Energy data

Who Retires Britain’s Renewable Certificates

Contents

Who redeems Britain’s renewable certificates

When a wind farm, a solar array or a biomass plant generates a megawatt hour, Ofgem issues it a Renewable Energy Guarantee of Origin — a REGO. The certificate is a record that the generation happened, and it can be bought and sold on its own, apart from the electricity it describes.

A supplier that wants to call its supply renewable buys certificates covering what its customers used and redeems them. Redemption is the act that closes the claim: once a certificate is redeemed nobody else may count it. Ofgem publishes every one of them, and the table below is what that register says.

Who redeemed certificates for 2025/26

The 15 largest of 55 certificate holders that redeemed anything against generation in this Fuel Mix Disclosure year. Redeeming is the act that lets a supplier describe supply as renewable; the other statuses further down are not that.

Certificate holder, as published	Certificates redeemed	Share of the year
Octopus Energy Limited	24,857,793	21.0%
British Gas Trading Ltd - Supplier - SUP0008543	14,614,326	12.4%
Drax Energy Solutions Limited (Supplier)	13,464,918	11.4%
EDF Energy Customers Ltd	9,194,848	7.8%
SmartestEnergy Ltd - Supplier - SUP0008573	6,795,365	5.7%
TotalEnergies Gas & Power Limited	6,057,580	5.1%
SSE Energy Supply Ltd	5,568,533	4.7%
ENGIE POWER LIMITED	4,239,380	3.6%
Npower Commercial Gas Ltd	4,192,966	3.5%
E.ON Next Energy Limited	3,490,900	3.0%
Brook Green Trading Limited	3,187,502	2.7%
Bryt Energy Limited	3,026,471	2.6%
Ecotricity Limited	2,612,693	2.2%
SHELL ENERGY UK LIMITED	2,405,751	2.0%
Pozitive Energy Ltd	2,276,678	1.9%

These are the legal entities that hold the certificates, spelled as the register spells them. One corporate group can hold under several, and this page does not merge them — doing so would need an effective-dated record of which entity belonged to which brand in which year, which does not exist here. Nor is a share of certificates a share of households: the register covers business supply too and carries no customer denominator at all.

What those certificates were generated by

Offshore wind: 39.2%46,333,237 certificates
Onshore wind: 22.6%26,685,725 certificates
Biomass: 21.3%25,225,968 certificates
Solar PV: 8.0%9,447,195 certificates
Hydro: 3.6%4,221,280 certificates
Biodegradable: 3.0%3,581,254 certificates

Every technology in this list is renewable under the scheme’s own rules. That includes burning things: a certificate from a biomass plant and one from an offshore wind farm are interchangeable when a supplier redeems them, and a tariff label does not distinguish between them.

Contains public sector information licensed under the Open Government Licence v3.0. Source: Ofgem Renewable Electricity Register. Renewable Electricity Register: REGO certificates public report

What a redeemed certificate proves

It proves that somewhere on the system, in a stated month, a stated quantity of renewable electricity was generated, and that this company — and no other — is allowed to count it. That is a real and auditable thing, and it is worth having. It is also less than most readers assume.

It does not prove that the supplier caused the generation. The certificate is created by the generating, not by the buying; a supplier with no wind farms and no long-term contracts can buy certificates on the open market long after the electricity was made and sold. The register shows the gap rather than leaving it to argument.

Four things the register records

Holders who redeemed, out of every holder: 55 of 5,063Most holders are generators sitting on their own output. Redemption is a supply-side act, done by a few dozen companies a year, and it happens after the electricity has been sold.
Days between the generation and the claim: 92 to 427Counted from the end of the month the electricity was generated in. Not one certificate in this year was redeemed in that month, and 21.8% of them were redeemed more than a year afterwards.
Certificates that expired unclaimed: 5.8%70,071,622 certificates across the register lapsed with nobody using them. That renewable electricity was generated and reached the grid regardless, which is the clearest sign that the certificate and the generation are separate things.
Redeemed against a claim, this year, by combustion: 21.3%Biomass alone. Under the scheme it is renewable and the resulting certificate is identical to a wind one, so a “100% renewable” label covers both without saying which.

How every issued certificate has ended

Three shares of the same denominator, and deliberately not a total. Redeemed backs a fuel-mix claim; retired is withdrawal without one; expired lapsed unused. The remainder is still in circulation.

Redeemed: 79.2%; 956,978,006
Retired: 11.3%; 136,990,879
Expired: 5.8%; 70,071,622

Counted over 1,208,707,489 certificates the register records as issued. A further 8,840,080appear in the file with no issue date at all — they were never issued, they are absent from Ofgem’s own published totals, and they are excluded here for the same reason. Excluding exactly those is what makes these figures agree with the publisher’s technology-and-country table cell for cell.

This source is registered but not yet switched on for unattended refresh, so these are stored figures rather than a live read of the register.

Contains public sector information licensed under the Open Government Licence v3.0. Source: Ofgem Renewable Electricity Register. Renewable Electricity Register: REGO certificates public report

Redeemed, retired, expired

The register gives every certificate a status, and three of them are endings that sound alike and mean different things. A certificate is redeemedwhen it is used to back a Fuel Mix Disclosure claim — that is the retirement a green tariff rests on. It is retired when it is withdrawn from circulation without such a claim. It has expired when it lapsed unused.

Adding retired to redeemed is the single easiest way to overstate what suppliers claimed, because “retired” is the word the voluntary-market literature uses for what this scheme calls redemption. Every figure on this page is scoped to one status and none of them is summed with another.

Why these are company names, not brands

The register publishes the legal entity that holds a certificate, and sometimes appends its supply licence reference. Those entities are not consumer brands. One group can hold under several — with materially different volumes in each — and entities change hands part-way through a year.

So this page prints what Ofgem prints. Grouping the entities into brands would need a record of which entity belonged to which brand on which date, and inventing one would produce a figure that looks correct for every supplier and is wrong for the ones that restructured. Beside a green-claim number, that is the one place it must not be wrong. If the grouping is ever done here, it will be stated on the page as an editorial decision rather than performed quietly in a join.

What this page counts, and what it leaves out

Only certificates the register records as issued. A few hundred rows in the published file carry no issue date at all: those certificates were never issued, they are absent from Ofgem’s own published totals, and including them here would put this page out of step with the publisher by millions of certificates. Excluding exactly those — not the statuses that happen to correlate with them — is what makes these figures match Ofgem’s technology-and-country table cell for cell.

Nothing certificate-level is held. The register runs to hundreds of thousands of rows a day and is aggregated on the way in, to holder, status, output period, technology and country. And nothing here is matched to a supplier, a tariff or a customer count.

For what all of this adds up to for a household — what the electricity nobody claimed is actually made of — see what a green tariff actually buys.

Frequently asked questions

What is a REGO?

A Renewable Energy Guarantee of Origin. Ofgem issues one for each megawatt hour of eligible renewable generation, and it is a tradable record that the generation happened. A supplier that redeems enough REGOs to cover what its customers used may describe that supply as renewable in its annual Fuel Mix Disclosure.

Does redeeming a certificate mean the supplier caused renewable generation?

No. A REGO is created by the act of generating and can be sold separately from the electricity itself, so redeeming one is a claim on generation that already happened rather than a cause of it. The register shows this directly: certificates are redeemed months and sometimes years after the electricity was made, and a substantial number expire with nobody claiming them at all — that generation still reached the grid.

Is “Redeemed” the same as “Retired”?

No, and it is the easiest mistake to make with this register because the two words are near-synonyms in ordinary English. A certificate is Redeemed when it is used to back a Fuel Mix Disclosure claim. It is Retired when it is withdrawn from circulation without such a claim. Expired means it lapsed unused. This page keeps all three apart, because adding Retired to Redeemed overstates what suppliers claimed by roughly half again.

Why are the names on this page not the brands I recognise?

Because Ofgem publishes the legal entity that holds the certificate, sometimes with its supply licence reference attached. One corporate group can hold under several entities with different volumes in each. Matching those to consumer brands needs a record of which entity belonged to which brand in which year, and this site does not have one, so the register’s own wording is shown instead of a guess.

Does a big share of certificates mean a big share of customers?

No. The register covers business and industrial supply as well as households, and it carries no customer numbers at all. A share here is a share of certificates redeemed, and nothing about it can be read as market share.

What is a compliance year?

The Fuel Mix Disclosure year, which runs from 1 April to 31 March. This page names it by the calendar year it opens in, so 2024/25 means generation between 1 April 2024 and 31 March 2025. Certificates keep being redeemed against a year after it ends, so the most recent year on this page will usually still be filling up.

Where does this data come from?

Ofgem’s Renewable Electricity Register, which publishes the full certificate register as a public report. This page holds it only in aggregate — by holder, status, output period, technology and country — and never certificate by certificate. It is published under the Open Government Licence.