Cost Analysis for a Small-Scale Hybrid, Hydrogen-Based PV Energy System

The achievement of a carbon-neutral society, set as a goal for the next few decades, goes directly hand in hand with the need for an energy system strongly based on renewable energies [1]. However, renewable energies are of intermittent nature and underlie seasonal fluctuations. Sufficient seasonal energy storage capacity is needed for large parts of the world, where specifically hydrogen is seen as a promising solution. Such an energy system, designed exclusively for renewable energies and based on hydrogen, is the subject of this research work. The focus of the study is on a small-scale energy system for private households. The energy system was designed for fully covering the yearround energy demand to minimize grid use. The electricity is generated by a PV system and temporarily stored in a hybrid energy storage system consisting of a hydrogen conversion unit with a long-term storage capability attached and a lithium-ion battery. The costs of such a system are particularly difficult to calculate due to a wide range of influencing factors: Besides energy demands and load characteristics according to the use cases, the location also plays a significant role. This work analyses the influence of various factors such as the choice of location and different cost development scenarios on the total costs and also gives a cost comparison to other system variants without a hydrogen unit. In addition to the cost composition, the cost developments up to 2050 are also presented based on various scenarios. A household energy system developed in Matlab/Simulink is used for the investigation. In addition to the high resolution of the input data, a unique lifetime analysis method was integrated into this model, which enables a very realistic investigation with a high degree of accuracy. The lifetime of the components and their degradation, which influences the hydrogen production (from electrolyser) and hydrogen demand (from fuel cell) heavily has an impact on the cost of the whole system and should therefore be considered.