Sensitivity analysis of albedo input settings for vertical facades in community-scale solar irradiance simulation

Time-resolved simulation of BIPV potential in dense urban areas is complex in nature due to the complex urban morphology affecting the global irradiance and shaded portion throughout the year. Many studies have attempted to establish a systematic procedure to perform rooftop PV potential leveraging GIS or 3D digital twin models of urban districts in the last decade. However, most of the studies lacked detailed input of surface optical properties (e.g. albedo, specularity, roughness) constituting the urban canyons: the surfaces in the urban built environment were reduced into a few categories and assigned with uniform optical values for each.

To unveil ambiguity induced by the high-degree assumption, this study aims to analyze the sensitivity of pre-set input parameters’ assumption on urban surface optical properties on BIPV potential estimation. Yearly solar irradiance on PV cells using a RADIANCE ray-tracing engine, which in turn converted into PV potential based on the PV performance model. Two representative districts in Seoul, South Korea are chosen to represent the residential and commercial districts displaying different cityscapes (rendered by heterogeneous form factors, exteriors, and morphology of building blocks within).

The objective of the study is two-fold. First, examine the sensitivity of the optical property assumptions of the building exteriors in the district-scale model of the built environment to answer the following question: Is it proper to assign a single, homogeneous optical property to surfaces of the same category, where the entire model surfaces are classified into a minimal number?

Two, develop a pipeline to assume a proper set of surface values of the district-scale model aided by GIS information and publicly available image datasets, streamlining the modeling procedure without compromising the accuracy of PV potential estimation.