Multi-Objective Assessment of BIPV Yield, Complementarity, and Economic Feasibility

Building-integrated photovoltaics (BIPV) are essential for the transition towards net-zero energy buildings, yet a comprehensive multi-regional understanding of how energy yield, temporal complementarity, and economic feasibility interact across diverse configurations remains limited. Task 15 of the International Energy Agency Photovoltaic Power Systems Programme conducted a cross-regional, multi-objective assessment of 357 BIPV design options across eight application types in 44 cities, using a standardized 1 m2 module with efficiencies between 5% and 25%. Energy yields were simulated using climate-specific irradiance datasets, and economic viability was assessed under three price tiers. A multi-objective Genetic Algorithm optimized the azimuths of vertical BIPV based on temporal complementarity and smoothness of the aggregated generation profile with optimal-yield rooftop BIPV system and conventional PV system (BIPV-PV). The combination of rooftop and vertical BIPV demonstrates strong daily and seasonal complementarity, enhancing the stability and continuity of solar energy conversion across time scales. Complementary area-ratio analysis indicates that vertical BIPV surfaces require approximately 1.7–2.5 times more area to match the yield of optimally tilted rooftop BIPV-PV systems. At low BIPV prices, over 90% of configurations become economically viable for efficiencies starting at around 18%, and in some cases even lower. Even at high price ranges, more than half remain viable, highlighting BIPV's increasing competitiveness and cost-reduction potential through improved installation practices and knowledge sharing. Overall, BIPV economic performance depends on complex, interdependent factors, indicating that single measures such as product cost-reduction are insufficient without holistic financial and market integration.