Energy performance optimization of BIPV windows in dust-prone semi-arid climates

Dust accumulation remains a persistent constraint on the energy performance and durability of building-integrated photovoltaic (BIPV) windows in semi-arid environments. This paper assesses a facade-scale system of enhancing the operation of BIPV glazing in dusty and high-irradiance climates by introducing interventions of secondary-layers with protective, optical, thermal, and anti-soiling capabilities. The Smart Health Tower has been chosen as a case study in Sulaymaniyah, and a digital workflow was created with Rhino, Grasshopper, Ladybug, and PVsyst to evaluate the current used system and an extended full-façade baseline. As-built upper-window BIPV installation was initially used in tool-to-reality validation with the simulated annual electricity production of 321,685 kWh/year against the reported 321,000 kWh/year with is a deviation of + 0.21. After validation, the model was then extended to a complete-facade BIPV system featuring an active photovoltaic area of 5,814.6 m². The established no-layer monocrystalline baseline generated 2,478,305 kWh/year and the retained annual improvement were: optical film layer 3.0%, anti-UV/anti-scratch layer 5.8%, modular design logic 6.0%, thermal-resistant layer 8.0%, and hydrophobic coating 13.0%. The LSC based concentrating layer had the greatest projected output, 3,543,974 kWh/year, which is equal to a 43.0% increase over the baseline. These findings show that the performance of BIPV windows in dusty semi-arid environments can be significantly enhanced by means of the design of the secondary-layer at the facade, rather than photovoltaic integration alone. Simultaneously, the research identifies that the baseline case was explicitly validated, but the secondary-layer cases were modelled as literature-based comparative projections, rather completely resolved optical-thermal models. In general, the research adds a facade-based approach to the methodology of improving the energy efficiency of BIPV windows in semi-arid urban environments prone to dust.