ENVIRONMENTAL STRESS–PERFORMANCE COUPLING IN PEROVSKITE BIPV: OPERATING-REGIME TRANSITIONS UNDER SEMI-ARID OUTDOOR CONDITIONS

Abstract

The outdoor performance of perovskite-based building-integrated photovoltaics (BIPV) is a function of the combined effect of solar irradiance, temperature, relative humidity, module architecture, and progressive changes in material state. However, typical techniques assess environmental sensitivity over short time windows or aggregated performance indicators, and therefore have limited ability to identify transitions between different outdoor operating regimes. In this work, we investigate the environmental stress–performance coupling of two independently operated perovskite BIPV modules installed under semi-arid outdoor conditions in Peshawar, Pakistan. Electrical and environmental variables like voltage, current, operating power, irradiance, ambient temperature, relative humidity, and sunshine duration were recorded using a synchronized IoT-based monitoring framework. The analysis employs a continuous, matched, daily observational dataset over the autumn-winter transition and comprise a 300 cm² multi-cell configuration (Module A) and a 500 cm² single-module configuration (Module B). The results indicate a significant seasonal reduction in the environmental operating envelope. Irradiance dropped from about 49–60 mW cm⁻² in October to 32–35 mW cm⁻² in December, and relative humidity increased from about 25–36% to 65–66%. Although the irradiance partially recovered in January to about 35-37 mW cm⁻², the system did not recover to earlier levels of performance. The performance degradation and environment sensitivity of Module A was much more severe than that of Module B. The efficiency loss per month was from 4.4% to 2.3% for Module A while that of Module B was from 7.2-7.3% to 6.1%. This divergence was despite common outdoor exposure, suggesting a large architecture- and state-dependent component in the environmental response. This behavior is consistent with a transition from a regime of operation controlled by irradiance under higher radiation and lower humidity conditions to a regime limited by humidity and constrained by stability during winter. This interpretation is consistent with the known sensitivity of metal halide perovskites to moisture, oxygen, thermal cycling, ion migration, interfacial reactions and poor encapsulation. “Outdoor testing of perovskite BIPV should move beyond simple reporting of overall efficiency and include environmental sensitivity analysis within context of the architecture and explicit identification of switching between operating regimes.” Therefore, the experimental framework allows to separate short-term variability due to weather conditions from the performance limitations of emerging BIPV systems that are conditioned by the environment.