Category: Compliance

Green Tariff vs Solar PPA: Which Renewable Claim Holds Up?

A REGO-backed green tariff and a solar PPA both let a UK business report renewable power. What each proves, what each costs, and when to use both.

A business that wants to say its electricity is renewable has two mainstream routes in the UK. One is a green tariff from its supplier. The other is a solar PPA, where a provider installs an array on the business's own roof and sells it the output. Both can support a renewable claim in a market-based Scope 2 figure, but they prove different things, cost money in different ways and carry different traps.

What a green tariff actually buys

A green tariff is an ordinary supply contract with a renewable claim attached. The electricity reaching your meter is the same grid mix as your neighbour's; what changes is the paperwork. Ofgem's guidance requires suppliers to hold REGO certificates for all the renewable electricity they supply under a green tariff, one certificate per megawatt-hour. Where a supplier goes further and claims an environmental benefit from the tariff, supply licence condition 21D adds requirements on evidence of supply, additionality and transparency.

Because REGOs can be transferred separately from the power, a supplier can buy its electricity in one market and its certificates in another. The claim is legitimate, but it is a claim about certificates, not about new generation.

What a solar PPA buys

A solar power purchase agreement buys the output of a specific array. On an on-site deal the panels sit on your roof and supply your building directly, at a price agreed for the term, with no capital outlay. If the array is new, your contract is the reason it exists, which is the additionality a certificate on its own cannot show.

The catch is that the array's REGOs do not automatically follow its power. Ofgem issues REGOs on an accredited station's gross generation, including the units your building uses, and the provider can sell them. The GHG Protocol is clear that a company consuming power from a facility whose certificates were sold forfeits the renewable claim on those units.

Side by side

When each makes sense

A green tariff suits a business that leases short-term, has no usable roof, or simply needs a renewable figure for its next report. A solar PPA suits an owner-occupier with daytime demand that wants a lower, known price for part of its electricity as well as a claim it can defend. It rarely has to be one or the other. An array usually covers only part of a site's demand, so a common combination is a solar PPA for the daytime share and a green tariff for the rest. How large that share can be is covered in how much of your electricity a solar PPA can cover.

What to ask for

• From a supplier: how many REGOs were redeemed against your supply, for which disclosure period, or an Ofgem cancellation letter naming your organisation.
• From a PPA provider: whether the array will be accredited for REGOs, and a clause transferring them to you or cancelling them in your name for the units you buy.
• For your report: both Scope 2 figures, location-based and market-based, as Scope 2 reporting with a PPA explains.

Sources: Ofgem — REGO Guidance for Generators, Agents and Suppliers, v4.0 (9 March 2026) (5.10, 6.21, 8.11); GHG Protocol — Scope 2 Guidance (2015), 6.4.1. Price and term bands are this site's indicative advisory ranges. Verified 27 Sep 2026.