Critical assessment of large-scale rooftop photovoltaics deployment in the global urban environment

In support of the clean energy transition, rooftop photovoltaics (RTPV) deployment has been globally advocated, enabling citizens as energy prosumers within their localised building environment. However, the effectiveness of RTPV implementation is influenced by diverse bioclimatic conditions. Here, we provide a critical climate-related RTPV characterisation across the globe, consisting of a comprehensive assessment of RTPV performance, taking into account global horizontal irradiation (GHI) and local environmental parameters, including space conditioning requirements in different climatic zones. Additionally, we examine the technological advancements aimed at improving efficiency in RTPV systems. Within a meta-data analysis, we find that the RTPV systems offer various advantages in terms of building overall energy performance, particularly in moderate and warm climates. We observe that typical or increased insulation values can offset the RTPV effect in uninsulated roofs. This is essential in regions with cold climates and helps to mitigate increased heating requirements during winters or higher cooling demands during summer nights. A relationship between the ratio of building space coverage to PV surface and GHI is proposed for lowenergy buildings to calculate the space requirements for achieving net zero buildings, globally. Moreover, in hot climates, cooling the RTPV surfaces can enhance efficiency by up to 20 % and increase power output by up to 15 %. By advancing RTPV efficiency to 30 % with emerging technologies, the decarbonisation of high-rise buildings can be facilitated, alongside energy efficiency and RTPV implementation measures. Striking a balance between thermal insulation needs, we conclude that RTPV offers wide benefits across different climatic conditions.