Simplified vector-based model tailored for urban-scale prediction of solar irradiance

Wei Liao, Yeonsook Heo, Shen Xu

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)


This paper presents a simplified vector-based model on the basis of consideration of the urban context to effectively predict the solar potential of urban areas. The proposed model is based on vector-based methods without the use of ray trace and ray interception techniques, yet consists of new methods that suitably account for the nonuniform solar radiation of the sky, obstruction by urban surfaces, and reflection by urban surfaces in urban areas. The proposed model establishes three new methods to simplify the calculation in the context of urban applications: (1) a two-segment discretization model, (2) an edge angle detection obstruction model, and (3) a unified view-angle-based reflection model. The performance of the method was compared against the advanced daylight simulation program RADIANCE and measurements obtained from controlled experiments. The first comparison demonstrated the new method's provided flexible setting options for different resolution and prediction accuracy requirements and generated reasonably accurate predictions. The second comparison showed that the proposed model elicited average absolute differences of 6% and 5% compared to the actual measurements from the horizontal and vertical surfaces, respectively. In comparison with ray interception approach, the results showed that the proposed method required a much lower number of calculation iterations for detecting sky and building obstructions.

Original languageEnglish
Pages (from-to)566-586
Number of pages21
JournalSolar Energy
Publication statusPublished - 2019 May 1

Bibliographical note

Funding Information:
This work is supported by the National Natural Science Foundation of China (NSFC) under the Contract No. 51678261 and the CSC Cambridge International Scholarship.

Publisher Copyright:
© 2019 International Solar Energy Society


  • Model validation
  • Simplified irradiance model
  • Urban-scale solar analysis

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • General Materials Science


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