The increasing share of photovoltaic (PV) electricity creates a growing need for storage solutions able to shift renewable energy availability over time and match it with demand. Phase change material (PCM)-based thermal energy storage offers such a possibility by converting surplus electricity into heat, storing it as latent heat, and releasing it when required by the user or process. However, the production of such systems involves material and energy inputs across upstream supply chains, which should be assessed not only in terms of their quantity, but also in terms of their quality. This study investigates a phase change material-based thermal storage system coupled with a PV installation for a case study of an industrial company using the cumulative exergy consumption (CExC) indicator. The analysis follows an exergy-based life cycle assessment (ExLCA) perspective, where the burden associated with the system is expressed through the total exergy required along its supply chain. The results refer to one year of plant operation and consider a baseline scenario, where no thermal storage or PV installation is applied, and a modernized scenario, where these technologies are incorporated and the storage unit is charged primarily using surplus electricity from the PV system. A life cycle assessment model is developed in LCA for Experts software, formerly GaBi, using Sphera’s Managed LCA Content database for upstream process modeling. The elementary flow inventory from the life cycle assessment model is translated into exergy consumption related to energy, mineral, and nuclear resources.