The Renewable Electricity Support Scheme (RESS) is Ireland’s main support scheme for onshore wind and solar, a sealed-bid auction for two-way contracts for difference run by state grid operator EirGrid. It is the key route to the government’s 2030 targets of 8 GW of solar and 9 GW of onshore wind, and in recent rounds solar has won far more than wind, with 960 MW in RESS 4 and around 860 MW in RESS 5.
The sixth round is the biggest redesign since the scheme began in 2020, with new rules on how bids are scored, what they compete against and what winners have to deliver.
RESS 6 at a glance
Bidding for this year’s auction opens on 29 October and closes a week later, on 5 November. Developers find out where they stand on 18 November, when the provisional results come out, and the final list is published on 2 December. Winners can look forward to a fixed price for every MWh they produce, adjusted each year for inflation, for up to 16.5 years – a little shorter than the 20 years common in Germany and the UK. Price still counts for most of the score, at 85 percent, with up to 15 percent available for using equipment from outside China and adding storage or a second technology. But before any of this is final, the European Commission still has to approve it under EU state aid rules.
How the contract works
A two-way contract for difference sets a fixed price, known as the “strike price”, for every MWh a project produces. When the wholesale price is lower, the project receives the difference. When it is higher, the project pays the difference back. Developers get stable revenue, while consumers are protected from overpaying when markets are high. The strike price is simply what the project bid in the auction, so a lower bid means less support.
Solar in a pot of its own
To date, solar and onshore wind have competed in a single auction, mostly on price. From this round, they will be competing in two separate pots. Solar bids only against solar, and the government sets a minimum and maximum volume for each pot.
The idea is to stop one technology from crowding out the other, and to apply EU rules that differ by technology. For solar developers, it means the competition has shifted away from wind towards other solar farms, which matters, since wind has tended to come in cheaper. In RESS 5, solar averaged €100.63/MWh and wind €96.56/MWh.
How bids are scored
Every bid gets a score out of 100. Price is worth up to 85, so the cheaper the bid, the higher it scores. The remaining 15 come from two new criteria under the EU’s Net-Zero Industry Act (NZIA): 5 for a resilient supply chain and up to 10 for helping the grid, mostly by adding storage. The highest scores win, until the pot is full.
Price still settles most contests, so a cheap bid with no extras can easily beat a pricier one that meets all the new criteria. Where the new criteria count is in a close race, where only a few marks separate the bids.
The China question
The resilience points are all or nothing, and for solar they depend on where the equipment comes from. To get them, a project has to use modules that are not assembled in China, inverters and cells that are not made in China, and at least four main components from outside China.
China dominates almost every stage of solar manufacturing, so few projects will meet that bar without paying more for equipment. The government knows this and has asked bidders to give their project costs both with and without the resilience criteria. Any project that claims the points and wins will later have to prove its supply chain with customs and manufacturer documents. If it can’t, it risks losing part of its performance bond, the security deposit every winner has to put up.
Points for batteries
Storage is worth up to 7.5 of the 100 marks, but only if the battery is big enough. Its capacity in MWh has to be at least equal to the project’s generating capacity in MW, so a 10 MW solar farm needs a battery of at least 10 MWh before it scores anything.
Above that minimum, the score depends on how long the battery can keep delivering power:
– under 2 hours: no marks
– 2 to 4 hours: 1.5 marks
– 4 to 6 hours: 3 marks
– 6 to 8 hours: 4.5 marks
– 8 hours: 6 marks
– more than 8 hours: 7.5 marks
Most batteries being built today run for 1 to 2 hours, so longer storage clearly scores better. Solar and wind hybrids can add another 2.5 marks. The battery is not paid under RESS, but it can still earn its own income in the wholesale and balancing markets.
No way back
Once a winner signs its contract, it cannot pull out, not even partly. The project then has ten milestones to meet, from getting its grid connection to starting commercial operation. If it misses an interim deadline, the government can draw on up to 25 percent of its performance bond, and if it misses a final deadline, the contract can be cancelled. Whatever was promised at bid stage, including the battery and where the equipment comes from, becomes binding.
What stays the same
Some things have not changed. Projects still need full planning permission and a grid connection agreement before they can bid. If a project has to switch off because there is too much power on the system, it is still paid at the strike price, though not if the cause is a local grid bottleneck. Every project pays at least €2/MWh into a community benefit fund. And for solar, the scheme still assumes the panels produce on average 11 percent of their maximum output over a year.
The view from central Europe
Every EU country has to apply the NZIA’s non-price criteria, the scoring rules that go beyond price, to at least 30 percent of the volume it auctions each year, or to 6 GW a year. Ireland is applying them to its entire auction, which is more than the EU requires.
Approaches differ across the EU. Austria, for example, uses a “Made in Europe” bonus on its investment grants for smaller solar and battery systems, which in this year’s funding rounds raises the grant by 10 percent when European components are used. In Germany, industry groups have warned against complex rules and extra paperwork, and the cost to consumers is still under discussion. The Centre for European Policy has estimated that resilience criteria in Germany’s tenders for ground-mounted solar could cost €38 million to €60 million a year.
Ireland is among the first countries to try these rules in a real solar auction, so its results will be watched well beyond Ireland.
What to watch
– How many solar bids claim the resilience points, and how many of them win
– Whether the average solar price rises above RESS 5’s €100.60/MWh
– How many winning projects include storage, and how long their batteries can run
– Whether solar fills the full volume of its pot
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