This research evaluates the economic feasibility of adding offshore solar farms (OSFs) to planned offshore wind farms (OWFs) in Europe, identifying feasible ranges of OSF and subsidy levels to reach economic feasible projects. Ultimately, this leads to conditions to reach economically feasible projects for adding OSFs to OWFs. Using shared infrastructure, such as the power export infrastructure (PEI), it reduces the need for offshore grid expansion and lowers initial OSF investment costs. This study addresses a gap by examining the economic feasibility of this integration, specifically through an economic added value (EAV) analysis, combined with various OSF cost scenarios through a net present value (NPV) assessment.

First, a literature review explores the economic and technical benefits, focusing on shared OWF infrastructure and identifying relevant stakeholders, when adding an OSF. A techno-economic model is developed to calculate the economic added value based on increased OSF revenues and the added value subsidy (AVS), which reflects cost savings from using shared infrastructure. Subsequently, the model is applied to two OWF case studies, a wind farm site in the Netherlands and wind farm site in Italy, where economic feasibility is evaluated.

This study concludes that the addition of an OSF to an OWF at the Italian site is economically feasible, when an optimistic OSF cost scenario is used. With less optimistic OSF cost scenarios, the the addition of an OSF to an OWF would require higher AVS from increasing shared infrastructure costs to become feasible. The integration of OSFs shows greater economic potential in southern Europe, particularly in regions such as Italy, where abundant solar resources and a lower wind potential contribute to a higher EAV per unit of OSF capacity because of substantial growth of the PEI capacity factor. Locations with lower initial OWF capacity factors, greater increases in additional OSF capacity factors, and high shared infrastructure costs lead to faster NPV improvement and reduced dependence on subsidies, representing economically favourable conditions for adding OSFs to OWFs.