The council also voiced concern over the impact on local roads of transporting the 115m high turbines to the site at Waun Garno, Llawr y Glyn.
The proposed site is in an area earmarked for potential wind farm development under the Welsh Government’s controversial current planning policy.
The developer, the UK subsidiary of the Spain-based Acciona Group, planned to put up 11 turbines each rated between 1.5 and 2.3 megawatts.
A statement from the company said: “We are naturally disappointed at the decision not to grant planning approval for the Waun Garno wind farm. We will now carefully review the grounds for this decision and consider our options going forward”.