Hill farmers in the Swansea Valley claim they could get just £200 compensation a year for putting up with 400ft high wind turbines.
Around 100 farmers have historic grazing rights on the common
They say agents acting for the Duke of Beaufort, who owns Mynydd y Gwair Common between Swansea and Ammanford, have indicated about £20,000 will be available annually to compensate the 100 farmers with historic grazing rights to the land.
No formal offer has been made but members of the commoners association say they will fight the plans for the 23 turbines no matter how much money is put on the table.
Many have joined an action group - Save Our Common Mountain Environment - which plans to step up its campaign anticipating a formal planning application later in the year.
David Rowlands, of the local commoners association, said: "It has been indicated that about £20,000 will be offered not to the farmers but to the association.
"There are about 100 farmers grazing cattle and sheep there so it is nothing to them.
"They want us to take the animals off the common while it is being built.
"There have been grazing rights to the common for generations.
"It will not only affect us while it is being built. When these are working how are we expected to work a sheep dog around the noise.
"The animals are not going to stay around once they are running.
"The commoners association is against this and the action group will be stepping up the campaign."
If the formal planning application is for 23 turbines as indicated by the Somerset Trust, which is acting on behalf of the Duke of Beaufort, then councillors in Swansea will be asked for their views.
But the application will be determined by the Department of Trade and Industry unless campaigners can force a public inquiry.
The trust says any deal between itself and the farmers is confidential.
Representatives have met with the farmers and stressed that farming interests - in terms of the numbers of stock they could graze on the land - would not be affected.