Europe's offshore wind capacity is increasing rapidly, with larger turbines installed further from shore. TenneT proposed an innovative concept, the North Sea Wind Power Hub, in which several farms are connected to an artificial island which has interconnection to surrounding countries. This aims to reduce overall costs, but studies have so far evaluated hypothetical designs rather than the specific system operators’ proposal, and focused primarily on construction costs rather than ongoing system-wide impacts. Here we develop a bottom-up capital cost estimate to compare the Power Hub with conventional point-to-point connection for offshore wind farms. We quantify its consequential impacts on regional electricity prices, the value of wind generation, fossil fuel generation and carbon emissions in 2030 using a pan-European electricity market model. We find that the Power Hub is cheaper if more than 10 GW of wind is built, as the avoided cost of multiple converter platforms offsets the cost of building an artificial island. It has profound impacts on electricity markets across Europe, especially in Britain and Ireland if they gain more interconnection to continental Europe. This impacts the economic viability of wind and gas power stations particularly, and saves 10Mt CO2 per year through reduced curtailment.