3D Solar Potential in the Urban Environment: A Case Study in Lisbon

Abstract

The assessment of solar potential in the urban environment is an important instrument for policy decision regarding renewable energy deployment in the city. This paper presents an experimentally validated 3D solar potential model for rooftops and facades from LIDAR data considering anisotropic diffuse irradiation. The data visualization is rendered in the ArcGIS platform using CityEngine to automatically generate 3D models from 2D geometries. The model is validated against summer and winter measurements of photovoltaic performance on a facade. A case study for two densely packed urban areas in Lisbon, Portugal, are presented. Facades are shown to increase the solar potential by 10 to 15%.

Characteristic Declination—A Useful Concept for Accelerating 3D Solar Potential Calculations

“…Considering all these sources of errors, one can estimate a combined uncertainty of %10-25% when estimating the PV yield of complex urban environments, depending on the available data. The upper limit is in line with uncertainty estimates for the tested 3D solar potential model in an urban area in Lisbon, as shown in Brito et al [8] In this context, the relatively small error introduced by considering the monthly characteristic declination, with a significant saving of computational effort, can thus be considered a valuable compromise, especially at low and midlatitudes.…”

“…[ 7 ] It is a complex and computing‐intensive exercise as one needs to calculate the irradiance incident on all available areas on rooftops and facades of all buildings in the urban area while considering the mutual shadow cast by neighboring buildings and trees. [ 8 ]…”

“…To test the applicability of the characteristic declination to the urban context, we have run the solar city model SOL for different urban areas with a wide range of latitudes: [ 8 ] Nairobi (1.3° S), Mumbai (19.1° N), Lisbon (38.7° N), Geneva (42.2° N), and Oslo (59.9° N). For each city, hourly irradiation data for a full year were taken from Meteonorm software (Meteotest).…”

“…[7] It is a complex and computing-intensive exercise as one needs to calculate the irradiance incident on all available areas on rooftops and facades of all buildings in the urban area while considering the mutual shadow cast by neighboring buildings and trees. [8] The application of the concept of the characteristic declination to solar city models has the potential to significantly reduce the computation demand by a factor of 30 as it would allow estimating the incoming irradiation for a whole month by calculating its hourly values for the characteristic day only. Its impact on model accuracy is expected to be lower than the estimation for extraterrestrial irradiation discussed in the previous section due to the fraction of isotropic diffuse irradiation.…”

Utilising Open Geospatial Data to Refine Weather Variables for Building Energy Performance Evaluation—Incident Solar Radiation and Wind-Driven Infiltration Modelling

“…Nonetheless, composed DSMs (of 1 m resolution) have proven up to the task to capture the slope and aspect of basic roof shapes (without variation in the architecture of the roof) required to estimate solar potential on rooftops [31,32]. At least two different 2.5D solar models are previously published detecting vertical façades from 1 m DSM pixels and either estimating wall irradiances under clear-sky [33,34] or based on observations of global horizontal radiation [35]. Another feature of the second model is the inclusion of vegetation which is found to be crucial when modelling irradiance on walls in an urban setting, especially where building heights are relatively low [35].…”