The Government has set a goal to achieve a clean electricity grid by 2030, five years earlier than the target under the Conservatives.
But the speed of the transition could mean the UK is forced to pay a premium to secure technology and equipment, the UK Energy Research Centre (UKERC) has warned.
"By going so fast, it's possible that we could, for example, end up paying a premium to gain access to limited supply chain capacities for wind turbines, electrical equipment and construction, or missing opportunities to secure significant 'local content' in the assets that are built," the researchers wrote.
UKERC, based at University College London, brings together researchers from 20 different institutions and is funded by the Government.
Its annual report on energy policy in the UK also said it was unclear whether the Energy Secretary's 2030 plan would actually lead to lower bills, as the Government has suggested.
Rob Gross, the director of UKERC, said there was no definitive answer as to whether energy bills would be higher or lower under the 2030 plans, because of the uncertainty over gas prices.
"We don't know for sure yet how much it will cost to get to clean power 2030 because we are waiting for some of the costs of doing that to be revealed to us," he said.
But he said that achieving the 2030 goal was likely to be cheaper than the status quo if future gas prices are high, whereas if gas prices are low, the benefit would be less clear.
"We can't say for sure what international fossil fuel prices will be in six years time," Mr Gross said. But he added that hitting the 2030 target should "in the long run, deliver us a more stable price environment".
Mr Gross said: "We need more analysis to ensure we can do that as cheaply as possible. Doing that as cheaply as possible is about making sure we can access the kit and the supply chains. It's also about keeping the cost of capital down."
The report stated: "There are policy options that have the potential to reduce electricity bills in the short-term. However, policymakers face significant challenges both in delivering clean power within the timeline the Government desires and doing so in a way that ensures consumers benefit."
Mr Miliband, the architect of the 2030 plan, has pointed to a report from the National Energy System Operator (Neso) to argue that it "can lead to cheaper, more secure electricity for households".
But speaking to MPs on Wednesday, Fintan Slye, the head of Neso, said lower bills were not guaranteed.
"There is the opportunity for policy intervention or policy choices to be made that would reduce bills," he said. "But what we did not set out to do, and what is not our role, is to determine what bills are for consumers. That's a matter of policy."
The Government has been criticised for repeating its promise that the 2030 goal will bring down bills by at least £300 by the end of the decade.
Keith Bell, a professor at the University of Strathclyde, said that one of the biggest challenges of hitting the 2030 goal was "just getting hold of the capacity and skills" to build the wind turbines and cables needed.
"A lot of the order books are full, manufacturing capacity is full," he said. "And then there's also people to deliver projects, including the design work and construction work. Across the electricity sector as a whole in Great Britain there's a shortage."
A Department for Energy Security and Net Zero spokesman said: "Every family and business has paid the price of rocketing energy bills because previous governments failed to invest at scale over many years in the clean, secure home-grown power our country needed, so we have been left exposed to volatile international fossil fuel markets.
"The Government has a plan to make Britain a clean energy superpower so we can end our energy insecurity.
"As shown by National Energy System Operator's independent report, clean power by 2030 is achievable and will deliver a more secure energy system, which could see a lower cost of electricity and lower bills."