Half a million pre-payment energy meters have been forcibly installed in people’s homes over the last six years, according to figures obtained by BBC Radio 5 live.
The energy watchdog Ofgem has said it will investigate the practice saying it should only be used as a last resort.
Energy suppliers can gain a court order to install a pre-pay meter when customers run up debt reports BBC.
Industry body Energy UK said pre-paying helped some people manage a budget.
But Citizens Advice said pre-pay customers got a “raw deal”, paying £80 a year more on average than direct debit customers.
The figures, supplied by Ofgem in response to a Freedom of Information request. showed about 97,000 pre-pay gas and electricity meters were installed in England, Wales and Scotland last year alone.
In 2009, the first year figures were made available for, there were 36,837 electricity pre-payment meters and 26,711 gas meters installed – a combined total of just over 63,000.
In 2014, the figure had risen to 49,615 for electricity and 47,876 gas – totalling about 97,000.
The numbers were highest in 2013, when a combined total of about 111,000 pre-payment meters (PPMs) were installed.