The short version: “100% green” on an Irish bill means your supplier matched your annual usage with renewable certificates — not that green electrons were piped to your house. One certificate (a Guarantee of Origin) represents 1 MWh generated from renewables anywhere in the EEA. The certificates are real and audited; the thing they prove is where money and credit went, not where your electricity came from.
If you want green claims ranked — all nine suppliers, scored on evidence and price — that is best green electricity. This page is the manual behind it. And a note for the avoidance of doubt: matched.ie is not a CRU-accredited comparison site — the accredited comparators are listed on cru.ie.
Why is “green electricity” a claim about money, not electrons?
Ireland has one electricity grid. Wind farms in Kerry, gas turbines in Dublin, hydro on the Shannon and every solar panel in the country feed their output into the same network, where it blends instantly and completely. ESB Networks delivers that blend to every home in the state, whichever name is on the bill, and there is no mechanism — physical or commercial — that routes particular electrons to particular customers. The householder on a “100% green” plan and their neighbour on a standard plan draw identical electricity at every moment of every day.
So a green tariff cannot be a promise about the electricity itself. What it can honestly be is a promise about the money: that the revenue from your bill was used to buy renewable output, or renewable certificates, in the same quantity as your consumption. That is a real and checkable claim — it just lives in accounts and registries, not in the wires. The whole subject becomes much easier once you accept that framing: green electricity in Ireland is a question about what your euros fund, and the only interesting differences between suppliers are differences in the quality of the proof.
The proof comes in two official flavours. The first is the annual fuel-mix disclosure, calculated for every licensed supplier on the island under Single Electricity Market rules and published by the SEM Committee (the paper trail lives at semcommittee.com). The second is the certificate system that feeds it — and that is where the Guarantee of Origin comes in.
What is a Guarantee of Origin and how does one reach your bill?
A Guarantee of Origin (GO) is an electronic certificate issued to a renewable generator for each megawatt-hour it produces — 1 GO = 1 MWh. The certificate exists so that renewable output can be claimed exactly once: a GO used in one supplier’s fuel mix cannot be used in another’s, which prevents double counting. Crucially, GOs are tradeable across the whole European Economic Area and are explicitly allowed to travel separately from the electricity itself. A certificate can be sold to an Irish supplier by a generator that has no cable connection to Ireland at all.
Here is the full journey, from turbine to the badge on your bill:
| Step | What happens | Where |
|---|---|---|
| 1. Generation | A renewable generator — a wind farm in Ireland, or equally one elsewhere in the EEA — produces a megawatt-hour and feeds it into its local grid, where it blends with everything else. | The generator’s own grid |
| 2. Certificate issued | The issuing body in that country creates one GO for that MWh in an electronic registry. The electricity and the certificate now lead separate lives. | National GO registry |
| 3. Certificate traded | The GO is sold — directly or through brokers — via the hub run by the Association of Issuing Bodies, which connects registries across Europe. An Irish supplier can buy certificates from anywhere in the scheme. | EU-wide certificate market |
| 4. Certificate cancelled | The supplier retires (“cancels”) GOs equal to its customers’ consumption. A cancelled certificate can never be used again — this is the audited, single-use heart of the system. | Supplier’s registry account |
| 5. Disclosure | The market operator counts every supplier’s cancelled certificates and generation attributes and calculates its disclosed fuel mix, which must then appear on your bill. | SEM fuel-mix disclosure → your bill |
Notice what the system does and does not do. It does guarantee that somewhere in Europe, renewable megawatt-hours equal to your usage were generated and credited to your supplier alone. It does not connect those megawatt-hours to your house, your country, or even your year’s weather. Both halves of that sentence matter, and most green marketing quietly relies on you hearing only the first.
Why can supplier badges look greener than the Irish grid?
Because certificates travel and electrons do not, the sum of what suppliers claim can exceed what the island generated. The official numbers make the point better than any argument. In the SEM Committee’s disclosure for 2024, the all-island fuel mix — with every certificate already counted — was 62.35% renewable, up from 61.01% in 2023, alongside 34.72% gas. Getting there involved importing 20,259,452 GO certificates into the all-island market in that one year, an 11.7% increase on 2023. The regulator’s own paper is blunt that the disclosed mix is “not an indication” of actual generation by fuel type, because suppliers may claim renewable attributes generated outside the market entirely.
Set the individual disclosures against that average and you can see the certificate machine at work:
Disclosed 2024 renewable share by supplier licence (Republic of Ireland), from the SEM Committee’s all-island fuel-mix disclosure. Four brands we track — SSE Airtricity, Bord Gáis Energy, Pinergy and Flogas — disclosed exactly 100% renewable and an emissions factor of 0.00 gCO2/kWh. The island as a whole, certificates included, managed 62.35% and 163 g/kWh. Nobody is lying: the 100% rows simply held enough cancelled certificates to cover their sales. But a bar that reads 100% while the grid reads 62.35% is telling you about a certificate portfolio, not a power source.
The same table holds a stranger result at the bottom — a supplier that buys real Irish renewable output and discloses a mix that looks worse than the average. Before we get to that paradox, it helps to define what stronger and weaker green evidence actually looks like.
What counts as proof? The evidence ladder, defined
Our green ranking scores suppliers on this ladder; here we just define the rungs. Each one is a different answer to the question “what did my money fund?” — and each is verifiable in a different place.
| Type of claim | What it means | How you would verify it |
|---|---|---|
| Direct Irish generation purchase | The supplier buys output straight from named Irish renewable generators — your bill revenue goes to those projects. The strongest link money can have to Irish turbines and rivers. | The supplier names its generators; in Community Power’s case, community wind and hydro projects it grew out of. |
| Supplier-owned generation + GO matching | The group behind the brand builds and runs renewable generation here (SSE and Energia’s parent both operate Irish wind farms), but the household “100%” badge is still delivered by annual certificate matching. | Group annual reports for the hardware; the SEM disclosure for the badge. |
| Certificate matching alone | The supplier cancels GOs equal to its sales. The certificates may come from anywhere in the EEA and may have nothing to do with Irish generation. | The disclosed fuel mix on your bill and in the annual SEM paper. |
| Verified green product | A specific plan marketed as green by a supplier whose overall annual mix is not 100% renewable — the case the CRU’s Green Source Product Verification framework exists for. The product’s claim must be independently verifiable rather than simply asserted. | The CRU’s verification framework; ask the supplier for the product-level fuel mix, which you are entitled to request. |
| No claim | The supplier holds no certificates and markets no badge, so its disclosure drifts towards the residual mix — the browner-looking pool of unclaimed electricity. The power at the socket is identical. | Nothing to verify — which is its own kind of honesty. |
Note that this is a hierarchy of evidence, not of virtue. A certificate-matched badge is a real, audited, single-use claim — rung three is not greenwashing. It is simply a weaker statement about where your money went than rung one, and the marketing rarely admits the difference.
Why does the greenest supplier look the brownest on paper?
Here is the best single illustration of how the accounting works — and the reason you should never judge a supplier by its disclosed percentage alone. Community Power, Ireland’s community-owned supplier, buys its electricity from small Irish community and micro wind and hydro generators; the company grew out of the Templederry community wind farm in Tipperary. By the money test, no supplier in the market has a stronger green story. Yet its disclosed 2024 fuel mix was 43.74% renewable with an emissions factor of 247 gCO2/kWh — below the all-island average, and miles behind the 100%/0.00 rows of the certificate buyers.
The explanation is the machinery you have just read about. Community Power deliberately refuses to buy Guarantees of Origin — its position is that Irish community generation should not need imported certificates to prove itself. But the disclosure calculation only counts certificates and registered attributes. Refuse the paperwork and the formula fills the gap from the unclaimed pool, so the disclosed mix drifts towards the residual — no matter whose turbines your money actually paid for. The result is the paradox on the bar chart above: the supplier most directly funding Irish renewables publishes the least green-looking number in the market, while suppliers whose green story is entirely purchased paper publish perfect scores.
Once you see it, the paradox is the single most useful diagnostic in Irish green marketing. A disclosed 100% tells you a supplier bought enough certificates. A disclosed 43.74% from a supplier that names the community wind farms it buys from tells you the number and the truth have parted company — and that you need to read the evidence, not the percentage.
What are the big brands’ green plans actually selling?
With the ladder in hand, the incumbent offers are easy to place. SSE Airtricity discloses 100% renewable across its supply; the group genuinely builds and operates wind farms on this island, which puts real hardware behind the brand, but the household badge itself is delivered by GO matching. Energia is the same shape — real Irish wind in the group, certificate matching on the bill — with one instructive wrinkle: its Republic of Ireland licence disclosed 75.48% renewable for 2024 even as its household plans are marketed as 100% renewable. A product greener than its company’s annual average is precisely the situation the CRU’s Green Source Product Verification framework exists to police, and it is why product-level claims must be independently verifiable.
Electric Ireland is the cleanest illustration of green-as-add-on: its standard supply makes no green claim and disclosed 68.5% renewable for 2024, while its dearer Green plans are backed by Guarantee of Origin certificates rather than any separate Irish supply. Bord Gáis Energy discloses 100% via certificates, subject to CRU green-source verification, and adds a claim that 10% of its gas comes from renewable sources — the only renewable-gas claim among the suppliers we track. In every case the question this page has taught you to ask is the same: not “is the claim true?” — these claims are audited — but “what exactly does the claim cover, and what did the premium fund?”
And that premium question matters, because green plans from the big brands behave like every other plan in one crucial way: they are usually 12-month discount deals with a year-2 cliff waiting at month 13. A green badge does not change the contract mechanics — the discount still dies, the standard rate still bites, and the certificates cost the supplier cents per MWh, not the euros the premium might suggest.
Does paying the green premium change anything?
The kettle test. Flick the kettle on at 7pm on a still January evening and ask: what is generating this? The answer is whatever the grid is running at that moment — and on a calm winter evening that is mostly gas, whoever you pay and whatever badge your plan carries. No tariff changes the physics. If your mental picture of a green plan is wind flowing to your kitchen, the picture is wrong on every plan sold in Ireland — the certificate system settles accounts annually, while your kettle runs on the grid instantly.
The honest version of the picture: your year’s usage was matched, megawatt-hour for megawatt-hour, by renewable generation that happened at some point, somewhere in Europe — and the strength of your plan is measured by how close “somewhere” is to an Irish community turbine.
So what does change when you pay for green? Where your money goes — which, as this page has argued from the first paragraph, is the only thing a green tariff was ever really about. Choose the strongest rung of the evidence ladder and your bill funds Irish community generation directly. Choose a certificate-matched incumbent and your bill adds a small, audited demand for European renewable certificates, plus whatever the brand invests here on its own account. Choose no badge at all and your electricity is physically identical, while your money simply buys electricity.
If your actual goal is for your consumption to line up with renewable generation in real time, the certificate system is the wrong tool altogether — that is a job for a smart time-of-use plan or a dynamic tariff, which price electricity by when the grid is cheap and clean, and for running the heavy loads when the wind is actually blowing. It is a quiet irony of the Irish market that a data-driven night-rate EV charger on a plan with no badge may track real renewable output better than any 100% green certificate plan. And whatever you choose, remember the state is already backing new renewables through the PSO levy on every bill — green plan or not, you are funding the build-out.
How do I read a green claim before paying for it?
Five questions, in order. They take ten minutes and they separate every kind of green offer on the Irish market:
- Find the disclosed fuel mix. It must be printed on the bill each year, and the annual all-island paper on semcommittee.com lists every supplier. Note the number — then remember the paradox before you judge it.
- Ask what stands behind the badge. Named Irish generators? Group-owned wind farms? Or certificates alone? The supplier’s answer places it on the evidence ladder above.
- If the plan is greener than the company, ask about verification. A green product from a supplier whose annual mix is not 100% should sit inside the CRU’s Green Source Product Verification framework — and you are entitled to request the product-level fuel mix.
- Price the premium against the plain alternative. Compare the green plan’s year-1 and year-2 cost against the cheapest comparable plan on our cheapest electricity ranking. Now you know exactly what the badge costs — pay it knowingly or not at all.
- Check the contract mechanics last. Exit fee, discount duration, month-13 rate. Green plans cliff like any other plan — the badge is not a reason to skip the year-2 check.
If that homework points you towards wanting the strongest evidence for the fewest euro, the shortlist work is already done: best green electricity ranks all nine suppliers on exactly this ladder, with verified year-1 and year-2 costs beside every badge.
