Risk analysis of coupled PV-electrolyser systems

Renewable Hydrogen is seen as the trail blazer for reaching the decarbonisation goals in 2030, 2050 and beyond. The share of renewable hydrogen production globally is below 1% of the hydrogen produced. To guarantee large-scale implementation, reliability of coupled PV-electrolyser systems was investigated via a risk analysis. Four set-ups for coupled PV-electrolyser systems were examined by fault tree analysis. Failure probabilities ranged between 0,028 and 30.04% depending on system size, components, and topology. It was found that reliability depends significantly on the redundancy of the components. Most critical components were PV-inverter with about 20% of the risk share and air blast cooler, gas treatment and compression and water treatment which accounted on average for 75% of the risk share. The evaluation was done for failure probability as well as for hydrogen-cost weighted risks. In all systems redundant design of components as e.g. inverter increases the reliability of the overall system (approx. 10%). Using several inverters reduces the hydrogen cost weighted risk at about 60%. The electrolyser system incorporates a higher probability of total system failure compared to the photovoltaic system. Measures to decrease the rated levelized cost of hydrogen are more difficult to apply at the electrolyser, due to a more sophisticated system build up.