A REGO certificate is Ofgem's official proof that 1 MWh of electricity came from a renewable source. Suppliers use these certificates to back their "green tariff" claims, but the system has a catch: the certificate can travel separately from the power itself.

This guide covers how REGOs work, what they contain, why businesses use them, and where the scheme falls short of genuine renewable procurement.

What is a REGO certificate and what does REGO mean

A Renewable Energy Guarantee of Origin (REGO) is a certificate that Ofgem issues to prove 1 MWh of electricity came from a renewable source. Suppliers use REGOs to back up their "green tariff" claims when they publish their annual Fuel Mix Disclosure. One certificate, one megawatt-hour of wind, solar, hydro, or biomass generation.

The idea behind the scheme is straightforward: give consumers a way to trace their electricity back to renewable generators. In practice, though, the system has a significant quirk.

REGOs can travel separately from the power itself. A supplier can buy electricity from any source, including gas-fired power stations, then purchase certificates on the side to call that supply "renewable." The electrons go one way. The paperwork goes another.

How UK guarantees of origin work

The REGO system moves through three stages. Following each stage helps explain why the scheme works the way it does, and where it starts to break down.

Generation and certificate issuance

When an accredited renewable generator feeds 1 MWh into the grid, Ofgem issues a matching REGO to the Renewables and CHP Register. The certificate ties to a specific month of production and a specific generating station.

Only registered generators qualify. A wind farm in Scotland, a solar park in Kent, an anaerobic digestion plant in Wales: each receives certificates for the renewable electricity it produces.

Trading between parties

Here's where things get interesting. Generators can sell their REGOs bundled with the electricity, or they can sell them separately. Selling certificates apart from the power is called "unbundling."

Unbundling is legal and common. A wind farm might sell its electricity to one buyer and its certificates to another. The certificate becomes a tradeable commodity, disconnected from the physical power it represents.

Redemption and fuel mix disclosure

Suppliers redeem, or cancel, REGOs to claim renewable electricity in their annual Fuel Mix Disclosure. This disclosure tells customers what proportion of a supplier's electricity came from renewable sources.

Once a supplier redeems a certificate, no one else can use it. The redemption deadline aligns with the compliance year, which runs from April to March.

Who issues and receives REGO certificates

Ofgem as scheme administrator

Ofgem runs the REGO scheme under the Electricity (Guarantees of Origin of Electricity Produced from Renewable Energy Sources) Regulations 2003. Ofgem maintains the register, issues certificates to generators, and tracks redemptions by suppliers.

Eligible renewable generators

Several technology types qualify for REGOs:

• Solar PV: Ground-mount installations and rooftop systems connected to the grid

• Onshore and offshore wind: Turbines of any scale, from single units to large wind farms

• Hydroelectric: Run-of-river schemes and reservoir-based generation

• Anaerobic digestion: Facilities that produce biogas from organic waste

• Biomass: Power stations burning wood, plant material, or other organic fuels

Suppliers and certificate redemption

Licensed electricity suppliers redeem REGOs to support their renewable tariff claims. Suppliers purchase certificates from generators, from brokers, or on the open market, then cancel them against their supply volumes.

What information a REGO certificate contains

Each certificate carries data that identifies where and when the electricity was generated. Here's what appears on a REGO:

This information creates a paper trail. Whether that trail connects to the electricity you actually use is a different question.

Why businesses use REGO certificates

Corporate sustainability reporting

REGOs provide documentary evidence for annual sustainability reports. When a business claims to use renewable electricity, auditors and stakeholders expect proof. Certificates fill that gap.

Scope 2 emissions accounting

Under the GHG Protocol, businesses can use REGOs for market-based Scope 2 reporting. This allows a company to claim zero-emission electricity on its carbon accounts, even if the physical grid mix includes fossil fuels at the time of consumption.

Stakeholder and supply chain expectations

Customers, investors, and partners increasingly ask for evidence of renewable procurement. British businesses' relationship with green energy is shifting fast, and a REGO-backed tariff provides a straightforward answer, though not always a complete one.

REGO vs ROC certificates

REGOs and ROCs often get confused. They serve different purposes.

ROCs, or Renewables Obligation Certificates, were designed to incentivise new renewable capacity by providing generators with meaningful revenue. REGOs only certify origin. They don't fund anything.

Why REGO certificates fall short

No direct link to renewable generation

A supplier can buy electricity from gas-fired power stations and purchase REGOs separately. The supply gets labelled "renewable" even though the physical power came from fossil fuels.

This isn't fraud. It's how the system works.

The unbundling problem

Because REGOs trade separately from power, a "100% renewable" tariff may fund no additional renewable generation – despite £1 billion spent annually on these certificates, according to Cornwall Insight. The generator already sold the electricity elsewhere. The certificate is just paperwork that changes hands.

You might be thinking: so what's the point? Fair question. The certificate proves that renewable electricity was generated somewhere, at some point. It doesn't prove that your money supported that generation.

Minimal financial benefit to generators

REGO prices remain low, with trades reported as low as £0.30–£0.77 per MWh. Selling certificates provides little meaningful revenue to renewable projects. REGO prices remain low, often just a few pence per MWh. Selling certificates provides little meaningful revenue to renewable projects. For a wind farm or solar park, the real money comes from selling the electricity itself, not the certificates.

How to spot greenwashing in energy supply

Questions to ask your supplier

When a supplier claims "100% renewable," a few questions reveal what that claim actually means:

• Where does the power come from? Ask for specific generators, not vague references to "renewable sources"

• Do you own generation or buy REGOs separately? Unbundled certificates signal a weaker claim

• What percentage is backed by PPAs? Direct contracts with generators indicate genuine renewable sourcing

Warning signs in renewable claims

Some red flags to watch for:

• Vague language like "green energy" without naming generators or technology types

• The cheapest tariff in market while claiming 100% renewable

• No information about where the electricity actually comes from

If a deal sounds too good to be true, it probably involves unbundled certificates bought on the cheap.

Verifying actual generator relationships

You can request your supplier's Fuel Mix Disclosure data. Ask whether the supplier contracts directly with generators or simply purchases certificates on the open market. The answer tells you a lot about what "renewable" actually means in their context.

Alternatives to certificate-based renewable energy

Power purchase agreements

A Power Purchase Agreement, or PPA, is a direct contract between a buyer and a renewable generator. The UK doubled PPA volumes to 1.4 GW in 2024, as buyers commit to purchasing output for a fixed term, giving generators revenue certainty. This creates a genuine financial relationship with renewable generation, not just a paper trail.

Direct generator matching

Some suppliers match business consumption with output from specific, named generators in real time or half-hourly. This creates traceability that certificates alone cannot provide. You know which wind farm or solar park powered your site, and when.

Sleeved and virtual PPAs

Sleeved PPAs route generator output through a licensed supplier to your meter. Virtual PPAs use financial settlement without physical delivery. Both create direct commercial relationships with generators, which makes for a stronger claim than unbundled REGOs.

What genuine renewable procurement looks like

Genuine renewable energy means knowing which generator produced the power and when. It means revenue flows to the project, not just certificate brokers. It means transparency in pricing and traceability in supply.

Businesses that want to decarbonise meaningfully look beyond certificates to direct relationships with generators. They ask harder questions. They demand visibility into what they're paying and why.

That's the difference between paperwork and progress.

Let's talk.

FAQs about REGO certificates

How much does a REGO certificate cost?

REGO prices fluctuate but typically trade at a fraction of the wholesale electricity price. Expect just pence per MWh, which makes certificates inexpensive compared to the power itself.

Can a business buy REGO certificates directly from Ofgem?

No. Businesses cannot purchase REGOs directly. Only accredited generators receive them, and only licensed suppliers can redeem them for Fuel Mix Disclosure purposes.

Do REGO certificates expire?

REGOs carry a redemption deadline tied to the fuel mix disclosure compliance year. Certificates not redeemed within the relevant period lose their value for disclosure purposes.

Are REGO certificates the same as carbon offsets?

No. REGOs certify that electricity came from renewable sources. Carbon offsets represent emissions reductions or removals elsewhere. They serve different purposes and cannot substitute for each other.

How can a business verify that a supplier holds valid REGO certificates?

Request your supplier's Fuel Mix Disclosure or ask for evidence of REGO redemption from the Renewables and CHP Register. Legitimate suppliers provide this information without hesitation.