Adaptive co-planning of building-integrated photovoltaics and vehicle-to-grid infrastructure under phase-out policy incentives: A two-stage multi-objective optimization framework

The synergistic deployment of Building-Integrated Photovoltaics (BIPV) and Vehicle-to-Grid (V2G) systems faces a critical challenge: the phase-out of Feed-in Tariffs (FiT) fundamentally alters the techno-economic coupling of energy assets. Existing static models fail to capture this policy-induced regime shift, risking suboptimal sizing and asset stranding. To address this issue, this study proposes a policy-adaptive, two-stage multi-objective optimization framework integrating BIPV capacity planning with V2G sizing and scheduling. Applied to a Hong Kong case study, the framework demonstrates that an aggressive BIPV strategy, combined with balanced V2G operation, reduces lifecycle costs by 17.43%, carbon emissions by 21.21%, and net load standard deviation by 15.42%. Crucially, comparative analysis indicates that V2G can offer a more cost-effective alternative to stationary energy storage systems (ESS): utilizing commuter EVs as a low-marginal-capital buffer achieves comparable grid stabilization. To mitigate early-stage investment risks, the study advocates a modular, phased deployment roadmap. Furthermore, the system dynamically adapts its operational logic, transitioning from grid-decoupled arbitrage during the FiT regime to a grid-coupled, solar-following mode after the policy expires. Ultimately, this study delivers a highly adaptable BIPV-V2G co-planning framework, enabling stakeholders to derive customized, policy-resilient decarbonization strategies across diverse urban contexts.