Evaluation of Solar Radiation Transposition Models for Passive Energy Management and Building Integrated Photovoltaics

Carlos Toledo,Giorgio Bardizza,Ana Maria Gracia Amillo,Antonio Urbina,Jose Abad

doi:10.3390/en13030702

Abstract

Incident solar radiation modelling has become of vital importance not only in architectural design considerations, but also in the estimation of the energy production of photovoltaic systems. This is particularly true in the case of buildings with integrated photovoltaics (PV) systems having a wide range of orientations and inclinations defined by the skin of the building. Since solar radiation data at the plane of interest is hardly ever available, this study presents the analysis of two of the most representative transposition models used to obtain the in-plane irradiance using as input data the global and diffuse irradiation on the horizontal plane, which can be obtained by satellite-based models or ground measurements. Both transposition models are validated with experimental measurements taken in Murcia (southeast of Spain) and datasets provided by the photovoltaic geographical information system (PVGIS) and the National Renewable Energy Laboratory (NREL) for vertical surfaces facing the four cardinal points. For the validation, the mean bias deviation, root mean square error and forecasted skill were used as indicators. Results show that the error rate decreases slightly for clear days. Better results are also obtained by dismissing data with low solar elevation angles so as to avoid shadowing effects from the surroundings in the early and late hours of the day, which affects mainly the performance of the transposition models for west and east surfaces. The results highlight the potential of equator-facing façades in winter time when the received irradiation can be twice as much as the one collected by the horizontal plane. It is also noteworthy that the operating conditions of all façades are mainly low irradiance and medium temperature at these locations.

Highlights

IntroductionOne of the most common technologies for using solar energy is photovoltaics (PV), which, thanks to their modularity, technological improvement and decreasing cost, have evolved and reached maturity at many scales of installed capacity, ranging from solar farms of several megawatt peak (MWp ) to small systems of some kilowatt peak (kWp ) distributed along urban environments where the PV modules can be added, or integrated as a building material into the skin of the buildings
Solar energy plays a crucial role in the deployment of renewable energies
Two well-known and widely representative two and three component transposition models to estimate the in-plane irradiance on tilted surfaces were analysed in order to evaluate their performance on architectural practice and building integrated photovoltaic systems

Summary

Introduction

One of the most common technologies for using solar energy is photovoltaics (PV), which, thanks to their modularity, technological improvement and decreasing cost, have evolved and reached maturity at many scales of installed capacity, ranging from solar farms of several megawatt peak (MWp ) to small systems of some kilowatt peak (kWp ) distributed along urban environments where the PV modules can be added, or integrated as a building material into the skin of the buildings. PV systems integrated in urban structures usually do not follow classical PV system design practices, where, in order to maximise the production, both tilt and orientation angles are optimised. For a more integrated system, adapted to the building architectural design, non-optimal inclinations and orientations should be considered as defined by the orientation and tilt of the façades and roofs

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Results

Conclusion