In pursuit of the 2050 decarbonisation goals outlined in the Paris Agreement, the European Union aims to integrate renewable energy sources into electricity generation. However, the intermittent nature of solar and wind energy presents challenges for grid stability and reliability. Hydrogen (H2), particularly "green H2" produced through renewable electrolysis, has emerged as a promising energy carrier to complement variable renewable energy. This study investigates the technical and economic feasibility of utilising excess heat generated during Proton Exchange Membrane (PEM) electrolysis, a by-product typically underutilised, to improve the overall efficiency and cost-effectiveness of green hydrogen production. Using Aspen Plus, the study models five heat recovery scenarios: electricity generation via an ammonia Organic Rankine Cycle (ORC), direct heat supply to a District Heating (DH) network, steam generation using hydrogen and electric boilers, and a combined DH and steam generation configuration. The base case assumes no heat recovery and relies solely on cooling towers for heat rejection. Among the alternatives, the DH scenario proved to be the most economically viable, achieving a Net Present Value (NPV) of <euro>9.5 million, an Internal Rate of Return (IRR) of 0.23, and a Payback Period (PB) of 7 years, at a hydrogen price of <euro>9.5/kg. In contrast, the ORC scenario yielded a negative NPV and a payback period exceeding 30 years, indicating limited viability under current conditions. The results highlight the importance of integrating low-grade heat recovery into green hydrogen systems. Redirecting PEM excess heat to existing DH infrastructure offers the most immediate economic and technical benefits, contributing to more efficient, circular, and financially attractive hydrogen production systems.