The transition to a net-zero economy with increased electrification of transport and heating poses electricity supply challenges during the winter months, particularly in PV-dominated systems. This study explores comprehensively various strategies and their combinations to address potential winter electricity deficits in Switzerland. Our innovative modelling integrates three sectors (electricity, heat, and transport), neighbouring countries, and environmental life cycle considerations. Among potential strategies to mitigate Swiss winter electricity deficit, electricity imports from neighbouring countries are taken as the benchmark policy strategy. Our analysis reveals that only gas-fired power plants and alpine PV, if applied in isolation, are technology options that alleviate the Swiss winter deficit and reduce cost at the same time. Increasing other single power technologies individually, or importing hydrogen, alleviate the deficit, too, but they inflate energy system costs by 18%–34% compared to relying on electricity imports. Despite the strategies for mitigating the winter deficit assessed being substantially different, our study found no significant environmental concerns regarding local land requirements or critical raw material needs. However, each strategy might imply the need for certain fuel imports and can have a profound impact on determining cost-optimal heating strategies for buildings. With an additional 1.4 GW of gas-fired power plant fuelled by domestic bio-methane, 4 GW of alpine PV, 2.2 GW of wind turbines, and no cost increase compared to its current roadmap, Switzerland could have a fully renewable energy system with a reduced winter deficit and no fuel imports.