We've updated our methodology to calculate matching scores for renewable tariffs. So Energy is the first supplier to partner with Matched to validate their scores under this revision.
Previously, Matched just calculated whole-portfolio matching scores. These show how much renewable power a supplier delivers across all customers, regardless of tariff. But many suppliers offer both renewable and non-renewable tariffs. A supplier might achieve 50% matching overall while their renewable tariff customers get 80% and their standard tariff customers get 30%.
Consumer choice matters. You pick your supplier and you pick your tariff. Our v1.3 methodology now reflects that.
How it works
The calculation differs from portfolio scores in one step: rather than looking at the demand of the entire portfolio, we drill into the demand of customers on renewable tariffs.
Suppliers with renewable tariffs commit to 100% annual matching for those products. You consume 3 MWh over the year on a renewable tariff. Your supplier procures at least 3 MWh of renewable certificates.
But renewable tariff customers are only a portion of the supplier's total base. If a supplier has 1,000 GWh of total demand but procures 800 GWh of renewable supply, renewable tariff customers consume at most 800 GWh. With the suppliers's validation, we scale total demand down to match renewable supply before calculating temporal alignment.
From there, the rest of the calculation is unchanged.
Key assumptions
The methodology requires two assumptions, which we validate with suppliers before publishing:
First, renewable tariffs deliver 100% annual volumetric matching - REGO volumes allocated to the tariff equal consumption.
Second, demand profiles are similar across tariffs. Renewable tariff customers use electricity in the same pattern as non-renewable customers. Without tariff-level metering data, we assume demand generally follows the same daily and seasonal rhythms regardless of tariff choice. This holds for most customers. Your heating switches on at 6pm whether you've chosen a renewable tariff or not. Consumption predominantly depends upon occupancy, business hours and weather, not tariff selection.
So Energy delivers 74% renewable on an hourly basis
So Energy achieves 50% matching across their whole portfolio, when measured hour-by-hour. But they offer both renewable and non-renewable tariffs. What do renewable tariff customers actually get?
We worked with So Energy to validate the methodology. Their website publicly declares that their renewable tariffs deliver 100% annual matching. They confirmed their customers' consumption patterns don't materially vary by tariff. With those foundations established, we calculated their renewable tariff score.
So Energy serves 1.2 TWh of total demand. They procure 0.7 TWh of renewable supply. For the renewable tariff calculation, we scale consumption to match renewable supply. The scaling factor is 0.7 / 1.2 = 0.58.
We then measure temporal alignment. During some half-hours, So Energy's wind and solar generators produce more than enough to cover scaled consumption. During others, particularly in February and March, generation falls short.
So Energy's renewable tariff customers get 74% clean power - a high score. The 24 percentage point improvement from portfolio to renewable tariff demonstrates the value of dual measurement: renewable tariff customers are getting meaningfully cleaner power.
Who this matters for
Renewable tariff scores apply to suppliers offering distinct renewable and non-renewable products. Suppliers with mixed portfolios can now show customers what their renewable tariffs actually deliver.
The methodology doesn't apply to suppliers like Good Energy or Bryt Energy whose entire portfolios are renewable. They don't offer non-renewable tariffs. Their portfolio score already represents what every customer receives.
Why consumer choice matters
You choose your supplier based on their matching performance. You choose whether to pay extra for a renewable tariff. Both decisions matter.
The portfolio score tells you how the supplier performs across all customers. The renewable tariff score tells you what you're getting if you select their renewable product. Some suppliers achieve high renewable tariff matching through careful procurement practices. Others offer renewable tariffs that deliver the same mix as their standard products, just with certificates attached.
You can now see the difference.
Consumer choice drives market evolution. Suppliers who achieve high renewable tariff matching can differentiate on quality. Consumers who want genuinely clean electricity can identify the tariffs that deliver it.
What's next
So Energy is the first supplier to validate their renewable tariff data with us. We're working with others to extend coverage.
The full methodology update is published on our methodology page. We've added detailed sections on renewable tariff calculations.
We'll announce the complete updated index in the coming weeks, including renewable tariff scores for all suppliers who've validated their commitments with us. The index will show both portfolio and renewable tariff performance.
If you're a supplier offering renewable tariffs, we invite you to follow So Energy's lead, and work with us to validate your data and publish your scores.