A plan to create a clean electricity system by 2030 promised by Labour before the election is “immensely challenging” but still “credible” if ministers take urgent action to fix Britain’s sluggish planning system, the energy system operator has said.

Britain could become a net exporter of green electricity by the end of the decade at no extra costs to the energy system under the plans and bills may even fall if ministers make the right policy changes, according to the operator.

The newly formed National Energy System Operator (Neso) put forward the conclusions as part of its official advice to new ministers on how to reach Labour election pledge to decarbonise the power system by 2030.

Fintan Slye, the chief executive of Neso, said: “There’s no doubt that the challenges ahead on the journey to delivering clean power are great. However, if the scale of those challenges is matched with the bold, sustained actions that are outlined in this report, the benefits delivered could be even greater.”

Labour has faced questions over whether the 2030 target can realistically be met. The Neso report said Britain’s regional power networks would need to grow at a pace more than four times faster than in the past decade, while the UK’s high-voltage transmission network would need to be built at twice the rate of the previous 10 years in the next five.

Neso said there would also need to be “urgent action” from the industry, regulators and government officials to reduce the time it took to consent to big projects and overhaul the planning process so that all changes could be delivered “simultaneously, in full and at maximum pace”. Keir Starmer has pledged to “throw everything” at getting the UK to net zero by making sweeping changes to the planning system.

Slye said: “A clean power system for Great Britain will deliver a backbone of homegrown energy that breaks the link between volatile international gas prices; that is secure and affordably powers our homes and buildings; that decarbonises the transport that we take to school and work; that drives the businesses of today and catalyses the innovations of the future.”

Neso said there were two pathways towards the government’s goal that would lead to Britain generating more low-carbon electricity than it consumes each year.

The first route relies heavily on a surge of new renewable energy projects, including plans to more than triple the UK’s offshore wind capacity to 50 gigawatts in the next six years.

The second path calls for lower levels of offshore wind in favour of a greater reliance on nuclear power by extending the life of existing reactors and building new ones within the six years, alongside gas plants fitted with carbon capture technology.

In both pathways the UK will need to double its onshore wind capacity from 13GW in 2023 to 27GW by 2030, and triple its solar power from 15GW to 47GW by 2030. The ambition will also require the market for flexible power demand – typically asking consumers to shift their use from times of high demand – from about 2GW last year to between 10GW and 12GW by 2030.

Under both scenarios, the UK would continue to use gas-fired power stations to generate electricity when renewable or stored electricity is unavailable – but that this would make up less than 5% of the country’s power consumption.

Ed Miliband, the energy secretary, said: “This independent report provides conclusive proof that the government’s clean energy superpower mission is the right choice for the country, replacing Britain’s dependency on volatile fossil fuel markets with clean, homegrown power controlled in Britain.

“The government is determined to ensure the significant reforms to planning and grid we need so we can back the builders and support investors to make this once in a generation upgrade of Britain’s energy infrastructure happen.”

The system operator, which was formerly owned by National Grid, was tasked with setting out a blueprint to meet the government’s clean energy mission by Mission Control, a new body established by Labour to oversee the decarbonisation of Britain’s energy grid by 2030.

The electricity system operator was transferred from the FTSE 100 energy company into public ownership in September. In its new form it is expected to work alongside GB Energy, a public company set up by the Labour government to invest in low-carbon power, to help connect new generation projects to the electricity grid.