Hybridisation of offshore wind farms with floating photovoltaics: Power smoothing and output-demand divergence reduction

Offshore renewables, like their onshore counterparts, are intermittent, which presents challenges for maintaining grid stability and leads to increased balancing costs. The focus of this work is to investigate how the power variability of an operational wind farm can be mitigated and the severity and frequency of its ramping events abated by hybridising it with floating photovoltaic systems deployed in the vast swathes of unused marine space between the turbines. The London Array offshore wind farm is selected as a case study. A novel approach to quantifying the severity of ramping events is developed on the basis of a parameter defined ad hoc, the Weighted Ramping Event Severity (WRES). The analysis is carried out at a high temporal resolution (10 min), which provides more granular insight into short-term power fluctuations. This resolution is enabled by site-specific wind speed data and Solcast-derived solar irradiance inputs. Additionally, the national electricity demand is considered to assess how hybridisation can improve the alignment between the power output profile and grid demand patterns. The results show high potential for power smoothing, with reductions in power variability of up to 20.8 %, depending on the solar to wind installation capacity ratio. Furthermore, the hybrid farm achieves notable reductions in both the magnitude and frequency of ramp rates, while its daily power output profile demonstrates a much stronger correlation with daily electricity demand. These results highlight the multiple benefits than can be obtained by hybridising existing offshore wind farms with floating photovoltaics.