The Paris Agreement of 2015 has increased the demand for renewable energy sources. The Dutch government plans to exploit the North Sea as its green power plant by implementing 3 GW of offshore solar (OS) energy in existing wind parks. The complementary nature of wind and solar results in more clean energy at a constant power rate. By pooling the power infrastructure of the offshore wind farms (OWF), only a short power export cable (PEC) from the OS system to an OWF transformer is needed to plug in the OS system.

This study aimed to address a research gap in operational conditions for OS systems by exploring how to perform a PEC pull-in on an OS farm. Power cable pull-in operations are normally performed on monopiles of OWTs and, more recently, on floating OWT foundations. However, pull-in operations at sea-surface level, directly at the ocean surface, are not common, especially on systems that act like enormous blankets on the ocean surface. The Oceans of Energy OS farm was used as a case study, representing a novel floating system that behaves like a large blanket and moves directly with the waves at sea-surface level.

The need for an integrated pull-in equipment design was addressed by applying a double diamond design cycle. According to the design methodology, the research first focused on mapping the limits of the OS system. Firstly, a large-scale OS system description was given to understand the relevant aspects of the OS system. This resulted in the hang-off floater location, at which the PEC is pulled in and terminated. Secondly, the hang-off floater was described from a more local perspective to define the requirements.

The requirements were found by analysing and calculating the OS system boundaries and by consulting experts in marine operations. Calculations were done to determine the submerge limits of the hang-off floater, resulting in a limiting external force. The analysis identified the critical steps in the pull-in procedure, which were applied to a force analysis on the relevant PEC segment. This force analysis led to the limiting forces needed for the design of equipment. Together with the advice from experts, this effort resulted in a statement of requirements.

By applying the second part of the design methodology, the design of the equipment resulted in an A-frame. It proved to be a feasible design, as it is commonly used in offshore marine operations. By performing internal force calculations, multiple design choices were addressed and validated. The design proved to be ideal for integration with the OS system; therefore, future iterations towards a final design were provided.

The integration of the A-frame proved to be feasible based on the force analysis. To find out whether the operational challenges of the OS system could be tackled, the offshore operations were considered. By design, the A-frame consists of multiple 20kg pieces, which can be carried to the hang-off floater from a boat landing. In order to verify the design, the equipment installation and the PEC pull-in procedure were described.

In conclusion, this research addressed the unique challenges of power export cable (PEC) pull-in operations at sea-surface-level offshore solar (OS) systems. Unlike fixed or stable floating offshore wind turbines (FOWTs), OS systems require lightweight, modular equipment for safe deployment and retrieval in dynamic conditions. The study demonstrated that A-frames, widely used in offshore operations, can also be adapted for PEC pull-ins on large-scale OS systems in shallow waters. Clear design boundaries and requirements were established to guide future equipment development. The applied design methodology clarified operational limits and provided a starting point for refining pull-in equipment for OS systems.

For future work, it was advised to address the detailed design of the equipment integration to the floater. Also, the material choice was addressed to create weight savings for a more efficient operation. Further recommendations suggest inputs for a model that links parameters to requirements, to address future projects in environments other than the North Sea.