A Renewable Energy Guarantee of Origin (REGO) is an electronic certificate showing that one megawatt-hour (MWh) of electricity was generated from a renewable source. Ofgem issues REGOs to accredited renewable generators in Great Britain on behalf of the Department for Energy Security and Net Zero, and in Northern Ireland on behalf of the Utility Regulator.
How it works
A generating station, such as a wind or solar farm, applies to Ofgem through the renewable electricity register. Once accredited, it receives one REGO for every MWh of eligible renewable output. Generators can sell the certificates, usually to electricity suppliers, either together with the electricity or separately from it.
The main use of REGOs is fuel mix disclosure. Licensed suppliers in Great Britain must tell customers each year what share of their electricity came from each source. To count electricity as renewable, a supplier redeems REGOs that cover that amount.
UK rules
| Point | Rule |
|---|---|
| Certificates per unit | 1 REGO per MWh |
| Administrator | Ofgem |
| EU certificates | Not recognised for GB fuel mix disclosure since 1 April 2023 |
| UK REGOs in the EU | Not recognised since 1 January 2021 |
Why it matters
REGOs are what allow a supplier to describe a tariff as 100% renewable. Critics point out that a supplier can buy certificates separately from the electricity, so a “green” tariff does not necessarily mean the supplier bought power directly from renewable generators or paid for new ones to be built.
Matching is also done over a whole year, so a REGO does not show when the renewable electricity was produced or used. In its July 2026 update to the clean flexibility roadmap, the government said adding more time detail to REGOs could help and that it will consider next steps, with a further update due in 2027.
Read more: Why switch to renewable energy? The benefits and the trade-offs.