Liz Truss has refused to rule out the prospect of widespread blackouts for up to three hours a day this winter if the country is unable to import enough energy.
National Grid has warned that both households and businesses are at risk of being cut off.
It said a worst-case scenario could include "load-shedding", where power is restricted to different areas at different times to prevent uncontrolled outages.
Homeowners will be asked to use their washing machines and other electricity appliances at night to help avert potential disruption during peak hours. Under other contingency plans, households and businesses could be handed £10 a day to stop using electricity when needed.
Speaking in Prague at a meeting with European leaders, Ms Truss insisted that Britain had a “good supply” and was in a “much better position than many other countries”.
However, the Prime Minister refused to guarantee that blackouts could be avoided, saying only that Britain would "get through the winter".
She said: “I’m always looking for ways that we can improve the price for consumers.”
EU countries have already agreed to slash gas usage by 10 per cent and electricity by 15 per cent to avert potential continental blackouts this winter. On Thursday, Germany's ambassador to London appeared to suggest Britain should join the push.
Miguel Berger told the BBC: "Half of the French nuclear power plants are not functioning, and that means, and I think the United Kingdom is one of the electricity importers over winter, that there might be some electricity shortages.
"So I think measures like, for example, reducing gas consumption, reducing electricity consumption, are very important signals which need to be given to the population."
Berlin, the Telegraph understands, does not feel it is its role to advise Britain on how to handle a potential energy crisis.
Ms Truss has previously said she would not be telling people to ration their energy use this winter. On Thursday, Downing Street sources ruled out following Brussels' lead, insisting the UK situation was “very different” to that of the EU.
A plan for rolling blackouts, not used since the 1970s, would need the approval of the Government and the King.
Britain may need to import energy from Europe
Ms Truss agreed to rejoin an EU-backed energy pact between the bloc's North Sea countries as she sought to shore up the country's supply ahead of the winter.
She also agreed to draw up plans with Emmanuel Macron for the UK and France to build more nuclear power stations - and urged the EU and Norway to keep supplying Britain with electricity and gas, as they face their own risks of blackouts.
The Prime Minister was urged to launch a public information campaign to warn the public to conserve energy.
Jacob Rees-Mogg, the Business Secretary, signed off plans for a £15m campaign including television and newspaper adverts, with advice on turning off radiators in empty rooms and switching the heating off before heading out.
But Downing Street rejected the proposal, arguing that the information was already readily available, The Times reported.
Professor David Halpern, of the controversial Behavioural Insights Team - known as the “nudge unit” - said households should be warned that heating a room costs eight times more than using an electric blanket and 40 times more than a hot water bottle.
Britain may need to import gas from continental Europe to meet demand in the event of a cold winter, but these supplies could be at risk because of Russia's invasion of Ukraine.
The leaders of Belgium and the Netherlands promised to keep working with Britain to protect Europe's energy security.
"We kept the lights on in London," said Alexander De Croo, the Belgian prime minister, as he called for the construction of more wind infrastructure now that Britain was rejoining the North Seas Energy Cooperation body.
In July, Britain was forced to purchase emergency electricity supplies from Belgium, one of the members of the network.
In Prague, Germany - a member of the group - stopped short of asking Britain to ration energy as a condition for returning to the group.
On Thursday, Downing Street said it was not the Prime Minister's decision on whether there would be blackouts.
Coal-fired power plants due to close in September have also been kept online to produce electricity if needed.
The UK Government has stepped in with support for businesses and households, which is set to cost the state £60 billion over the next six months alone. Wholesale prices are set to remain high this winter.