Advanced Simulink Modelling of PV–PEM Electrolyser Coupling

Abstract

A higher production rate of green hydrogen is needed to meet climate change targets. This thesis investigates the behaviour of four photovoltaic (PV) and proton exchange membrane (PEM) electrolyser coupling configurations in MATLAB Simulink. Direct and indirect coupling are simulated, and systems are created with PV reconfiguration, with and without a battery, to investigate the behaviour of systems producing green hydrogen. The systems are built with components available in Simscape an electrical library of Simulink. The core of the models is a validated equivalent electrical circuit (EEC) model of the PEM electrolyser.

The models show that direct coupling is the simplest system with the lowest energy transfer losses, but it can suffer from higher mismatch losses, depending on the local irradiance profile. An optimised indirectly coupled system could reduce those mismatch losses at the cost of increased energy transfer losses. The indirectly coupled system highlights the importance of optimising its control strategy to be able to reduce mismatch losses. With the reconfiguration of the PV modules, the mismatch losses of the direct coupling are reduced, and the overall solar-to-hydrogen (STH) efficiency is improved. To utilise the disconnected PV modules, a battery is added to the directly coupled system with reconfiguration. The addition of the battery lowered the STH efficiency due to increased energy transfer losses inside the battery converter. This is likely due to the simplified control logic of the battery, which leads to low PV and energy transfer efficiencies. The additional battery enables nighttime hydrogen production, which increases the hydrogen availability. Three of the four cases are simulated with a two-day irradiance profile, leading to an STH efficiency of 12.89% for the direct coupling, 15.39% for the direct coupling with reconfiguration and 10.79% for the direct coupling with reconfiguration and storage.

The results demonstrate that the system with PV reconfiguration has the highest STH efficiency, but that the utilisation of the disconnected PV panels needs improvement. Overall, this thesis can be seen as a foundational framework for building circuit level PV-PEM systems using discrete electrical components from the MATLAB Simulink Simscape library. The modelled systems provide a platform for future optimisation and research on component interactions.

Popular Abstract

Electricity generated by photovoltaic panels (PV) using solar energy can be used to produce green hydrogen. In this thesis, simulations are run with varying coupling strategies between PV and proton exchange membrane electrolysers (PEM), using MATLAB Simulink to compare their efficiency. The studied systems include direct coupling, indirect coupling with a converter, PV reconfiguration, and PV reconfiguration with a battery.

The different models were tested over short and long time spans. The results show the behaviour of the system on a scale of seconds as well as on a scale of hours. The direct coupling between PV and PEM is the simplest solution, which does not need a lot of control during operation. But before the system can be activated, the right sizing of the PV and PEM components needs to be found. The direct coupled system is designed for a specific range of solar power, which leads to an unfavourable operation if the solar power varies from the power the system was designed for. Indirect coupling uses a converter between PV and PEM, which allows regulation of the system operation but also leads to energy losses in the converter. With the possibility of regulation, complexity is added to the system, which is why the results showed a reduced efficiency. PV reconfiguration is changing the size of the PV system while producing energy, which needs to be tested before the operation, but it then leads to a wider operating range, so the PV-PEM system can produce hydrogen with a higher efficiency. The PV reconfiguration can be seen as an alternative for regulating the system instead of the converter in the indirect coupling. Adding a battery to the system makes it possible to produce hydrogen during the night or when no sunlight is available. The battery setup in this thesis is rather simple and needs further improvements to its control system to reduce power losses and be an efficient add-on to the hydrogen production.

The developed models can be used for further testing of components or as a starting point for varying PV-PEM systems. Such models are needed to possibly reveal problems before building real systems, which can save money and time. The setup of the simulations in Simulink has the benefit of displaying the PV-PEM systems as electrical circuits, which are relatively easy to interpret.

Research on green hydrogen production is not only important for replacing industrial fossil based hydrogen, but also for exploring the possibility of hydrogen as an energy carrier. In that way, hydrogen can store energy over a long time span.

• author: Wöhlert, Hanna Phoebe
• supervisor: Diamantis Almpantis
• organization: Department of Energy Sciences
• course: MVKM05 20261
• year: 2026
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Simulink, Photovoltaic, Green Hydrogen, Proton Exchange Membrane Electrolyser, Equivalent Electrical Circuit, Coupling Strategy
• report number: LUTMDN/TMHP-26/5681-SE
• ISSN: 0282-1990
• language: English
• id: 9245403
• date added to LUP: 2026-07-02 09:08:02
• date last changed: 2026-07-02 09:08:02