On the cooling energy penalty of urban photovoltaics: a case study in Sydney, Australia

While application of photovoltaic (PV) solar panels as an energy harvesting system becomes more popular, there are significant urban microclimate and energy penalties associated with their large-scale applications. This study evaluated the impact of PV solar panels on urban temperature and corresponding cooling load penalties in 17 representative building types during the two-summer months of January and February in Sydney. We calculated that when 25-100% areas of roofs are covered by PV solar panels, the ambient air temperature may increase by 0.6-2.3 degrees C. As estimated, the application of PV solar panels on 25%, 50%, 75%, and 100% area of roofs can increase the cooling degree hour (CDH) base 25 degrees C by 10.2%-31.7% and 6.2%-19.1% in the coldest and hottest weather stations in Sydney (i.e. Observatory and Penrith), respectively. We computed that this is equivalent to cooling load penalties of around 1.7 and 6.8 kWh/m2 (8-25%) in 17 different types of buildings during the two summer months period. It is estimated that the total cooling penalty by covering 25%, 50%, 75%, and 100% area of roofs for all building types, including residential and commercial buildings per local government area (LGA) in Greater Sydney can range between 0.5-29.6 GW (3.1-3.9%), 1.2-52 GW (4.8-8.0%), 1.3-61.8 (7.5-9.0%), and 1.8-82.8 GW (8.8-12.1%), respectively. It is advised that future advancements in PV technologies focus on both greater efficiency and the demand to increase reflection of wavelengths of light that are not converted into electricity by the PV solar panels.