Simulation of Tilted Rooftop Photovoltaic Panels at City Scale: Novel Measurements, Model Development, and Application in WRF

Rooftop photovoltaic (PV) panels alter the urban energy balance and affect local climate. However, the use of simplified PV models and models lacking thorough evaluation against observational data has resulted in conflicting conclusions related to their local climate impacts. Here, we further develop a rooftop PV energy balance model, UCRC-Solar, and couple it to the multilayer urban canopy scheme BEP-BEM in the Weather Research and Forecasting (WRF) model. Model extensions include updated radiative and convective energy exchanges between both sides of the PV module and the atmosphere/roof surface. We conduct a year-long measurement campaign in London, Canada, to provide a comprehensive meteorological and energy balance data set for an array of tilted PV panels on a flat roof. The upgraded UCRC-Solar is evaluated extensively against this newly collected PV module surface temperature and electricity production data, both offline and online. Coupled mesoscale WRF simulations for Toronto, Ontario, showcase the impacts on urban climate from different configurations of rooftop PV models. UCRC-Solar with tilted panels shows the most notable daytime warming ($\sim 1.0°$C) and the least nighttime cooling ($\sim 0.4°$C) of the near-surface air temperature, followed by UCRC-Solar with flat panels, and finally, the existing WRF PV model, which yields more cooling. Unlike previous work at this scale, our approach includes all relevant physical processes and rigorous model evaluation for extended periods across different locations. Furthermore, the updated UCRC-Solar in WRF permits panels with any tilt, which has not previously been available at this scale.