Bottom-up energy transition through rooftop PV upscaling : remaining issues and emerging upgrades towards NZEBs at different climatic conditions

In supporting the phase-out of the fossil fuels, Roof Top Photovoltaic (RTPV) deployment has been adopted worldwide as an important step of a bottom-up driving pathway of citizens' transformation to become net energy producers within the community of their localized building environment. However, the diverse bioclimatic conditions of this environment may affect the best RTPV implementation. This is facilitated by climate-related characterization and regional adaptation. Hence, the built environment globally as a function of the global horizontal irradiation (GHI), the local environmental parameters of the different climatic zones and the associated technological developments are surveyed. In this work, we have critically assessed the RTPV effect on the building's overall energy performance and found beneficial over a diverse range of moderate and warm climates. By applying adequate insulation beneath the RTPVs, the increased heating needs in winter in cold climates or higher nighttime cooling needs in summertime can be avoided. To design low-energy buildings, we propose an analytical framework based on the space energy coverage by RTPV and the global horizontal irradiation. Moreover, RTPV cooling at elevated temperatures improves the efficiency up to 20 % and increases the generated electricity up to 15 %. Increasing the RTPV efficiency with emerging technologies could extend the decarbonization of high-rise buildings with energy efficiency and RTPV measures. To accelerate the clean energy transition, rooftop PVs should be widely adopted for sustainable solar building applications. Combined with electrical storage, this will allow renewable energy resources to cover a large fraction of future building energy needs worldwide.