or a wrong count of modules per string or of parallel strings. A wrong or unrepresentative PAN module file skews the simulated module performance. The yield expectation then differs from what the field delivers, even though nothing is physically wrong with the plant. This failure mode is called flawed PAN file yield losses. Terrain undulation yield losses happen when backtracking and energy models assume simplified terrain geometry. Rows can follow their commands correctly and still have uneven apparent spacing, nonuniform tracker angles or too much shading, so the command itself may be the problem. The typical sign is a lasting gap between expected and measured performance that remains after weather, availability, clipping, curtailment, soiling, degradation and instrumentation have been checked. Terrain-related losses repeat with sun position. They are strongest when the sun is low and tend to cluster at motor block boundaries, grade breaks, swales and rolling sections. Keep a model-baseline problem separate from real operational losses, so it is not mistaken for a field defect that can be repaired. To reduce exposure, use validated module files, record which PAN source and version was used, run sensitivity analysis, and update forecasts when independent tests show different parameters. On rolling sites, tune backtracking by terrain zone, check the motor block sizing assumptions, and update energy models with measured row-level behavior.