Many British consumers pay for 100% renewable electricity. But how much are they actually getting?

The power sector has a dedicated system to track the generation and consumption of renewable power, and suppliers use it to back their green energy claims. But there’s a problem. The rules allow suppliers to claim that summer power from solar farms is being used to cover winter evening power that came from gas plants. Your heating at 6pm in January? Almost certainly powered by fossil fuels, no matter what your tariff says.

This isn’t fraud. Suppliers are following rules set over 20 years ago, back in 2003, when renewables generated less than 3% of Britain’s electricity. But renewables now regularly provide more than half our power, varying between 5% and 80% depending on weather and season. The old system hasn’t kept pace.

We’ve set out to fix this, with the newly published Matched Clean Power Index.

Calculating hourly matching scores

The data to calculate what types of energy consumers actually get already exists. The National Energy System Operator tracks renewable generation, Ofgem tracks who buys it, Elexon records supply and demand. We’ve combined these public sources to show how well renewable supply aligns with customer demand, hour by hour.

Here’s what that reveals. When a solar farm generates power on a summer afternoon, that electricity flows to whoever’s consuming at that moment—likely customers of multiple suppliers across the grid. But that solar power can be claimed by a single supplier, and used to offset the gas-generated electricity they serve their customers on winter evenings. The system currently trades in paper claims, not physical delivery.

The results reveal stark differences. Good Energy is 88% renewable. Octopus manages 69% across a huge portfolio that is nearly 30 TWh. Check what you’re getting – we see electricity branded as 100% renewable that is actually only 55%.

We developed the methodology with over 30 energy sector experts, including those at Imperial College London, Oxford University, and Princeton. We worked with suppliers including npower, Good Energy, and So Energy. We’ve benefited greatly from collaborations with leading hourly matching organisations like Granular Energy and EnergyTag, and with others across the sector who are eager to see the system improved. The full methodology is published at matched.energy/methodology. Anyone can verify our calculations.

Visit the Index to see how your supplier performs.

Why this matters

Consumers can make better choices. Leading suppliers can demonstrate what they’re already doing well. And we all get clearer sight of where the system needs to improve.

Britain is aiming for Clean Power by 2030. Getting there affordably means reducing our reliance on gas. We can do this by directing investment to renewable generation, storage, and flexibility that actually matches when we use electricity, particularly those hard-to-reach hours. Not just claiming cheap summer renewables to cover expensive winter gas.

The Matched Clean Power Index shows that it’s possible to align renewable generation with consumption – several suppliers are already doing it.

What’s next for Matched?

Our work is only just beginning. Our priorities are:

1. Making the data available to companies and individuals that can use it. We’re already working with carbon accountants, academics, consultancies, consumers, and suppliers.
2. Expanding the Index to include nuclear generation alongside renewables for a complete picture of low-carbon matching.
3. Engaging with policy makers on how temporal matching can help deliver Clean Power 2030 more affordably.

If you have any feedback or want to talk about using Matched’s data, please get in touch.