RWE originally envisaged installing 417 turbines in the Channel. However according, this has now been capped at 278. It still aims to reach 1.5GW by installing a number of larger capacity turbines.
The company said the decision was taken following environmental and engineering studies, as well as public consultations.
Speaking about the move, RWE wind farm development manager Robert Thornhill said: "We have reduced the maximum number of turbines for which we will apply for planning consent to build from 417 to 278. There has been no change to the range of turbine sizes we will apply for planning consent.
"These range from 3.6MW to 8MW wind turbines. The range of turbines which we will apply for planning permission for will now be between 188 and 278. We will apply for planning permission for a wind farm with the maximum capacity of up to 1500 megawatts (MW)."
Thornhill added the cap of 278 turbines meant that if the wind farm be built out with 3.6MW turbines the total capacity would be 1000MW, or if built out with 5MW turbines the total capacity would be 1390MW."
Further outline the plans for the wind farm, RWE will be holding events along the south Wales coast in July and August.
When RWE acquired Atlantic Array in 2008, the project was set for 1.5GW capacity. At the time, RWE said its acquisition supported its intention to bid for sites under the Crown Estate's Round 3 leasing programme.
The project was originated by Farm Energy, the company that originated the 1GW London Array offshore project in 2007.