This deliverable presents the results from the assessment of existing array level operation, maintenance and control methods and tools. Potential sources of knowledge for this are the onshore and offshore wind industry and the offshore oil and gas industry. Offshore wind farms face very similar challenges with respect to foundations, submersed electrical systems, personnel and vessel access to array devices, transport of materials, etc. The offshore oil and gas industry has worked with floating or bottom fixed concrete and steel structures for several decades. Main experiences analysed here are related to corrosion problems and long-term stability of mooring systems. Control and operational strategy aspects were also assessed

This report presents the evaluation according to costs estimation of different maintenance strategies