More than a third of English households will see higher energy bills this winter than they did last winter, according to research published by the Resolution Foundation.
Almost half of those hit by the higher bills will be in the poorest tenth of households, the report said.
Ofgem is expected to announce a reduction in the energy price cap from October, with typical annual energy bills falling from £2,100 last winter to around £1,923 this winter.
This fall is largely driven by falling wholesale gas prices.
Although the price per unit of energy is falling, this will be offset by a rise in the daily standing charge, and the fact that last winter's universal £400 energy support is not being repeated.
As a result, the biggest falls in bills will be seen by households who use the most energy – while households who consume relatively little energy will face higher energy bills this winter.
Jonny Marshall, Senior Economist at the Resolution Foundation, said:
'The cost-of-living squeeze is far from over. And, although government schemes have improved their targeting of support throughout the crisis to those most in need, significant gaps remain which should be urgently addressed to help the most vulnerable get through the challenging months ahead.
'In the longer term, the government needs to reduce the UK's dependency on gas and improve the state of our home insulation to prevent the winter energy crisis from becoming an annual occurrence.'
Internet link: Resolution Foundation website