Evaluation of model fidelity for solar analysis in the context of distributed PV integration at urban scale

This paper examines the level of model fidelity required to support design phases in the urban solar planning process. The two modelling features crucial to the fidelity of the photovoltaic (PV) yield prediction on urban surfaces are (1) a level of fidelity for modelling urban shading and solar reflection and (2) a level of fidelity for modelling PV system operation. The paper compares three different models for predicting urban shading and reflection and two different PV models for predicting PV system operation. The relevance of the model fidelities is investigated through a case study of an urban area in Wuhan, China under three decision-making contexts: setting a solar target, place-making, and economic assessment for urban-scale distributed PV integration. Predictions for the decision-makings are generated using the selected models through computational simulation under the same annual weather profile. The results show that the relatively less accurate canyon-based method tends to overpredict with 57 buildings identified as suitable for PV installation for walls in the studied urban area; the more accurate vector-based model predicts only 14 suitable buildings. The results predicted with additional consideration of dynamic PV system operation exhibit differences from those predicted by the static PV system model, with a difference of roughly 13 buildings on average within each payback-time category. The differences are noticeable but can be regarded as incremental for urban-scale economic assessment compared with the significant difference due to the fidelity level of modelling urban shading and reflection.