This study aims to develop a methodology for upscaling commercially available latent thermal energy storage systems using salt-hydrate HS48 as a phase change material, with a focus on determining optimal design parameters for different sizes and energy demands. The paper begins with a comprehensive review of phase-change materials' properties, theories, and practical applications in various energy storage systems, including integration into hot water storage tanks with diverse configurations. Subsequently, a research method is introduced, based on heat transfer principles and commercial heat battery specifications, providing a scalable simulation model validated through experimental setups. The model emphasizes two different scales and demonstrates non-linear charging time increases with PCM mass. After optimization, the model is scaled to match a commercially available heat battery's power output, evaluating various configurations based on key independent variables. Results favor the configuration, which consist of twice the number of parallel tubes, as the optimal design for reducing PCM mass, system size, and charging time. While the study shows promising outcomes, it also highlights areas for improvement, such as refining assumptions about phase change behavior and addressing specific application requirements like domestic hot water supply