To tackle the rising CO₂ emissions from the aviation sector, the European Union has implemented the ReFuelEU Aviation Regulation, designed to accelerate the adoption of Sustainable Aviation Fuel (SAF). Beginning in 2025, aviation fuel suppliers will be mandated to ensure a minimum SAF blend of 2% at EU airports, with the target gradually increasing to 6% by 2030 and 70% by 2050. Of the 2050 target, 35% is expected to be met through synthetic aviation fuels (e-fuels). This regulation is anticipated to reduce CO₂ emissions from aviation by over 60% by 2050 compared to 1990 levels, marking a key milestone in the EU’s overall climate and decarbonization strategy [1]. This study presents a forward-looking techno-economic framework for estimating the production costs of Sustainable Aviation Fuel (SAF) derived from EU-sourced second-generation biomass as listed in the REDII (2018/2001) [2], using solar-assisted fast pyrolysis and solar hydrogen upgrading. The production costs of SAF currently remain higher than those of conventional fossil-based jet fuels. A major contributor to these costs is Capital Expenditures (CAPEX), particularly for SAF production technologies that serve the aviation sector. These costs, along with feedstock expenses, significantly influence the overall economic viability of SAF. Therefore, estimating the potential for cost reduction through research and development (R&D) and cumulative deployment, from first-of-a-kind (FOAK) to nth-of-a-kind (NOAK) production facilities, is essential. SAF production processes typically involve a combination of mature and emerging technologies, each with distinct cost-reduction trajectories. This study adopts a methodological framework based on learning curve theory to estimate cost reduction. The proposed approach employs a multi-component learning curve model [3] that disaggregates the SAF production value chain into major subsystems/units into its technological elements to identify where cost reductions are most likely, using techno-economic data. This bottom-up modelling captures first-of-a-kind (FOAK) to next-of-a-kind (NOAK) cost transitions for scaling scenarios targeting 0,1 Mt SAF production in 2030 and 5 Mt by 2040. The framework incorporates scenario-based analysis to evaluate the effects of technological maturity, deployment scale, and future capacity expansion on production costs. This work supports informed policy and investment decisions to accelerate the deployment of climate-aligned aviation fuels in the EU, highlighting the potential for significant long-term cost reductions in emerging SAF production technologies.