The 20-megawatt Royalla solar farm will be built on land beside the Monaro Highway in Tuggeranong, bounded to the west by the Rob Roy Nature Reserve.

Mr Corbell said it ''will deliver a substantial public benefit'' in justifying his approval.

''The solar farm proposal will contribute to a reduction of around 560,000 tonnes of carbon emissions over 20 years, generating the equivalent amount of energy to power 4400 Canberra homes,'' he said. ''The Royalla solar farm will directly contribute to meeting the greenhouse gas emission reduction targets set by the ACT government.''

But the development, expected to begin later this year, has been the subject of objections from Royalla residents across the NSW border with ''hundreds'' of properties overlooking the 50-hectare site.

''There's a number of us that are only a matter of 100 to 200 metres from the solar farm and the views will be terrible,'' said Jennifer, a long-term resident.

Her property will have views of the solar farm from every paddock and the heritage-listed house.

''It's a most rural vista, it's lovely [and] I think people move out to enjoy a rural lifestyle, never thinking that they'll have 83,000 solar panels in their backyard,'' she said.

''I agree with solar power, but it should be in an industrial area or in an area that does not impact on residents' houses, that's our main concern.''

''We object to the fact that Mr Corbell, when he announced it, said it would not be seen by any residential houses and would have no impact, but he was only referring to ACT residents. It has a huge impact on NSW residents.''

Royalla resident Tim Bloomfield said the consultation process was inadequate and as NSW residents, they have little power over the political process of its approval.

''All it does is build a them-and-us [divide] between the NSW side of the border and the ACT side of the border. Anything that's going to come up in the future, people one side of the border are going to say, 'Well, stuff you','' Mr Bloomfield said.

Mr Corbell said a normal public consultation process had taken place and an independent ''visual impact assessment'' had determined the views from 95 per cent of Royalla homes would be unaffected by the development.

''For a very small number of homes, there will be a low to moderate impact and for that reason I have placed conditions on the approval so that additional plantings will be put in place to help screen the development once it's in place.''

NSW member for Monaro John Barilaro said Mr Corbell's decision to use his call-in powers to approve the development ''defies belief''. ''Noble objectives should not be exempt from proper process,'' he said.

And Royalla residents were not the only ones objecting to the process, with the Conservation Council supporting the aim but also disagreeing with the minster's use of his call-in powers.

''All significant proposals such as this one should go through our environmental and planning approvals,'' director Clare Henderson said.