A council is being advised to oppose plans to expand a wind farm in the Lammermuir Hills – taking its turbine total to more than 100.
A report by Borders planning officers said aviation lights would give the Crystal Rig scheme an “industrial appearance” and make it “incongruous”.
Developers Fred Olsen Renewables want to add another 11 turbines to the site.
It has described the area as the “ideal location” to help meet national renewable energy targets.
The original 25-turbine Crystal Rig development became operational in 2003 and was the largest onshore wind farm in Scotland at the time.
Sixty more turbines were completed in 2010 with another six added in the third phase of the project which straddles the boundary between the Scottish Borders and East Lothian.
The latest phase would see 11 turbines constructed – some of them 200m (about 650ft) tall.
Seven of them would need red aviation lights fitted which has prompted advice to councillors to object to the plans.
A planning report to Scottish Borders Council said the lighting would be “incompatible” with the visual amenity of the “dark rural environment largely unaffected by artificial light”.
It advised the local authority to object to the expansion but the decision on whether it can proceed will be made by the Scottish government.