What Is a REGO Certificate, and Does a Green Tariff Count as Renewable Energy?

What a REGO certificate is

A REGO is a Renewable Energy Guarantee of Origin: a certificate showing that electricity was generated from renewable sources. Ofgem's REGO page says one certificate is issued per megawatt hour of eligible renewable output. Ofgem administers the scheme for generation in Great Britain on behalf of the Department for Energy Security and Net Zero, and for Northern Ireland on behalf of the Utility Regulator.

The same page says the main use of REGOs in Great Britain and Northern Ireland is fuel mix disclosure: licensed suppliers have to tell customers the mix of fuels used to generate the electricity they supplied, and REGOs are how a supplier shows the renewable share. It also notes that EU Guarantees of Origin no longer recognise UK REGOs as of 1 January 2021, and that from the disclosure period starting 1 April 2023 EU Guarantees of Origin are no longer recognised for Great Britain fuel mix disclosure. A certificate from another market is therefore not interchangeable with a UK REGO for a UK supply claim.

What a green business electricity tariff does

When a supplier sells a green or renewable tariff, it commits to cover the electricity you use with REGOs. Your electrons are unchanged: the power reaching the meter is the same grid mix as before. What changes is the supplier's disclosure and, if you account for emissions on a market-based basis, the emission factor you can apply to that electricity. If you want power that is physically generated on your own site, that is a different route: on-site solar, storage or an on-site power purchase agreement.

Ofgem's page does not give a price for a certificate, tell you the age of the certificates a supplier uses, or say whether they come from new or existing plant, so those are questions for the supplier, not facts you can assume from the word "green".

Does it count as renewable energy for your business?

That depends on which claim you are making, and the three are easy to blur.

• Physical. No. A REGO-backed tariff does not change the electricity delivered to your site.
• Market-based Scope 2. Often yes, if you report on that basis. The GHG Protocol Scope 2 Guidance sets eight quality criteria that contractual instruments must meet, so the certificates need to qualify, not merely exist.
• New capacity. A tariff backed only by certificates from existing plant does not by itself fund any new generation. A PPA with a new-build project is the route that can.

For UK reporting, the government's environmental reporting guidance records, in its 29 March 2019 update, that for organisations choosing not to dual report, location-based reporting is "still our preferred approach". If you report both figures, a REGO-backed tariff lowers the market-based one and leaves the location-based one where it was, so the gap stays visible. Where this matters for your obligations, see the net zero for business guide.

Worked arithmetic: how many certificates is 100% cover?

This is an illustration with stated assumptions, not a quote or a result from any site. Suppose a site uses 500 MWh of electricity a year. One REGO covers one MWh, so 100% cover needs 500 certificates a year. If rooftop solar on the same site supplies 150 MWh of that use directly, the balance is 350 MWh, so a tariff would need to retire 350 certificates to cover the rest. The certificate count scales one-for-one with the megawatt hours you claim, whatever the tariff is called.

Questions to put to a supplier before you sign

1. Are the certificates UK REGOs, and does the tariff cover 100% of your annual volume or only a share?
2. Which technologies and which country do the certificates come from, and from which year of generation?
3. Are the certificates retired on your behalf, in your organisation's name, or at supplier level?
4. What is the price difference against a standard tariff, over the full contract term?
5. What will you be allowed to say in a report or on your website, and does the supplier put that in writing?

Where a green tariff fits in a business plan

Buying certificates is the last step, not the first. The sensible order for most sites is to cut waste, generate on site where the roof and load justify it, electrify heat and transport, and then buy what you cannot generate. A tariff is one of four routes compared in our guide to renewable energy for businesses, and the step-by-step guide covers the sequence. For a tenant on a short lease with no roof to use, a REGO-backed tariff is often the practical option, provided the claim you make is the claim it supports.

Questions people ask

What is a REGO certificate?

A certificate that one megawatt hour of electricity was generated from an eligible renewable source. Ofgem administers the Renewable Energy Guarantees of Origin scheme for generation in Great Britain on behalf of the Department for Energy Security and Net Zero, and for Northern Ireland on behalf of the Utility Regulator.

Is a green business electricity tariff renewable energy?

It is a contractual claim, not a physical one. The supplier backs your usage with REGO certificates, which supports a market-based Scope 2 figure and the supplier's fuel mix disclosure. The electricity reaching your meter is the same grid mix, and a tariff backed only by certificates does not by itself add new renewable capacity.

What is the difference between a REGO and a PPA?

A REGO is a certificate. A power purchase agreement is a contract to buy power from a named generator. A PPA can bring certificates with it, but who keeps them is a term to check in the contract, so ask before you claim the renewable output.

Sources and last checked

Checked on 20 October 2026. Renewable Energy Guarantees of Origin (REGO), Ofgem; Scope 2 Guidance, GHG Protocol; Environmental reporting guidelines, gov.uk. This guide names no supplier and ranks none. Schemes and guidance change; the official pages are the authority if they disagree with this one.