HIGHER-ORDER MODAL DECOMPOSITION OF URBAN IRRADIANCE VARIABILITY IN SPACE AND TIME

Three-dimensional urban structures cause unwanted variations of incident solar radia- tion spanning various spatiotemporal scales. The applicability of higher-order modal decomposition for the detailed analysis of the solar resource variability in intricate built areas is explored. The annual irradiance on a cubic building located at the centre of a theoretical district granted structural hetero- geneity is estimated with a backwards Monte Carlo method. The latter is arranged as a three-way tensor from its a priori known temporal characteristics and decomposed via Tucker Higher-Order Sin- gular Value Decomposition (HOSVD). Dominant spatial and temporal (daily and seasonal) modes of variation are extracted and ranked by order of influence, helping the identification of variability-prone façade regions. Information about daily and seasonal periods of high irradiance variability is obtained, and related changes in its spatial distribution are educed. Disruption to the direct radiative component by prominent surrounding geometries is especially portrayed.