Residents opposed to Stage 3 of the Hallett Hill wind farm have had a win in the Supreme Court.
The case now will go back to the Environment, Resources and Development Court, in light of new evidence showing unacceptable levels of noise from Hallett Hill Stage 2.
Bill Quinn, from Mt Bryan, says he's "very happy" with the outcome after a "hell of an emotional rollercoaster ride … up, down and around".
"The bottom line is, Stage 2 does not comply with EPA guidelines," he said.
AGL Energy confirmed 16 of the 34 turbines have been shut down at night since December.
Power development general manager Scott Thomas said the company was working with the turbine supplier on a "permanent acoustic treatment" to dampen tonal noise.
"The wind farm will resume normal operation once the treatment has been implemented," he said.
In response to complaints, AGL engaged a specialist noise consultant and found "some audible tones under certain conditions" pushed noise levels over the limit.
EPA guidelines state that tonality can increase the adverse impact of a given noise source, so predicted wind farm noise levels must be adjusted accordingly.
The Mt Bryan residents are concerned that noise testing and monitoring for Hallett 2 had not picked up the issue of tonality, so it may also be a problem for Hallett 3.
Development consent for the Mt Bryan wind farm (Hallett 3) was granted in mid-2009.
Mr Quinn appealed against the decision in the ERD court and then the Supreme Court. His brother, barrister Peter Quinn, says the case is relevant to all Australian states currently applying SA EPA wind guidelines.