Energy customers in Wales can expect payouts of up to £1,000 each, with debts possibly written off due to the forced fitting of prepayment meters.
Energy companies are compensating customers with over £70m in total.
Eligible customers may receive payments starting at £40, with the possibility of reaching up to £1,000 for inappropriate installation.
Ofgem intervened after energy firms switched vulnerable customers without their consent during the cost of living crisis.