The article delves into the challenges faced by incumbent electrolyser original equipment manufacturers (OEMs) in scaling up production capacity to meet the anticipated surge in demand for green hydrogen in the upcoming decade. With a focus on alkaline and PEM electrolysers, which are already in use in industries like chlor-alkali manufacture, the article highlights the need for significant technological evolution to adapt these electrolyser products to the demands of large-scale green hydrogen production. The pace of innovation in alkaline and PEM electrolysis has been swift, leading to cost reductions and efficiency enhancements. Notable changes include the transformation in stack architecture, advancements in manufacturing methods, and the shift towards using more cost-effective and widely available materials. These developments are crucial for the successful scale-up of green hydrogen production and signify a positive outlook towards addressing the challenges in the industry.