TRNSYS simulation models for solar-hydrogen systems

Abstract

A solar-hydrogen system is a kind of stand-alone power system (SAPS), which can supply low energy dwellings with energy. With TRNSYS (a transient system simulation program) it is possible to perform parametric studies to find possible system configurations for different climates and loads. The systems simulated in this study consist of a photovoltaic (PV) cell array, an electrolyzer, a hydrogen (H₂) storage, a fuel cell, a catalytic burner, a lead-acid battery, DC/DC converters, DC/AC inverters, diodes, a solar collector, and a water storage tank. The main equations for the PV cell, electrolyzer and fuel cell are provided, while the other models are only briefly described. Simulations are performed for conventional low energy dwellings located in northern latitudes and results for different system configurations and operation schemes are given. The results show that the size of the solar-hydrogen system for a conventional low energy house located in Trondheim, Norway (63°N), needs to be quite large. This is mainly due to the somewhat high energy requirements assumed, but also due to the low insolation available. Simulations of the same dwelling located in lower latitudes, in more favorable climates, and/or with lower energy needs (e.g., future dwellings), show how the size of the solar-hydrogen system can be significantly reduced. The study also illustrates the importance of minimizing the thermal and electrical loads before designing a solar-hydrogen system for energy self-sufficient buildings.