A REGO is a Renewable Energy Guarantee of Origin, a digital certificate that proves electricity came from a renewable source. Ofgem issues one for every megawatt hour of renewable power generated in the UK.

If you've seen a supplier advertise a "100% renewable" tariff, a REGO is the paperwork behind that claim. This guide covers how the scheme works, what certificates actually contain, and where the system falls short for businesses that want more than paper compliance.

What is a REGO

A REGO is a Renewable Energy Guarantee of Origin. It's a digital certificate that proves electricity came from a renewable source like wind, solar, or hydro. Ofgem, the UK energy regulator, issues one REGO for every megawatt hour (MWh) of renewable electricity generated.

If you've ever seen a supplier advertise a "100% renewable" tariff, a REGO is the paperwork behind that claim. The certificate creates a paper trail from the wind farm or solar installation all the way to your bill.

Here's the thing, though. The certificate and the actual electricity travel different paths. Your power comes from the grid, which mixes electricity from all sources. The REGO just proves that somewhere, at some point, a renewable generator produced the equivalent amount of clean power.

You might also hear about Guarantees of Origin, or GoOs. Same concept, different geography. GoOs operate across the EU, while REGOs are UK-specific and administered by Ofgem.

How the REGO scheme works

The journey from turbine to tariff involves four steps. Understanding each one helps you see what "renewable energy" actually means when it appears on your bill.

1. Renewable electricity generation

A wind farm, solar installation, or anaerobic digestion plant generates power and feeds it into the national grid. Meters record exactly how much electricity flows out, measured in megawatt hours. One MWh equals 1,000 kilowatt hours, roughly what a typical UK home uses in three months.

2. Certificate issuance by Ofgem

For every MWh generated, Ofgem issues one REGO certificate to the generator. Each certificate carries a unique identification number, making it traceable through the system. Think of it like a receipt that proves the renewable generation happened.

3. Supplier purchase and retirement

Energy suppliers buy REGO certificates from generators. More often, they buy from traders who sit between them. To claim the renewable attribute of that electricity, suppliers "retire" the certificates. Retirement means the certificate gets cancelled and can't be sold again.

This step matters. A supplier can buy power from a gas plant and match it with REGOs from a wind farm hundreds of miles away. The certificate and the electrons don't travel together.

4. Fuel mix disclosure to customers

UK suppliers report their fuel mix annually. By retiring REGOs, they can legally state that a portion of their electricity supply came from renewable sources. That's how "green tariffs" get their green credentials.

What information a REGO certificate contains

Each certificate carries specific data that identifies where the power came from and when. Here's what you'll find on one:

Generation source and technology

The certificate names the technology type. Wind, solar, hydro, biomass, or anaerobic digestion. This tells you what kind of renewable asset produced the power.

Location and capacity

It identifies the specific generating station and its installed capacity in megawatts. A REGO from a Scottish wind farm looks different from one issued to a Cornish solar installation. You can trace it back to a real place.

Generation period

REGOs specify the month the electricity was generated. This matters because certificates can be traded long after the power itself has been consumed. A supplier might retire a certificate from last winter to cover electricity you used yesterday.

Unique identification number

Every certificate has a traceable ID. Auditors use these to verify claims and prevent double-counting. Without this, the same renewable generation could be claimed by multiple parties.

Who issues REGOs in the UK

Ofgem administers the REGO scheme under the Electricity (Guarantees of Origin of Electricity Produced from Renewable Energy Sources) Regulations 2003. This legislation originally came from the EU Renewable Energy Directive and was retained in UK law after Brexit.

The scheme applies to all licensed renewable generators in Great Britain. Generators register with Ofgem, submit metering data, and receive certificates in return. The process is standardised, but what happens to those certificates afterwards varies widely depending on who buys them and how many hands they pass through.

How businesses use renewable energy guarantees of origin

REGOs serve three main purposes for commercial energy buyers. Understanding each one helps you evaluate whether a "green" tariff delivers what it promises.

Sustainability reporting and ESG claims

Companies use REGOs to demonstrate renewable energy procurement in annual sustainability reports. If your business publishes ESG disclosures (Environmental, Social, and Governance reporting), REGOs provide the documentation to back up renewable electricity claims. Investors and stakeholders expect this kind of verification.

Scope 2 emissions accounting

Under the GHG Protocol, businesses report Scope 2 emissions using either location-based or market-based methods. Scope 2 covers indirect emissions from purchased electricity.

• Location-based method: Uses grid-average emissions factors. Your emissions reflect the overall carbon intensity of the grid, regardless of what you bought.

• Market-based method: Uses supplier-specific data. REGOs prove you purchased renewable electricity, which can reduce your reported emissions to zero for that portion — though proposed GHG Protocol Scope 2 updates may require hourly matching.

Without REGOs, you're stuck with grid-average emissions factors even if you're paying for a green tariff.

Green tariff verification

Most "green" business energy tariffs bundle REGOs with standard electricity contracts. The supplier buys power on the wholesale market, purchases REGOs separately, and packages them together. The certificate backs the renewable claim on your bill.

This bundling is common practice. It's also why two "100% renewable" tariffs can have very different environmental impacts. The certificate proves origin, not impact.

How generators benefit from REGOs

For renewable generators, REGOs create an additional revenue stream on top of wholesale power sales. A wind farm sells electricity at the market rate, then sells the REGO certificate separately. Two products from one asset.

This matters for solar farms, wind operators, and anaerobic digestion plants looking to maximise returns. The certificate income adds to overall revenue, though prices fluctuate based on supply and demand.

Generators can sell certificates directly to suppliers or route them through intermediaries. Each layer in that chain takes a cut, which affects what the generator ultimately receives. A wind farm in Wales might see its REGO pass through three or four hands before it reaches the business that retires it.

The limitations of REGOs

REGOs do what they're designed to do: track renewable electricity origin. But they don't do everything businesses assume they do. Here's where the scheme falls short.

Certificates trade separately from power

A business can buy REGOs without buying the actual renewable electricity. The certificate and the electrons travel different paths. Your supplier might purchase power from a gas plant and match it with REGOs from a wind farm hundreds of miles away.

This creates a paper exercise. The renewable generation happened, but your purchase didn't directly fund it or consume it. You're buying proof of origin, not a direct connection to clean power.

No guarantee of additionality

Additionality asks a simple question: did your purchase cause new renewable capacity to be built?

Most REGOs come from existing generators that would operate regardless of certificate sales. The wind farm was already there. The solar installation was already producing. Buying a REGO rarely funds new projects.

If your goal is to accelerate the energy transition, REGOs alone won't get you there. They verify what exists. They don't create what's new.

Price volatility and market opacity

REGO prices swing based on supply and demand — from around £25 to under £1/MWh in recent years. Most businesses have no visibility into what their supplier paid for certificates or what margin sits on top.

That opacity makes it difficult to know whether you're getting value. Your supplier might pay £0.50 per certificate and charge you £3. You'd never know.

REGOs versus direct renewable procurement

There's another way to buy renewable electricity: connect directly to the generator. Here's how the two approaches compare:

Direct procurement removes the intermediaries between your business and the renewable asset. You see what you pay. The generator sees what they earn. No hidden margins, no certificate trading, no guesswork about where your money goes.

This approach works well for businesses that want genuine renewable credentials rather than paper compliance. It's more involved than signing a standard green tariff, but the transparency and cost savings can be significant.

A better way to buy renewable electricity

The traditional model adds layers between generators and businesses. Traders buy power, mark it up, and sell it on. Brokers take commissions. Suppliers bundle certificates with wholesale electricity and call it green.

Each layer adds cost without adding value. And none of them give you visibility into what you're actually paying for.

There's a different approach: connect businesses directly to renewable generators, remove the wholesale markup, and show exactly what you're paying and why. Generators earn more. Businesses pay less. Both sides see the real numbers.

That's the model tem built with RED. It replaces the trading desks with technology, cutting energy costs by around 30% while giving generators a direct route to business customers. No hidden margins. No certificate shuffling. Just power, priced fairly.

Let's talk.

FAQs about renewable energy guarantees of origin

How much do REGO certificates cost?

Prices vary based on market conditions and the technology type of the generating source. Suppliers rarely disclose what they pay, which adds opacity to green tariff pricing. Prices have ranged from under £1 to several pounds per MWh in recent years, depending on supply and demand.

Can a business purchase REGO certificates directly from a generator?

Technically, yes. In practice, most businesses lack the trading infrastructure and market access to do so. The majority purchase through suppliers or brokers who handle the procurement and add their own margins.

When do REGO certificates expire?

REGOs expire if not redeemed within a set period after issuance. Suppliers retire certificates within the compliance year to count toward their fuel mix disclosure. Unused certificates lose their value after the deadline passes.

What is the difference between REGOs and Guarantees of Origin?

Guarantees of Origin (GoOs) operate across the EU under similar principles. REGOs are the UK-specific equivalent, administered by Ofgem rather than EU member state bodies. Post-Brexit, the two schemes no longer interconnect. Since April 2023, UK suppliers cannot use EU GoOs for fuel mix disclosure, so a GoO from Germany can't back a UK green tariff.

Do REGO certificates count as carbon offsets?

No. REGOs certify the origin of electricity, not carbon reduction. They support Scope 2 emissions reporting but cannot substitute for verified carbon offset credits. Different mechanisms, different purposes. A REGO proves where your power came from. A carbon offset proves emissions were removed or avoided elsewhere.