Executive summary
The 2026 Supplier Performance Report ranks the UK's major domestic energy suppliers on the measures that matter to households: value, billing accuracy, customer service, complaint resolution and overall reliability. Every score is derived from published complaints data, independent service metrics and PowerGuardian's own tariff monitoring — with no commission or supplier funding influencing the results.
This year the gap between the best and worst performers widened. A small group of suppliers combined competitive fixed tariffs with strong service, while several large incumbents continued to lag on complaint handling despite price stability across the market.
Key findings
- The top three suppliers resolved over 90% of complaints within eight weeks, more than double the rate of the bottom quartile.
- Billing accuracy remains the single biggest driver of customer dissatisfaction, ahead of price.
- Fixed tariffs from mid-size suppliers frequently beat the price cap by £80–£160 a year for typical usage.
- Smaller, specialist suppliers scored highest on service but offered a narrower range of tariffs.
How suppliers were scored
Each supplier is scored across five weighted pillars: value (30%), billing accuracy (25%), customer service (20%), complaint resolution (15%) and reliability (10%). Scores are normalised to a 0–100 scale so suppliers of different sizes can be compared fairly.
We deliberately weight value and billing accuracy most heavily because these are the areas where households feel the impact of a poor supplier most directly — through higher costs or incorrect charges.
What separates the best from the rest
The strongest performers share three traits: transparent tariffs without hidden exit penalties, accurate and timely billing, and fast complaint resolution. Where a supplier scored poorly, it was almost always because of slow or unresolved complaints rather than headline price.
For most households, switching from a bottom-quartile supplier to a top-quartile one improves both cost and experience — the two are not a trade-off.
Data & charts
Explore the key figures behind this report. Charts and tables are interactive — hover, sort and compare.
Overall supplier performance score
Weighted 0–100 score across value, billing, service, complaints and reliability.
- Overall score
Source: PowerGuardian 2026 Supplier Performance Report
Score breakdown by pillar
How the top suppliers score on each weighted pillar. Sort by any column.
| Supplier A | 90 | 88 | 86 | 92 | 88 |
| Supplier B | 86 | 84 | 82 | 85 | 84 |
| Supplier C | 82 | 80 | 84 | 79 | 81 |
| Supplier D | 74 | 68 | 76 | 70 | 72 |
Source: PowerGuardian 2026 Supplier Performance Report
Download the full PDF report
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Methodology
- Complaints and service metrics are sourced from Ofgem and Citizens Advice supplier performance data.
- Tariff value is measured against Ofgem Typical Domestic Consumption Values and the prevailing price cap.
- Each pillar is normalised and combined using the fixed weights described above; no supplier can pay to change its score.
Sources & references
- Ofgem — Energy price cap — UK regulator's quarterly price cap announcements
- Citizens Advice — Energy supplier comparison — Independent supplier guidance & complaints data
- Ofgem — Typical Domestic Consumption Values — Standard usage assumptions for UK households
Figures are checked against primary sources before publication. See our methodology for details.
