You're paying for 100% renewable electricity. Your supplier claims 100% renewable on their tariff. But hour by hour, what renewable generation have they actually bought?
Matched uses public data to provide the answer.
We know from Ofgem's public renewable energy certificates (REGOs) registry which renewable generators each supplier has bought from. Combine these monthly certificates with actual generation metering data from those plants, and you can see exactly what renewable power each supplier has procured, every half hour of the year.
This matters for more than consumer transparency. Corporations reporting their carbon footprints need to know whether their renewable electricity claims reflect physical reality or just annual accounting. A data centre running at peak load during winter evenings that claims carbon neutrality from summer solar certificates has a problem. The power they actually consume comes from gas plants.
How we track renewable generation by supplier
The UK publishes REGO retirement data monthly. Each certificate ties to a specific generator. Cross-reference those generators with Elexon settlement data, and you get half-hourly generation output for every wind farm, solar array, and hydro plant that each supplier has bought from. For the subset of volume not covered by Elexon, we use grid mix data to accurately infer the half-hourly shape of generation. The UK's public data infrastructure makes this level of scrutiny possible—most countries don't publish data at this granularity.
Why supplier portfolios matter
Good Energy's generation portfolio looks completely different from British Gas. One supplier might lean heavily on offshore wind. Another might buy predominantly solar. A third might source from onshore wind and biomass.
These choices determine when suppliers can actually deliver clean power. Solar generates during the day. Wind generates whenever it's windy, often at night in winter. A supplier's portfolio might generate 80% of annual consumption, but that tells you nothing about January evenings when demand peaks and solar contributes nothing.
Look at a typical winter day. Solar generation climbs from 7am, peaks around noon, drops to zero by 4pm. Wind might be strong overnight, calm during the day, or vice versa. Consumer demand peaks between 5pm and 7pm, precisely when solar has disappeared and the grid relies on gas.
Summer looks completely different. Long daylight hours mean abundant solar. Demand is lower, especially in the evening. Wind tends to be calmer. A supplier heavy on solar certificates might achieve 95% matching in July and 45% in January.
Track this hourly, and patterns emerge. Some suppliers maintain consistent generation across all hours. Others spike during summer days and disappear during winter evenings. The variation matters far more than the annual average.
The carbon accounting problem
Corporate carbon accounting for electricity has historically used two approaches, both flawed.
Location-based accounting uses the average grid carbon intensity. If the UK grid is 45% renewable, your reported emissions reflect that mix regardless of which supplier you buy from. This ignores procurement entirely. Buying from the greenest supplier or the dirtiest makes no difference to your reported emissions.
Annual market-based accounting uses renewable certificates to adjust your reported emissions. Buy enough annual renewable certificates to cover your consumption, and you can report zero emissions. The problem: this ignores when the renewable energy was generated. A data centre running at peak load during winter evenings can claim carbon neutrality by buying summer solar certificates. The physical power came from gas plants, but the accounts show zero emissions.
Neither approach reflects the physical reality of what power you're actually using hour by hour.
The GHG Protocol and Science Based Targets initiative are now revising their standards, with renewable electricity accounting emerging as one of the most pressing issues. The revision could reshape how every major corporation reports electricity emissions.
Why hourly matching solves this
Hourly market-based matching at the supplier level solves both problems. It accounts for procurement decisions while reflecting temporal reality. Companies paying premium green tariffs can verify their actual carbon footprint based on their supplier's hour-by-hour renewable generation. If your supplier only matches 30% of your consumption with renewable generation, your physical emissions reflect that gap.
This matters for corporate procurement decisions. A manufacturing plant running steady baseload needs different renewable portfolios than an office building with sharp morning and evening peaks. A 24/7 data centre requires genuine around-the-clock generation, not annual certificates. The supplier renewable breakdown data reveals which retailers can actually deliver what they promise.
The Matched Clean Power Index
In the coming weeks, we'll publish the Matched Clean Power Index—the first independent ranking of UK energy suppliers by the clean power they deliver to their customers. Using half-hourly demand and generation data, we calculate matching scores for every major supplier.
Suppliers or other interested parties who'd like to preview the index ahead of publication can contact us at contact@matched.energy.