Stress Testing Global Import Portfolios for Solar PV Supply Security in Energy Transition: Exposure, Reallocation Space, and Sourcing Persistence

Concentrated solar photovoltaic (PV) sourcing poses challenges for supply security during energy transition. This study examines supplier-country policy conditions, bounded portfolio reallocation, and observed sourcing adjustment within importer-specific trade portfolios. Using PV-related CEPII BACI data for 2017–2024, we analyze 197 importing geographic units, with baseline portfolios constructed from 2017–2019 trade and policy conditions mapped for 2020–2021. Mapped exposure is strongly correlated with China’s supplier share (Spearman ρ = 0.946). Under a 10-percentage-point reallocation budget, 194 portfolios complete the accounting shift without recipient absorption limits. Contribution-ranked reallocation produces a median exposure reduction of 0.034, compared with 0.038 under exposure-minimizing linear programming, but achieves a larger reduction in supplier concentration (0.099 vs. 0.076). Historical absorption bounds substantially restrict reallocation among 76 evaluable portfolios. Mapped exposure is weakly negatively correlated with nominal import value growth (ρ = −0.164; N = 193), but the association is not statistically significant in composition-adjusted regressions. Higher-exposure portfolios also exhibit lower sequential supplier-share reconfiguration across the pre-, focal, and post-periods, although the conditional associations weaken after accounting for China’s supplier share. These findings reveal important differences among measured exposure, portfolio diversification, and observed sourcing adjustment.