The figure is set to rise by another 2.5 million in October, when the energy price cap is expected to rise again, according to the Resolution Foundation.

Average energy bills for those on a standard variable tariff, which are protected by the price cap, has soared from £1,277 to £1,971 today. For those on a prepayment meter, prices have risen more steeply, from £1,309 to £2,017 – an increase of £708.

In an attempt to manage energy costs, millions tried to submit meter readings yesterday, before price hikes kicked in, causing many energy providers’ websites to crash.

This bill hike is just one of many coming into force including petrol, food, and council tax costs along with national insurance. It comes as inflation is soaring and there is little relief in sight for households.

Low-income earners are set to be hit hardest with energy bills and a fifth of the poorest households are now spending 10% of their budgets on energy costs, compared to 4% for the richest fifth.

Those in households with poor insulation and an energy efficiency rating of E are also set to see their prices rise by around £320 more than those in houses with an energy efficiency rating of C. This could rise to a difference of £380 by the autumn.

Prices are set to get higher in the autumn too. If Ofgem’s price cap increases by £500 in October, which is less than the £830 predicted by the Office for Budget Responsibility (OBR), this could push 7.5 million households (32%) into fuel stress.

‘Rebate schemes don’t go far enough’

The government has announced some help to cope with rising bills. Its energy rebate scheme will give a £200 discount on energy bills. This will be automatically applied in October and repaid in £40 instalments over the next five years.

It is also giving a £150 council tax rebate to those in council tax bands A-D to help with costs. This will be applied to your council tax account automatically if you are eligible.

Yet this does not go far enough to protect low-income households, according to the leading think tank, calling the scheme ‘deeply flawed’.

It said offering council tax rebates is not the most effective way of helping people, given that 11% of the poorest households are ineligible for the rebate as they live in properties in bands E-H, while 59% of the richest households are eligible.

It also doesn’t guarantee the money will help with energy bills, such as if landlords pay council tax bills and don’t pass this saving on.

Support through the benefits system would be more valuable in helping poorer households, and the Foundations said the government also needs to address how it supplies and prices energy, to avoid future fossil-fuel price shocks.

Jonathan Marshall, senior economist at the Resolution Foundation, said: “Today’s energy price cap rise will see the number of households experiencing fuel stress double to five million.

“The price cap is expected to rise sharply again on 1 October, when a further 2.5 million households could fall into fuel stress this autumn, unless more support is provided.

“There are no easy ways to protect people from rising bills in the current climate. But with many of the poorest households missing out on the council tax rebate, this scheme should be used to supplement, rather than replace, support via the benefit system, which is better equipped to target lower-income families.”