Sourcing Continuity and Manufacturer Renewal in Distributed Solar Supply Portfolios

Renewable energy supply chains must balance sourcing continuity and changing manufacturer options. Using 3.52 million U.S. distributed-solar projects, we reconstructed quarterly manufacturer-use portfolios to examine subsequent renewal. We estimated pooled fractional-logit, within-installer linear fixed-effects, and Mundlak fractional-response within–between models. Pooled continuity was associated with lower entrant share and entrant volume share and higher incumbent retention. Conversely, a one-standard-deviation within-installer increase in continuity was associated with a 4.85-percentage-point higher entrant share in 2012–2019 and a 12.85-point higher share in 2020–2023, using the same legacy reference scale. Mundlak estimates showed positive within-installer and negative between-installer entrant-share associations. First-observed entry, non-cumulative Jaccard persistence, and outcome window identity coverage restrictions supported the entrant-incidence pattern. However, the strictest historical timing estimate was imprecise; volume allocation and retention were less stable; and period interactions were specification-sensitive. These observational results distinguish accumulated manufacturer-use persistence from later portfolio change without identifying causal mechanisms or directly measuring resilience or sustainability performance. Joint evaluation of continuity and renewal can improve descriptions of supply-base evolution in renewable energy settings.