Shell said projects in the US offered more competitive returns
German power firm E.On and Danish utility Dong have bought Shell's stake in the London Array wind farm, which is set to be one of the world's largest.
E.On and Dong were originally Shell's partners in the 341 turbine project and will now each own half of it.
The planned 1,000 MW project could power as many as one quarter of London's homes.
Shell said in May it would sell its stake in the farm in the Thames Estuary and focus on wind power in the US.
It said that US government incentives offered Shell "competitive returns".
The costs of the London Array project are reported to have spiralled, with turbine components rising particularly quickly.
The price paid for Shell's stake in the project has not been disclosed.
The two remaining partners have not yet made a definite decision to proceed with the wind farm, but E.On hopes that decision will be made later this year.
"We hope to be able to keep the project on track and we should be able to complete the first phase by the end of 2012," said Paul Golby, chief executive of E.On UK.
But a statement from Dong Energy was more cautious, saying: "No investment decision has been made by Dong Energy regarding the project".