Some 10 million households are being urged to send an energy meter reading to their supplier as the cheaper prices come into effect.
Gas and electricity bills are set to drop by around £122 from July 1.
Ofgem's energy price cap has dropped by seven per cent from the previous £1,690 for a typical dual fuel household in England, Scotland and Wales to £1,568. This is a fall of £122 over the course of a year, and around £500 less than the cap in July last year, when it was £2,074.
However, national Debtline said its findings suggested 6.1 million people were struggling to pay their energy bills, despite dropping prices.
Energy debt figures now stand at a record £3.1billion, according to latest Ofgem figures.
While the lower price cap would bring some relief, the service called for “urgent action” to help those facing unaffordable arrears.
The energy price cap controls what most households in England, Scotland and Wales pay for energyGETTYHouseholds on a standard variable tariff are being urged to submit their electricity and gas readings to their supplier as close as possible to July 1 to ensure they are billed accurately at the lower prices.
Those who do not submit readings risk having some of their usage after this date charged at the previous, more expensive rates.
Suppliers who have not received meter readings base their bills on estimated usage, meaning households could be overpaying, while others may not be paying enough.
Steve Vaid, chief executive of the Money Advice Trust, the charity that runs National Debtline, said: “The fall in the price cap will alleviate some of the pressure many households are under, but our findings show that many more will continue to struggle as energy bills remain high.
“As millions of people worry about keeping up with their energy payments, arrears levels have continued to increase and many have been left with unaffordable debts as a result.
“What we need to see from the next Government is urgent action through a Help to Repay scheme to help people trapped in energy debt access a safe route out.
“Anyone struggling with their energy bills, or worried about their finances, should contact National Debtline as soon as possible – our advisers are here to help.”
The average household is expected to spend £83 on energy in July, compared with £127 in June, due to the lower cap and lower usage due to warmer weather, comparison site Uswitch calculated.
The latest fall offers further relief to households given the previous quarter-on-quarter drop seen in April, but analysts have said they expect Ofgem to increase the price cap in October, before dropping it again in January 2025.
Uswitch also urged households to investigate other tariffs, including fixed deals, to beat the predicted October price hikes.
Those who opt for a fixed deal instead of a standard variable tarrif will not need to worry about changes to the price cap as their monthly payments will be fixed for the term they have.
Ben Gallizzi, energy spokesman at Uswitch, said: “There are a number of fixed tariffs worth considering right now.
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By opting for a fixed deal, you’re locking in those rates for the duration – usually 12 months – which means households could have price certainty and avoid the ups and downs of the price cap.”
To work out if an energy deal - fixed or otherwise - is cheaper than what someone is paying now, they can compare the unit rate and standing charge with what they currently pay.
The average home is paying rates limited by the Ofgem price cap.
From July 1, that means paying 60.12p a day in electricity standing charges and 31.41p for gas, while electricity unit rates will be 22.36p per kilowatt-hour (kWh) and 5.48p/kWh for gas.
