This paper examines the techno-economic feasibility of utilising salt caverns for large-scale hydrogen storage in Ireland, leveraging wind energy and proton exchange membrane (PEM) electrolysers. The analysis focuses on optimising the integration of wind power with hydrogen production and storage, addressing key challenges such as energy curtailment, grid transmission constraints, and renewable energy intermittency. Findings highlight significant economic considerations, with a single hydrogen storage cavern requiring an initial investment of approximately €240 million, where geological site preparation and compressor systems constitute the largest cost components. Annual operational expenses (OPEX) are estimated at €4.6 million, largely due to compressor energy consumption and cooling requirements. The study emphasizes the critical impact of electrolyser scale on economic viability. Small-scale systems, such as a 20 MW PEM electrolyser, are economically unfeasible, with a levelised cost of hydrogen (LCOH) of around €10/kg and filling times extending up to 2.5 years. However, scaling up to a 200 MW PEM electrolyser dramatically improves cost efficiency, lowering the LCOH to approximately €0.83/kg and reducing filling times to just 90 days. This research provides a comprehensive framework for hydrogen storage development, offering key insights for policymakers and industry stakeholders to drive the renewable energy transition and enhance energy security through cost-effective and sustainable storage solutions.