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How the scores are worked out

This advice applies to Wales

We compare energy suppliers' customer service by looking at data from a number of reliable sources. We publish data about suppliers with more than 25,000 customer accounts.

Data about complaints to third parties

We base our ratings on complaints made to:

  • the Citizens Advice Consumer Service

  • the Extra Help Unit

  • the Energy Ombudsman

Data about customer service, billing and switching

We use data from suppliers to work out:

  • their average call centre wait time - except time spent in sales lines
  • the number of emails they answered within 2 working days
  • their average response time for messages on social media - where they’re contacted more than 5% of the time through social media
  • the number of their customers who got a bill based on a meter reading in the past year - except prepayment customers
  • the number of switches completed within 15 working days of agreeing the contract

Data about customer guarantees

We base our ratings on suppliers’ membership of the Energy Switch Guarantee and the Vulnerability Commitment.

If a supplier is a member of the Energy Switch Guarantee, they have to meet certain criteria - such as completing 98% of switches within 21 days. Find out more about the Energy Switch scheme on the Energy Switch Guarantee website.

If a supplier is a member of the Vulnerability Commitment, they have to promise to improve their support to vulnerable customers, who might be facing financial difficulties or illnesses. Find out more about the Vulnerability Commitment on the Energy UK website.

Suppliers score 3 points for membership of the Energy Switch Guarantee or the Vulnerability Commitment. If they're a member of both, their score is capped at 5 points. Trial members of the Energy Switch Guarantee score 2 points.

If we don't have data for your supplier

Suppliers are legally required to share the data we use in this rating. They also need to have a referral system to our consumer service.

If they don’t, we score them zero in categories related to these things.

We need suppliers to give us permission to publish data they share with us. If they don’t, you’ll only see a star rating.

How we come up with a star rating

We give energy suppliers a score out of 5 for each category. 5 is excellent and 1 is poor. Then we give them an overall star rating out of 5.

Category54321
Number of complaints per 10,000 customers 5 or less 5 to 15 15 to 30 30 to 55 More than 55
Average call centre wait time (seconds) Less than 30s 30s - 90s 90s - 180s 180s - 300s More than 300s
Emails responded to within 2 working days More than 95% 95 - 80% 80 - 60% 60 - 40% Less than 40%
Average social media response time Less than 30 mins 30 - 60 mins 1 - 2 hours 2 - 4 hours More than 4 hours
Switches completed within 15 working days More than 98% 95 - 98% 90 - 95% 80 - 90% Less than 80%
Customers who had accurate bill in the past year
Customer guarantees

Suppliers score 3 points each for membership of the Energy Switch Guarantee and membership of the Vulnerability Commitment (up to a maximum of 5 points). Trial members of the Energy Switch Guarantee score 2 points.

Not all categories are equal. Some, like complaints, count more towards the final score than others.

This is how we work out the overall scores.

CategoryMeasured asCounts towards overall score
Complaints to third parties Complaints to third parties 35%
Billing Bill accuracy 20%
Customer service Average call centre wait time 15%
Email response time 10% or 5% if they’re also scored on social media response time
Social media response time - if contacted more than 5% of the time through social media 5%
Switching Switches completed within 15 working days 10%
Customer guarantees Membership of a range of schemes 10%


To measure bill accuracy, suppliers must have been supplying more than 5,000 customer accounts for 12 months. 

Some suppliers have mostly customers who pay by prepayment. Suppliers with fewer than 5,000 billed customers do not receive a billing score, and are scored on the other categories only.

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