Ben Brading 5 min read

The Renewable Energy Guarantees of Origin (REGO) scheme

The Renewable Energy Guarantees of Origin (REGO) system is a certification scheme in the UK that guarantees the source of renewable energy, providing confidence for consumers who pay for green energy tariffs.

A REGO certificate is issued for every 1 MWh (1,000 kWh) of renewable electricity generated. The certificates are sold by generators and purchased by energy suppliers, who retire the certificates when the equivalent amount of electricity is used by a green tariff customer.

The price of REGO certificates has increased dramatically over the past few years, rising from as low as 20p to over £20 for each certificate, making them a valuable commodity.

This article explains the REGO system in detail; here is what we cover:

How REGOs work
The rising price of REGOs
How the REGO system provides transparency
How energy suppliers use REGOs
How REGOs drive investment in renewables

How REGOs work

Ofgem, the UK energy regulator, administers the REGO system, providing an online platform that tracks all issuance, transfers, and retirement of REGO certificates.

To explain how the REGO system works, we will look at each step in the life cycle of a REGO certificate.

Issuance of REGO certificates

The REGO system allows any generator of renewable electricity to claim a REGO certificate for every MWh of electricity generated.

The scheme provides certificates to large-scale renewable generators, such as UK wind farms, and micro-generators, like small businesses with solar panels.

All renewable, non-fossil fuel sources of energy are eligible to receive REGO certificates. Below, we summarise the most common inclusions and exclusions under the scheme:

Electricity generation receiving REGOs:

Wind
Solar
Hydropower
Biomass (including the Drax Power Station)
Sewage treatment plant gas
Waste incineration
Anaerobic digestion

Electricity generation not receiving REGOs:

UK nuclear power (A zero-carbon energy source but not renewable)
Coal/Gas Power Stations (Directly use fossil fuels as a source of energy)

REGO trading and retirement

Since REGO certificates are standardised, there is a liquid market that facilitates trading between generators that receive REGOs and energy suppliers.

Licensed energy suppliers must purchase REGO certificates to prove the source of electricity supplied in their domestic and green business energy tariffs.

A supplier matches each MWh of electricity they supply under a green tariff to a REGO certificate, which is then retired. A retired certificate cannot be used again.

If you are interested in this process, read our full guide to how green business energy tariffs are delivered.

REGO shelf-life

All issued REGOs have a shelf life of 16 months from the month of generation, after which they are automatically cancelled.

The short shelf life is designed to maintain a strong connection between green electricity generation and usage, preventing energy suppliers from amassing a large stock of cheap REGOs in anticipation of future price rises.

The rising price of REGOs

As of January 2025, the price of a REGO certificate has risen dramatically, increasing from 20 pence in early 2020 to its current price of approximately £15. In this section, we’ll explain the two key factors contributing to this price rise.

Derecognition of European REGOs

Before 1 March 2023, Ofgem allowed energy suppliers to use European REGOs (called GoOs) as equivalent to REGOs generated in the UK.

The British national grid is interconnected with the European power grid through undersea cables, making purchasing renewable energy from the European continent possible.

However, under the previous system, energy suppliers could purchase cheap GoOs separately from imported power to verify renewable supplies to British customers. Ceasing to recognise the equivalency of GoOs has significantly increased the demand for British REGOs, raising their price.

Popularity of green tariffs

Consumers in Britain are increasingly opting for green domestic and business energy contracts.

Some suppliers, including Good Energy for Business, Ecotricity Business Energy, and Octopus Business Energy, only offer renewable electricity supply products.

As more consumers choose renewable power, suppliers need to purchase and retire REGOs more frequently, which has driven up their market price.

How the REGO system provides transparency

The REGO system facilitates transparency in the renewable energy market, giving consumers confidence in the original source of their power. We’ll summarise the two key ways the REGO system ensures this transparency.

Avoiding double counting of renewables

The REGO system is designed to prevent the double counting of certificates, which is a significant issue in other systems, such as carbon credits.

In the REGO system, the energy regulator, Ofgem, carefully verifies the issuance of new REGO certificates.

New certificates are only issued to verified renewable energy sources supported by actual meter readings.

Issued certificates can only be transferred and retired through an online platform. This ensures that transfers between parties are legitimate and prevents the sale of individual certificates to multiple suppliers.

Matching supplies against renewable purchases

Green energy sources, such as wind farms, share the same distribution infrastructure as non-renewable sources, meaning consumers have no easy way of knowing if their electricity has been purchased from green sources.

The REGO system provides a transparent and auditable process for suppliers to match renewable generation against supply.

Each time a MWh of renewable power is supplied to a customer under a green energy tariff, an energy supplier must retire a REGO certificate. Ofgem regularly audits the retirement process to ensure green tariffs are fully backed by renewable energy.

How energy suppliers use REGOs

In this section, we’ll explain how licensed domestic and business energy suppliers in the UK use the REGO system.

Fuel mix disclosure obligations

Licensed domestic and business energy suppliers must make an annual public disclosure of their fuel mix, which breaks down the sources of power generation they use to supply their customers into the following categories:

Coal
Gas
Nuclear
Renewable; and
Other

You can find the fuel mix disclosure for each supplier on their website.

Suppliers must use the REGO system to verify the renewable figure they include in the fuel mix disclosure.

Buying and retiring REGOs

Licensed energy suppliers use the REGO system to verify their renewable energy supplies. They retire a REGO certificate for each MWh of electricity delivered to a customer.

To do this, suppliers must actively obtain REGO certificates using the following methods:

Self-generation: The best business energy suppliers invest in their own renewable generation assets and, therefore, generate their own REGO certificates, which they can use directly with their customer base.
Power Purchase Agreements (PPA): Energy suppliers enter into long-term PPA agreements with renewable generators to purchase generated electricity and associated REGO certificates at an agreed price.
Open Market Purchases: Where a supplier has a shortfall of REGO certificates, they purchase them on the open market from brokers, other suppliers, or even businesses that sell their own generated REGOs.

How REGOs drive investment in renewables

The REGO certification system is a key component of the UK’s plans to decarbonise the national grid by replacing fossil fuels with renewable energy sources.

The REGO system allows any renewable energy generator to receive valuable REGO certificates. Most large renewable generators in the UK use Power Purchase Agreements to sell the electricity and associated REGOs they generate.

Recent rises in the value of a REGO certificate mean that REGO sales are enabling renewable investors to negotiate higher domestic and business electricity prices for the renewable power that they generate. Increases in the revenue available to renewable investors improve the return on investment for wind and solar projects, encouraging further investment.