Energy customers with eight suppliers who have a certain type of meter are set to receive payouts of up to £1,000 each after an Ofgem review.

The energy regulator has reviewed actions taken by eight and suppliers who switched vulnerable customers in arrears to paying up front, without their agreement. It means that as many as 40,000 customers who were forced to switch to pre-payment meters - where you have to pay in advance by topping up the meter - could get anything between £40 and £1,000 each paid into their accounts in compensation, as well as having debts written off.

Eligible customers will get between £40 and £500 depending on how they were treated by their supplier, rising to £1,000 for customers who faced 'inappropriate installation' or switch to prepayment meters, Ofgem says. The investigation into Scottish Power, , , , Utility Warehouse, Good Energy, Tru Energy and Ecotricity means customers of those firms are set to receive compensation payments. Octopus Energy inherited cases from Bulb and Shell when it took on their customers.

Those who were given insufficient debt support or unfair treatment will get £250, those who had a vulnerability that was ignored will get £500.

Ofgem's Market Compliance Review (MCR) required suppliers to examine their practices around more than 150,000 cases of involuntary prepayment meter installation, including both meters that were installed under warrant and smart meters that were remotely switched to prepayment mode.

The regulator also examined the warrant process and customer journey when an involuntary PPM is installed, and worked with consumer groups and charities to analyse evidence of the most serious breaches.

Ofgem said the review brings an end to its investigation into eight energy suppliers, but its investigation into British Gas and Utilita is ongoing.

Ofgem's Tim Jarvis, Director General, Markets, said: "This has been one of the most detailed reviews of supplier practices in Ofgem's history looking at tens of thousands of cases. It has taken time, but our priority has been to put things right for those who weren't treated properly, and ensure we don't see bad practice repeated.

"While the number of cases where a prepayment meter was wrongfully installed is relatively low compared to the total number of PPM customers, one case is one too many.

"Our review also found wider issues with the processes suppliers had in place, which is why we've put in place clearer, tougher rules to protect customers in vulnerable situations, and I'm pleased that from today suppliers will be applying our compensation framework for those customers affected and have also committed to further support such as debt write off."

Les Roberts, Content Manager at business energy firm Bionic has provided some guidance on your rights as a consumer.

He said: "Energy companies are set to pay out around £70m to customers who faced "inappropriate installation" of a prepayment meter after they fell behind on energy bills. "Ofgem have said that customers don't need to do anything to receive their pay-out as it'll be paid directly into their customer account.

"When it comes to prepayment installation your energy provider does have the right to take action if you stop paying your direct debit and begin to rack up debt. They could potentially move you on to a prepayment meter, which means you would most likely be paying a higher rate. A prepayment meter requires you to pay for energy as you use it.

"However, you do have some rights as a consumer before this happens. Your supplier has to give you at least 28 days to repay your debt before they take action. They cannot enter your home and install a prepayment meter without at least 7 days prior warning. You can also refuse a prepayment meter if you are unable to physically reach your meter or top up the balance at a shop. For example, if you are disabled, ill or live very remotely.

"If all the above conditions are met and you still refuse to pay, your supplier does have the right to gain a warrant to enter your home and install the meter or they could change your smart meter setting to a pay-as-you-go set up."