Reshoring silicon photovoltaics manufacturing contributes to decarbonization and climate change mitigation

The study addresses whether reshoring crystalline silicon (c-Si) photovoltaic panel manufacturing to the United States advances climate change mitigation and energy goals amid supply chain fragility. Against the backdrop of COP26 commitments and U.S. objectives for a carbon-free power sector by 2035 and net-zero GHG emissions by 2050, solar PV deployment is rapidly expanding. However, the U.S. has relied heavily on imported c-Si PV modules, primarily from Asia, with shifting trade policies and tariffs. This raises a key question: does reshoring PV manufacturing align with climate targets by reducing life-cycle GHG emissions and energy use compared to offshore supply chains? The study aims to quantify the climate and energy implications of reshoring under current and future U.S. grid mixes and market dynamics.

Prior work has examined reshoring for improving PV product development, delivery performance, cost leadership, and facility siting factors. Studies have also discussed supply chain disruptions, trade protectionism, and the impacts of trade wars on clean energy transitions. However, the direct climate implications of reshoring PV manufacturing—particularly how domestic production interacts with evolving electricity mixes and market shares—have not been systematically quantified. This study fills that gap by providing a comparative and prospective life cycle assessment (LCA) of offshore vs. reshored manufacturing and analyzing contributors such as renewable penetration, technology improvements, and supply chain structure.

The authors conduct a comparative and prospective life cycle assessment (LCA) with a cradle-to-site system boundary and a functional unit of 1 m² c-Si PV module. They define three offshore cases (2010, 2015, 2020) reflecting historical import structures and seven reshored scenarios (2020, 2025, 2030, 2035, 2040, 2045, 2050) reflecting domestic U.S. manufacturing under projected electricity mixes. Key impact metrics are global warming potential (GWP, IPCC 2013 GWP100) and cumulative energy demand (CED). Additional sustainability metrics include energy payback time (EPBT), carbon emission factor, and energy return on energy invested (EROI). LCA implementation uses OpenLCA 1.10.3 with ecoinvent 3.7.1 datasets and OpenLCA LCIA methods v2.0. Supply chain market shares are derived from USITC trade data (HTS 8541.40.6020 for 2010/2015; HTS 8541.40.6015 for 2020). Electricity generation mixes are taken from IEA World Energy Balances for supplier countries (past cases) and from U.S. EIA World Energy Projection System (2021) for future U.S. power mixes (reshored scenarios). Manufacturing stages include silica sand mining; metallurgical, electronics, and solar grade silicon production; crystal/ingot growth (Czochralski for sc-Si, casting for mc-Si, ribbon process for r-Si); wafering; cell processing; and module assembly; ocean shipping is included for offshore imports. The main analysis focuses on manufacturing; operations and end-of-life are discussed contextually but excluded from the formal cradle-to-site boundary in Methods due to data limitations in prior literature. Sensitivity analyses cover: number of suppliers represented (top six vs nine); wafer manufacturing parameters (thickness, kerf loss); and performance parameters affecting EPBT/carbon factor/EROI (solar irradiation, performance ratio assumed 80% with 70–90% range, module efficiency ranges, lifetime, and grid efficiency 30% baseline with 70% upper bound). Future reshored scenarios incorporate increasing renewable penetration in the U.S. grid (e.g., solar and wind shares) through 2050.

• Reshoring impact (2020 comparison): Domestic U.S. manufacturing in 2020 would reduce GHG emissions by 23% and energy use (CED) by 4% versus the 2020 offshore weighted mix.
• Country comparisons (2020): Reshored GHGs are lower than all major suppliers: 30% lower than China, 17% lower than South Korea, 3% lower than Singapore, 18% lower than Thailand. Malaysia’s manufacturing generates ~42% more GHGs than U.S. domestic due to energy-intensive solar grade silicon and crystal stages and a more carbon-intensive power mix. Energy use for U.S. reshored manufacturing can be slightly higher than some suppliers (Singapore 2% lower than U.S., Thailand 1% lower, Vietnam 5% lower), but the weighted average offshore CED remains 4% higher than reshored.
• Future reshored scenarios with renewable penetration: Compared to the 2020 offshore case, U.S. reshored manufacturing reduces GWP by 30% (2035) and 33% (2050); CED decreases by 13% (2035) and 17% (2050). Non-renewable fossil energy use decreases by up to 32%. Transportation contributes ~1% of CED.
• Carbon emission factor and EPBT: Relative to the 2020 offshore case, the carbon emission factor decreases by 31% (2035) and 33% (2050); EPBT decreases by 14% (2035) and 17% (2050). Decomposition (2035): reshoring accounts for 23% of the emission factor reduction and renewable penetration contributes 8%; for EPBT, reshoring accounts for 4% and renewable penetration 10%.
• Past offshore cases: Trade structure shifts led to higher GHGs in 2015 than 2010, primarily due to increased import share from mainland China. Energy use in 2015 also increased up to 10% versus 2010 as supply shifted to South Korea, Malaysia, and Vietnam. Offshore sourcing does not guarantee declining impacts over time.
• Sensitivity analyses: Including top nine suppliers (vs top six) changes CED by <1% and GWP by <2.5%, confirming representativeness. Reducing wafer thickness and kerf losses (slurry sawing, China 2020) can cut CED by 27% (sc-Si) and 24% (mc-Si) and GWP by 29% (sc-Si) and 26% (mc-Si). Increasing grid efficiency from 30% to 70% can increase EPBT by 133% and decrease EROI by 57%. Module efficiency improvements can reduce carbon emission factor and EPBT by up to ~15% and increase EROI up to ~17%. High solar irradiation regions reduce carbon factor and EPBT by ~26%, while low irradiation can increase them by up to ~70%. A 5-year shorter lifetime can increase carbon emission factor by ~20%.
• Life-cycle context: Use-phase and end-of-life GHG contributions are minimal (<0.2% and <0.41% of lifetime emissions, respectively), confirming that manufacturing dominates PV life-cycle emissions.

The findings demonstrate that reshoring c-Si PV manufacturing to the U.S. directly reduces life-cycle GHG emissions and, to a lesser extent, energy use relative to offshore supply chains. The advantages stem from a less carbon-intensive U.S. power mix compared to key exporter countries and from projected increases in U.S. renewable generation. Reshoring also provides resilience against supply disruptions and aligns with policies like the Inflation Reduction Act that incentivize domestic content. Past variability in offshore impacts due to shifting supplier market shares highlights the risk that global trade dynamics can increase emissions and energy use unpredictably. The synergy between reshoring and renewable penetration is central: reshoring delivers the larger share of carbon emission factor reductions, while renewable penetration contributes more to EPBT reductions; both are interdependent because expanding PV manufacturing enables greater renewable electricity shares, which in turn further decarbonize manufacturing. Given that manufacturing dominates PV life-cycle GHGs, the identified reductions meaningfully advance national decarbonization targets.

Reshoring U.S. c-Si PV manufacturing yields substantial and durable climate and energy benefits: immediate reductions versus offshore sourcing (23% GHG and 4% CED in 2020) and larger gains under projected renewable-rich U.S. grids (up to 33% GHG and 17% CED reductions by 2050). The strategy enhances supply chain resilience, aligns with energy policy goals, and supports broader economic and industrial objectives. Technological improvements (e.g., wafering efficiency, module efficiency) and siting in high-irradiance regions can further amplify benefits. Policy support, domestic content incentives, and workforce and infrastructure investments are pivotal to scaling reshored manufacturing. Future research could refine temporal projections, integrate detailed end-of-life and recycling pathways, and assess region-specific siting and grid-integration effects to optimize environmental and economic outcomes.

• Scenario assumptions: Future reshored timelines and U.S. electricity mix projections are assumption-driven and subject to uncertainties in policy, market evolution, technology costs, and grid decarbonization trajectories.
• Trade data proxies: Different HTS codes were used for 2010/2015 vs 2020, requiring proxies for earlier years; market-share representation focuses on top suppliers (validated by sensitivity analysis but still simplified).
• System boundary: The formal cradle-to-site boundary excludes end-of-life in Methods due to data limitations, though use and EoL stages are discussed contextually; BOS components and detailed EoL treatments are not comprehensively modeled.
• Manufacturing detail: Some process parameters (e.g., wafer thickness, kerf loss) are analyzed in sensitivity rather than fully time-resolved in baseline scenarios; regional manufacturing practices and technology mixes may vary.
• Data sources: LCA relies on ecoinvent inventories and IEA/EIA datasets that carry inherent uncertainties; transportation and secondary supply chains beyond top exporters are simplified.