More than two million UK homes are connected via such smart prepay devices which link up to suppliers and use remote credit payment.
A bitter cold descends on snow-topped terraced houses in north London, as Samantha Pierre-Joseph warms her living room with a small whirring fan heater.
The home, bedecked with snowflake decorations and a Christmas tree, has the central heating switched off to save cash as energy bills rocket but temperatures plunge.
Pierre-Joseph, 40, who lives with her grown-up daughter, was recently switched to a prepayment meter by her supplier following a debt dispute.
She now pays more for electricity and gas than the old direct-debit payment system, worsening the cost-of-living crisis as prices of food and other essentials also soar.
More than two million UK homes are connected via such smart prepay devices which link up to suppliers and use remote credit payment.
Another two million households have older prepay meters which use electronic keys or cards that are charged up at local shops.
“About six weeks ago, I came home from shopping and I went into my kitchen, put bags down and looked at my smart meter,” Pierre-Joseph told AFP.
“And it had a message that said, ‘Top up now’, and had about 3 pounds ($3.60) on there, which was really odd.”
Credit can be purchased online, over the phone or via the post office and a network of small shops.
Domestic energy prices have rocketed across Europe this year following key gas producer Russia’s invasion of Ukraine.
And people with prepayment meters — who tend to be poorer — have been the worst affected because they charge in advance and cost more, according to Peter Smith, policy director at fuel poverty charity National Energy Action.
In contrast, a direct-debit billing system allows consumers to spread the cost and access cheaper tariffs under normal market conditions.
“We know that households on prepayment meters have been the hardest hit by the energy crisis (because) from day one they’ve had to pay for the soaring cost of energy upfront,” Smith told AFP.
“It is a more expensive payment method compared to direct debit.”
Consumer associations estimate that hundreds of thousands of UK homes could be forced into prepayment meters due to spiralling debts during the cold northern hemisphere winter.
Households are rarely disconnected for non-payment of energy bills by suppliers in Britain.