Which? Eco Provider energy companies revealed for 2022

Energy has rarely been such a hot topic. The focus remains firmly on the high prices of electricity and gas, but our research has found that making sure energy is as green as possible is still important to UK customers.

In a Which? survey carried out in August 2022, 55% told us that an energy provider’s sustainability credentials are important when choosing a supplier. The same percentage said that building more renewable generation capacity, such as wind turbines and solar farms, would make them more likely to choose an energy company.

Energy companies approach 'green energy' very differently, and it can be confusing to figure out what impact your own tariff has. We've assessed energy companies on their sustainability to see how they compare, so that you can find out how your provider ranks.

Three energy providers – Ecotricity, GEUK and Good Energy – stood out above the rest to be named our Eco Providers for 2022. Bulb and Octopus got the next- most points, along with London Power and M&S Energy, which are supplied by Octopus.

Find out more about green energy suppliers or head to Which?'s latest sustainability news. 

Which? Eco Providers: Ecotricity, GEUK and Good Energy 

We've analysed energy companies on a range of sustainability criteria. Some of this was available to us via their websites, but we had to request some of the data from the energy companies themselves.

Ecotricity, GEUK and Good Energy tied for first place, and all three get our Eco Provider recommendation. All three got top marks for selling only 100% renewable electricity. 

• Ecotricity generates around a third of its electricity itself. It buys another third directly from generators under Power Purchase Agreements (PPAs), and matches the remaining third with Renewable Energy Guarantees of Origin (REGOs). It continues to build new green generation capacity, which it says is the most important thing. It is also the only vegan-certified energy supplier.
• GEUK and Good Energy don’t generate energy themselves, but they only buy 100% renewable electricity through PPA contracts to supply their customers. Good Energy says it is the only energy company in the UK with more generator customers than supply customers, as it buys clean electricity from more than 180,000 small scale generators, while GEUK is the only supplier of 100% green gas, sourced only from waste.

The table below details the results of our findings at every energy company that responded to our data request. Swipe or scroll right to see the total score breakdown in full. 

*Partnered or supplied by Octopus Energy  **Part of OVO 

How we scored supplier sustainability

We requested information from suppliers in August 2022. Two companies - E Energy and E.On Next (which also supplies Sainsbury's Energy customers) - did not respond, so we excluded them from the table above.

Points were awarded based on the companies' responses, and on information published on their websites, including the annual Fuel Mix Disclosure (FMD).

• Sale of renewable energy: We awarded a point for supplying a greater percentage of renewable energy than the fuel mix average, and an additional point for supplying 100% renewable energy.
• Generating or buying renewables direct: Suppliers were awarded points for generating renewable energy, and additional points according to the percentage of customer supply that this accounted for; and for buying renewable energy direct from generators through PPAs or similar contract arrangements, and additional points according to the percentage of customer supply that this accounted for.
• Matching customers' power with renewable generation: Suppliers received points if all energy supplied to customers was matched by their own renewable generation and/or direct purchasing contracts. A point was awarded if 100% of supply was covered by REGO certificates, but a point was deducted for power backed by GoO certificates (which support non-UK produced power).
• Selling carbon-intense power: We deducted a point for suppliers that sold carbon-intense power generated from fossil fuels (as reported in the annual FMD).
• Selling green gas: We awarded a point for selling green gas, and a further point if this made up more than 5% of gas sold.
• Offering time-of-use tariffs: Suppliers that offer one or more ToU tariffs received a point. That's because time of use tariffs encourage customers to use energy at low-demand times, which is when the National Grid has the most renewable energy in its mix. 
• Offering above-average Smart Export Guarantee rates: We awarded one point to suppliers that offer a higher than average export rate to domestic generators such as those with solar panels (average calculated from responses received).
• Transparency and clarity: We checked suppliers' websites and awarded points for clarity and accessibility of information about their renewable energy offer. 

We gave the highest marks to companies that supply 100% renewable energy to all their customers, generate renewable energy themselves and/or contract directly with companies that do. We also awarded points to suppliers that back all their renewable energy supply with REGOs, which come from renewable energy generated in the UK. 

Suppliers also got points for supplying green gas (not including offsetting), for offering time-of-use tariffs (which can help customers save money as well as reducing energy demand at peak times), and for paying a higher-than-average Smart Export Guarantee (SEG) rate, for customers who generate and sell renewable energy back to the grid.

Learn more about sources of renewable energy in the UK, and how tariffs are sold as renewable.

Transparency is key

More than half our customer survey respondents (53%) said it was important to them that energy companies are transparent about where their renewable electricity comes from. We analysed data given to us by the suppliers, but we were unable to include those that did not respond to our data request - E Energy and E.On Next.

We also looked at each supplier’s website to see if they were clear to their customer about how sustainable their energy supplies are and where their renewable energy comes from. Where clear information was available on the homepage or within one click, companies received full marks for transparency. Making it easy for customers to access this information is a crucial step for energy companies.

Should you choose a renewable energy tariff?

Our top three sustainable energy suppliers are no surprise - they were also named our first Eco Providers for energy last year. 

However, they are also the only three suppliers that have a permanent exemption from Ofgem’s energy price cap because of how much they invest in the growth of renewable energy. This means they can charge customers a higher rate than the price cap, so they may not be a feasible choice for many people right now.

But that doesn’t mean that renewable energy is not an option. Other suppliers in our table scored highly for selling, generating, or buying renewable electricity. Some suppliers may not have scored well overall but do offer green tariffs that would score highly if considered individually.  

If you’re looking for a time-of-use tariff that rewards you for charging your EV at night, for example, or an export tariff that pays well for excess power from your solar panels, it’s worth shopping around. The more you're rewarded for using energy at off-peak times, the better, as that's when the National Grid's energy supply is most renewable.

Read our energy company reviews to find out more about individual suppliers.

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