Which? Eco Provider energy companies revealed for 2023
Four energy companies have made the grade to become Which? Eco Providers for energy in 2023: 100Green, Ecotricity, Good Energy and Octopus Energy.
Three of them have previously held the title. Octopus Energy is an Eco Provider for the first time this year.
Energy companies approach 'green energy' and sustainability very differently. Some have been supporting and generating renewable power for many years, some are helping customers cut their home's carbon footprint in more ways, and some are still doing surprisingly little towards decarbonising our energy grid. That makes it tricky to work out what impact your own energy tariff has.
So we've assessed energy companies on a range of sustainability criteria to see how they compare - and so you can find out how your provider stacks up.
With very little to choose from in terms of energy prices at the moment, it could be a good time to choose a provider with strong green credentials.
Find out more about the differences between green energy suppliers.
Which? Eco Providers for 2023: 100 Green, Ecotricity, Good Energy and Octopus Energy
We assessed 17 energy firms on a range of sustainability criteria. We asked energy companies to answer a series of questions as well as looking for information on their websites.
Our Eco Providers all got close to full marks for buying and selling renewable power and score highly for generating renewable power or selling green gas.
- Good Energy buys enough power for all of its customers directly from renewable generators, around 40% of which don’t get government subsidies. That’s important because it means it’s supporting generators that might not otherwise exist. 10% of its gas is green.
- Octopus Energy generates renewable power, with three wind turbines in the UK, through its company Octopus Renewables. It buys around 10% of its renewable power directly from generators. It has a wide choice of flexible tariffs to encourage off-peak energy use and offers domestic heat pump installations.
- 100Green buys all of its renewable power directly from generators, some of which don’t get government subsidies. It’s the only firm selling 100% green gas, sourced only from waste.
- Ecotricity generates electricity from onshore wind and solar, plus more than a fifth comes from both subsidised and unsubsidised generators. It invests profits into building more green energy generation, like its green gas mill.
The table below shows how each company scored. Suppliers are included whether or not they make green claims to give you the full picture of the energy market. Companies which did not provide the information we requested could not be awarded points for it.
Swipe or scroll right to see the total score breakdown in full.
| Overall score (%) | Total score (max 20) | Generating renewable power (max 4) | Buying and selling renewable power (max 7) | Generates or buys directly carbon intense power (max 0) | Sells green gas (max 2) | TOU and SEG tariffs (max 2) | Low carbon installations (max 2) | Transparency and clarity (max 3) | |
| Good Energy (Eco Provider) | 80% | 16 | 0 | 7 | 0 | 2 | 2 | 2 | 3 |
| Octopus Energy* (Eco Provider) | 80% | 16 | 3 | 6 | 0 | 0 | 2 | 2 | 3 |
| 100Green (Eco Provider) | 70% | 14 | 0 | 7 | 0 | 2 | 2 | 0 | 3 |
| Ecotricity (Eco Provider) | 70% | 14 | 3 | 6 | 0 | 1 | 0 | 1 | 3 |
| British Gas** | 70% | 14 | 2 | 4 | 0 | 1 | 2 | 2 | 3 |
| Co-op Energy | 65% | 13 | 2 | 6 | 0 | 0 | 0 | 2 | 3 |
| Ovo Energy | 60% | 12 | 0 | 5 | 0 | 1 | 1 | 2 | 3 |
*Octopus Energy supplies Affect Energy, Ebico Living and London Power customers. Ebico Living and London Power customers cannot access Octopus's Time of Use (TOU) or Smart Export Guarantee (SEG) tariffs. Octopus Energy is also buying Shell Energy's business.
**British Gas is not an Eco Provider because its parent company, Centrica, has a direct relationship with fossil fuels.
***E.ON Next initially told us it did not generate renewable electricity. However after Which? shared its press release it said that it actually owns two biomass CHPs (one in Lockerbie and one in Sheffield) as well as a geothermal energy centre in the city of London. E.ON Next supplies Sainsbury's Energy customers.
How we scored energy suppliers on sustainability
We requested information from 17 energy firms in August 2023, as much of the information required for our assessment was not publicly available. Points were awarded based on the responses companies gave to our questions and on information publically available on their websites, such as their annual Fuel Mix Disclosure (FMD).
- Generating renewable power: Points were awarded to those that generate renewable electricity. They got more points where it accounted for a greater proportion of their customers' use.
- Buying and selling renewable power: Companies were awarded points for buying renewable power directly from generators through PPAs or similar contract arrangements. Additional points are given according to the percentage of customer supply this accounts for and whether it comes from generators that don't already receive government subsidies. Companies also gained points in this category for supplying a greater percentage of renewable energy than the fuel mix average, and another point for supplying 100% renewable electricity. A point was deducted for power backed by GoO certifications (which support non-UK produced renewable power).
- Carbon intense power: Points were deducted for generating electricity from fossil fuels or buying directly from fossil-fuel generators.
- Green gas: We gave a point for selling green gas, and another one if it it made up more than 5% of gas sold.
- Time of use (TOU) and Smart Export Guarantee (SEG) tariffs: Firms recieved a point if they offer one or more ToU tariffs. These encourage customers to use energy at less popular times, which is when the National Grid has most renewable energy in its mix. We awarded a point to suppliers that have above average SEG rates for domestic generators, such as homes with solar panels installed. We calculated this based on responses received.
- Low carbon installations: Suppliers earned points for providing customers with ways to reduce their carbon footprint by installing heat pumps, solar panels, battery storage and insulation.
- Transparency and clarity: Points were awarded for websites with clear, easy-to-find information about how renewable electricity is sourced. Also for sharing with Which? a breakdown of their greenhouse gas emissions data.
Find out more about sources of renewable energy in the UK and whether you could install any at home.
Should you switch to a renewable energy tariff?
Three of our energy Eco Providers - 100Green, Ecotricity and Good Energy - are also the only three suppliers that are exempt from Ofgem's energy price cap. This is because of how much they invest in the growth of renewable energy. It means they can charge customers more than the price cap. That means you might find their rates are a little higher than you'd pay elsewhere. But if you're committed to investing in green energy generation, it's worth looking into how they operate.
Read more: the energy price cap explained
Our fourth Eco Provider, Octopus Energy, has a variable tariff that is subject to the price cap. That means your rates are likely to be similar to those you'd pay elsewhere.
There are other suppliers in our table that aren't Eco Providers but do score highly for generating or buying and selling renewable electricity.
If you're able to make use of off-peak energy, particularly for charging an electric car or operating a heat pump, it's also worth comparing suppliers' rates and set ups for their specialist time of use tariffs, which may be able to save you money on your bils.
And if you have solar panels that generate extra electricity that you sell back to the grid, it's well worth making sure you compare the available rates for SEG tariffs.
Find out more about the differences between green energy suppliers or read our energy company reviews to find out about each energy supplier.
