REGO certificates are the proof of origin behind every megawatt hour of renewable electricity generated by registered wind, solar, hydro and other renewable sources in the UK.
This guide explains what they are, how the scheme works from generation through to a business’s supply, what they prove, how they’re traded and priced, and how a business can verify one.
What is a REGO certificate?
A Renewable Energy Guarantee of Origin (REGO) is a certificate confirming that a specific volume of electricity was generated from a renewable source and fed into the grid.
One REGO is issued for every megawatt hour (MWh) of renewable electricity generated, and suppliers retire these certificates to back any green electricity they sell to customers.
This system addresses the fact that the physical electricity itself can’t be traced from a specific generator to a specific business once it enters the grid.
How does the REGO scheme work?
The REGO scheme exists to reward renewable generators for the electricity they produce and to give businesses a way to verify that the electricity they buy is genuinely backed by renewable generation.
Here’s how it works, from generation through to a business receiving certified green electricity:
1. A renewable generator registers with the scheme
Generators using an eligible renewable source must register for an account on Ofgem’s Renewable Electricity Register and apply for accreditation before they can receive REGOs. Eligible sources include:
- Wind (onshore and offshore)
- Solar
- Hydroelectric
- Biomass
- Biogas and landfill gas
- Geothermal
- Wave and tidal
2. Renewable electricity is generated and metered
The generator produces electricity and feeds it into the grid, with output metered and reported to Ofgem to support the volume of REGOs claimed.
3. Ofgem issues REGOs based on metered output
One REGO is issued per megawatt hour (MWh) of eligible renewable electricity generated, based on the metered output reported by the generator.
Each REGO is tagged with key metadata such as the type of renewable, the generating station, place of origin, etc.
4. REGOs are held and traded via the Renewable Electricity Register
Issued REGOs sit on the Renewable Electricity Register, Ofgem’s central system for tracking them.
Generators can transfer them to other account holders (typically business energy suppliers) either bundled with the electricity under a power purchase agreement (PPA), or sold separately from the electricity generated.
The transfer process on the register is the same either way, and in both cases REGOs add value for the generator, either priced into the PPA or earned through a separate sale.
5. Suppliers use REGOs to back green supply
A supplier looking to offer a green tariff purchases REGOs equivalent to the volume of electricity it plans to supply as renewable.
The cost of these certificates is built into the price of the green contract, so it can show up as a small premium on the unit rate compared with a standard tariff. This is one of several factors that form business electricity prices.
6. REGOs are retired against supply
Once used to back a specific volume of electricity supplied, REGOs are retired, permanently removing them from circulation so the same certificate can’t be used to back more than one claim of green supply.
REGOs that aren’t retired expire 15 months after the electricity was generated.
7. The business receives certified green electricity
The business that is under a green electricity contract is supplied with electricity from the grid as normal, but its usage is backed by an equivalent volume of retired REGOs, allowing the supplier to certify that volume as renewable.
What does a REGO certificate prove?
A REGO certificate proves that a specific volume of electricity was generated from a renewable source, and records the details needed to verify that claim. Each certificate includes:
- The type of renewable used: Which affects how the certificate is later valued.
- The generating station: Identifying exactly where the electricity was produced.
- The country of origin: Either Great Britain or Northern Ireland (since Brexit, EU REGOs are not recognised in the UK).
- The generation period: The specific timeframe the electricity was produced in.
- A unique reference number
Together, this proves that a matching volume of renewable electricity was generated and fed into the grid. It does not prove that the specific electrons a business consumes came directly from that generator, since electricity from all sources mixes together once it enters the grid.
How are REGOs used for Fuel Mix Disclosure?
Fuel Mix Disclosure (FMD) is a requirement for all licensed electricity suppliers in Great Britain to publish the mix of fuels, such as coal, gas, nuclear, renewable, and other sources, used to generate the electricity they supplied over the previous year.
REGOs are the evidence suppliers use to support the renewable percentage shown in this disclosure. A supplier must hold and retire enough REGOs to cover the volume of electricity it claims as renewable across its whole supply.
Businesses are free to compare business energy suppliers by how their fuel mix and green credentials stack up.
Can REGO certificates be traded separately from electricity?
Yes, every REGO can be unbundled from the renewable electricity it represents. It can also be bundled together with it, either through a PPA with a renewable generator or by a supplier producing REGOs from its own renewable generation.
Bundled REGOs
The certificate comes together with the electricity, either from a named renewable generator via a power purchase agreement (PPA) or from renewable assets the supplier’s group owns itself, such as its own wind or solar farms.
Where a supplier owns the generation, the REGOs are issued on the register and then redeemed to back its green tariffs and fuel mix disclosure.
This gives a clearer, more traceable link between the renewable source and the electricity a business receives, but usually involves longer-term commitments and less flexibility than buying REGOs unbundled.
Unbundled REGOs
The certificate is bought separately from the electricity it represents. A generator can sell its power to one supplier, and the associated REGO to a completely different one to back a green claim.
This is usually the cheapest and most flexible option, but it means the supplier’s actual electricity may come from any source on the wholesale market, with the REGO purchased to support the claim.
What determines REGO certificate price and value?
Ofgem doesn’t set a price for REGO certificates. They trade on a secondary market, where price is shaped by several factors, much like any other tradeable commodity:
- Supply and demand: REGO prices rise and fall with the balance between demand for green tariffs and the volume of renewable generation available.
- Generation period: Each REGO is tied to the month its electricity was generated and must be cancelled within 16 months. Suppliers use them against the Fuel Mix Disclosure year (April to March) in which the power was generated, so certificates close to the 1 July redemption deadline typically trade lower than more recent stock.
- Renewable technology: REGOs from technologies such as wind, solar or hydro tend to command a higher price than those from sources like biomass or landfill gas, as buyers often see them as more credible.
- Route to market: The quoted market price only applies to REGOs traded separately from electricity. Under a PPA, REGO value is usually built into the wider contract terms rather than set by the market at the time of transfer.
How to check a REGO certificate
Businesses may want to verify the REGOs a supplier retired to confirm their authenticity for sustainability reporting, or simply to satisfy due diligence before signing or renewing a contract marketed as renewable.
Since most businesses normally don’t have direct account access to Ofgem’s Renewable Electricity Register (RER), checking a REGO requires requesting it from the supplier and cross-referencing it where possible. Depending on what needs verifying, this can include:
- Certificate details: Requesting the unique reference number, technology type, generating station, and generation period behind a specific green claim.
- Generation period: Confirming this aligns with the electricity being billed, since REGOs are tied to a specific timeframe and expire 15 months after generation.
- Generating station accreditation: Cross-checking the named station against Ofgem’s public reports on the Renewable Electricity Register, which list generating stations accredited under the scheme.
- Retirement status: Confirming the REGOs have actually been retired against the business’s supply, since a certificate only counts as used once retired, and retired REGOs can’t be reused elsewhere.
- Supporting documentation: Requesting certificate serial numbers and retirement confirmation where the REGOs are being relied on for sustainability reporting, since frameworks such as SECR, CDP, or RE100 typically require this level of evidence.
REGO FAQs
Our business energy experts answer commonly asked questions regarding REGO certificates:
What does a 100% REGO-backed electricity tariff mean?
It means the supplier holds REGOs equivalent to the entire volume of electricity supplied under that tariff, allowing all of it to be certified as renewable.
It doesn’t necessarily mean the electrons themselves all came from renewables, as these can’t be separated once in the grid. It does mean an equivalent volume of renewable electricity was generated and fed into the grid.
This differs from a power purchase agreement (PPA), where a business contracts directly with a named renewable generator, which gives a clear, traceable link to a specific source rather than relying on certificates alone.
How can a business be 100% REGO-backed if it consumes a fraction of a megawatt hour?
The supplier needs to ensure that every megawatt hour of electricity supplied is backed by a REGO, so fractional usage is simply rounded up to the nearest whole MWh when certificates are retired against it.
In practice, suppliers aggregate this across their entire customer base, buying and retiring REGOs in bulk to cover the combined volume needed for all their green tariff customers, rather than matching a single certificate to one business’s individual usage.
Can one MWh of renewable electricity receive more than one REGO?
No, one REGO is issued per MWh of eligible renewable output, and once a REGO is retired against a claim of green supply, it’s permanently removed from circulation and can’t be reused or reissued for the same generation.
Are UK REGOs recognised in the EU?
No. Since the UK’s official exit from the EU’s internal energy market arrangements on 1 January 2021, the EU no longer recognises UK REGOs, and vice versa.
This means electricity imported through interconnectors, even if it was generated from renewable sources abroad, can’t be backed by REGOs or used to support a green tariff claim in Great Britain.
Are REGOs the same as carbon offsets?
No. A REGO certifies that a specific volume of electricity was generated from a renewable source; it doesn’t represent a reduction or removal of carbon emissions elsewhere, which is what a carbon offset does. The two are separate mechanisms: REGOs relate specifically to the origin of electricity, while offsets relate to compensating for emissions through separate projects.
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