New powers over energy for Wales have been delayed at the request of the Welsh government, opposition parties have claimed.
They include control over fracking and the ability to consent to larger schemes.
The Conservatives and Plaid Cymru accused Welsh ministers of "refusing to take responsibility".
But the Welsh government said the timetable for transferring the new powers was "as originally agreed".
The Wales Act devolves extra powers over transport, electoral arrangements and income tax rates as well as energy from Westminster to Cardiff Bay.
But it has emerged that the Welsh Government has asked for fracking powers to start six months later in October 2018, and consent over energy schemes up to 350MW a full year later in April 2019.
The extra time is needed for "transitional arrangements to be put in place", a spokesperson said, adding that the postponement had been agreed with the Welsh Secretary Alun Cairns.
But Plaid Cymru's energy spokesman Simon Thomas said he was "amazed" at the situation.
"In Wales we won't be getting further powers on electricity generating stations of 350MW until April 2019 because the Labour Party is too timid when it comes to devolution."
"The people of Wales are ready for these powers but the Welsh government is once again holding our potential back."
The Welsh Conservatives said there was "chaos at Cathays Park" and that the Welsh government was "simply not ready" for these powers.
Speaking to BBC Wales, Energy Secretary Lesley Griffiths said "a huge amount of work" had been carried out in preparation for the new responsibilities.
"The impression is that we've been sitting around doing nothing - that is absolutely not the case."
"When we found out that we were having these powers through the Wales Act, we had an agreement with officials and ministers in Westminster that we wouldn't have them until 2019 when we would be ready."
Wales generated 38.8 TWh of electricity in 2016, of which 82% was from fossil fuels and 18% from renewables.
However, electricity generation from renewables has grown rapidly, doubling in the last five years.
Much of the energy produced in Wales is exported to the rest of the UK.
43% of Wales's electricity consumption in 2016 came from renewable sources - up from 32% the previous year.
The Welsh Government wants to see 70% of the country's energy coming from renewables by 2030.