Recent research by Citizens Advice found that, while price was the biggest factor when thinking about switching, having extra information on what the supplier is like to deal with could also help customers make a final choice.

The tool uses a star rating system from 1 to 5, with the number of stars awarded to each supplier based on a combination of different factors:

• Complaints –  how well energy suppliers handle customer complaints

• Ease of switching – the number of switches the supplier successfully carries out within 21 days

• Ease of contact  - how highly people rate their supplier’s customer service

• Bill clarity – how easy people find it to understand their bills

• Switch Guarantee – whether the supplier is signed up to the switch guarantee that commits them to switching a customer within 21 days

The criteria were developed from research carried out with customers who were asked what they valued most from their energy supplier. The tool will be updated quarterly with the latest information and star rating.

The star rating for each energy supplier will also appear as part of Citizens Advice’s price comparison tool. This means people will be able to see costs alongside the customer service rating to work out the best deal for them.

GIllian Guy, Chief Executive of Citizens Advice, said: “While people said that price was their primary consideration when switching energy supplier, customer service also has some bearing on their decision. The new star rating will make it easier for people to tell how good a supplier is at customer service so they can make sure they find the company that best suits their needs: on price and service.

“We also hope the tool will encourage suppliers to improve their level of customer service with customers now able to scrutinise their performance across a range of different service factors – from complaints to ease of switching.”

The ratings for October to December 2016 were: