Opponents of windfarms have welcomed the Welsh Government's announcement to restrict developments in mid Wales.
First Minister Carwyn Jones said planning guidelines on the number of windfarms should in future be regarded as an upper limit.
The Welsh Government wants the UK government to devolve powers over large-scale energy generation projects.
Glyn Davies, Conservative MP for Montgomeryshire, said it was "hugely welcome news".
Hundreds of people took part in a demonstration on the steps of the Senedd in Cardiff Bay in May to voice their opposition to the proposed developments.
Dozens of pylons, some measuring 154ft (47m), and a substation are earmarked to connect with about 10 wind farms.
Seven areas of mid and south Wales were chosen for the development of windfarms under a policy known as Tan 8 in 2005.
But the Welsh Government says the number of applications and declarations of interest from developers are higher than anticipated, leading to proposals for major overhead grid infrastructure.
In a statement on Friday, Mr Jones said: "The Welsh Government believes this level of development is unacceptable in view of its wider impacts on the local area."
He said the Tan 8 "capacities should be regarded as upper limits".
Overall responsibility for large-scale energy generation rests with the UK Government.
Mr Jones said he hoped the UK Government would "respect" his announcement and "not allow proliferation when they take decisions on individual projects in Wales".
He added: "My government would not support the construction of large pylons in mid Wales and my ministers are pressing this case with National Grid Transmission and with Ofgem.
"This situation amply illustrates why consents for major energy infrastructure projects must be devolved to Wales.
"We cannot accept a position where decisions made outside Wales will lead to inappropriate development for the people of Wales."
He said he would raise the issue at a meeting of the British and Irish Council on Monday.
Officials said they had listened to the concerns of people in mid Wales where pylons could carry 400,000 volt electricity cables from north Powys to near Shrewsbury, Shropshire.
Myfanwy Alexander, of Llanfair Caereinion, Powys, who helped organise last month's protest in Cardiff Bay, said the announcement was "very, very welcome".
"I also believe, in a way, it's not completely unexpected," she said.
"I don't think when Tan 8 was drawn up they had any idea, to use a cliche, they were opening a Pandora's box.
"They created a system sufficiently slack to allow vast multi-national companies to come in."
She added: "When we went down to Cardiff we were marching in the hope of making our voices heard and I think, in a way, we clearly have."
Glyn Davies, Conservative MP for Montgomeryshire, said: "For me it's hugely welcome news - it's all I could have hoped for.
'Win this battle'
"It's clear that the first minister and the Welsh Government have listened to the people of mid Wales.
"I have now all the ammunition I need to continue this fight in Westminster, and have sufficient encouragement to feel that the people of mid Wales are going to win this battle to protect our uplands."
Alison Davies, chair of Conservation of Upland Powys, said her reaction was "cautious" and the Welsh Government was only now responding to the protest outside the Senedd.
"Although they may be saying they don't want to put pylons on the hills, the choice is not theirs - energy is not devolved," she said.
"This doesn't change the fact that Tan 8 has identified seven areas of Wales for windfarms which the people of Wales object to most strongly, especially so in mid Wales."
Montgomeryshire AM Russell George, environment spokesperson for the Conservatives in the assembly, said ministers had finally "given in to the strength of public opinion on windfarm developments".
"The first minister should now concede that Tan 8, the guidance he is responsible for, is not fit for purpose and is in need of an urgent and thorough review," he said.
Friends of the Earth Cymru said it supported the Welsh Government's announcement.
Neil Crumpton, energy advisor to Friends of the Earth Cymru, said: "We welcome the first minister's ongoing commitment to wind energy and his call for planning powers for energy schemes of over 50 megawatts to be devolved to Wales."