RESS 6 Auctions Explained: What Irish Developers Need to Know in 2026
For Irish renewable energy developers, the main challenge with RESS 6 is no longer simply deciding how low a project can bid. A competitive offer now has to bring together project eligibility, price, supply-chain decisions, hybrid or storage configuration, grid arrangements, financing, and commitments that remain binding after an award. RESS 6 is Ireland's sixth onshore competition under the Renewable Electricity Support Scheme, administered through EirGrid's qualification and auction process. It introduces separate onshore wind and solar auction pots and ranks qualifying offers through a Composite Evaluation Score, or CES, made up of Price, Resilience and Energy System Integration scores. This means developers need to know what their project can bid, what additional CES points are commercially worth pursuing, and whether the project can deliver every commitment used to obtain those points.
The final RESS 6 Terms and Conditions were published in July 2026 and should be the starting point for any current analysis. For example, the final Renewable Capacity Factors are 35% for onshore wind and 11% for solar, while Unrealised Available Energy Compensation has been retained. Developers should therefore base qualification, bid strategy and financial modelling on the final rules rather than consultation-stage assumptions.
What Is the Renewable Electricity Support Scheme and How Does It Work?
Ireland's Renewable Electricity Support Scheme (RESS) supports qualifying renewable electricity generation through competitive auctions. The scheme forms part of Ireland's wider electricity and climate policy and is intended to promote investment in renewable generation while using competition to control the cost of support. RESS is implemented through individual competitions, each governed by its own Terms and Conditions, which means a developer cannot assume that rules from RESS 3, RESS 4 or RESS 5 automatically apply to RESS 6.
What Is RESS Designed to Support?
RESS is primarily a mechanism for bringing renewable generation onto the Irish electricity system while giving qualifying projects a defined support framework. For a developer, that support can improve revenue certainty and therefore influence investment approval, debt capacity, equity returns and the price a project can sustainably offer into an auction.
Who Is Responsible for RESS?
The Minister and Department of Climate, Energy and the Environment are responsible for RESS policy, establishing competitions and setting the Terms and Conditions. EirGrid is the Auction Administrator and administers the application, qualification and competitive bidding process.
This distinction matters because developers will deal with different bodies at different stages. EirGrid manages the operational auction process, while the scheme rules, awards and several continuing obligations sit within the wider ministerial and regulatory framework.
What Is RESS 6 and What Changed in 2026?
RESS 6 is the sixth onshore RESS competition and introduces a material change in how qualifying renewable projects compete. Price remains the largest part of auction evaluation, but it is no longer the entire story. The final framework includes technology-specific auction pots, a Composite Evaluation Score and requirements linked to the EU Net-Zero Industry Act (NZIA).
Three Changes Developers Need to Understand
The first major change is separate Onshore Wind and Solar Pots. A wind project is therefore not simply competing against every solar project on the same basis. The second is CES, which combines Price, Resilience and Energy System Integration. The third is the integration of NZIA-related requirements covering areas such as responsible business conduct, cybersecurity, data security, ability to deliver and supply-chain resilience.
These changes mean bid preparation has to start earlier than the auction submission itself. If a developer wants a Resilience Score or a higher ESI Score, those decisions may have to be reflected in equipment procurement, project design, storage sizing and contractual commitments long before construction.
RESS 5 vs RESS 6: What Has Actually Changed?
A useful way to understand RESS 6 is to separate final changes from proposals discussed during the consultation.
Area | Earlier RESS approach / RESS 5 context | RESS 6 |
Auction structure | Broader competition structure | Separate Onshore Wind and Solar Pots |
Evaluation | Strongly price-led | Composite Evaluation Score |
Price contribution | Main competitive driver | Maximum 0.85 |
Resilience | Not a central scoring component | 0 or 0.05 |
Energy System Integration | Not scored in the same form | Up to 0.10 |
NZIA requirements | Not integrated in the same manner | Directly relevant |
Solar RCF | 11% | 11% |
Onshore wind RCF | 35% | 35% |
Minimum Total Offer Quantity | Previous rules differed | 1 MW |
Eligible technology set | Broader in previous competitions | Wind, solar and specified hybrid configurations |
The important editorial point is that consultation proposals are not final rules. For example, proposed higher capacity factors discussed earlier in 2026 were not adopted: the final RESS 6 Terms and Conditions use 35% for onshore wind and 11% for solar.
What Are the Key RESS 6 Dates and Deadlines?
RESS 6 follows a staged process covering qualification, review, auction submission and award. Missing an early qualification or financial-security date can prevent a project from reaching the auction itself, so development teams should manage the timetable as part of the project programme rather than treating November as the only important period.
Stage | RESS 6 date |
Qualification Application opens | 30 July 2026, 10:00 |
Qualification Application closes | 27 August 2026, 17:00 |
Bid Bond Posting Date | 28 August 2026 |
Provisional Qualification Decision | 25 September 2026 |
Final Application Withdrawal Date | 29 September 2026, 17:00 |
Final Qualification Decisions | 21 October 2026 |
Auction Information Pack | 22 October 2026 |
Resilience Declaration window | 23–27 October 2026 |
Financial Questionnaire opens | 28 October 2026 |
Financial Questionnaire closes | 29 October 2026, 10:00 |
Auction Submission opens | 29 October 2026, 12:00 |
Auction Submission closes | 5 November 2026, 12:00 |
Provisional Auction Results | 18 November 2026 |
Final Auction Results | 2 December 2026 |
Notice of Award | 10 December 2026 |
These dates come from EirGrid's final RESS 6 Auction Timetable published on 16 July 2026.
Which Projects Can Qualify for RESS 6?
RESS 6 eligibility has two layers. First, the project's technology or combination of technologies must fall within an Eligible Technology category. Second, the individual project must satisfy requirements relating to matters such as planning, grid arrangements, offer quantity, declarations, financial security and ability to deliver. A project being “solar” or “wind” is therefore not sufficient by itself.
Eligible Renewable Technologies
The final Terms and Conditions identify six technology categories:
Onshore Wind
Solar
Hybrid Wind and Solar
Hybrid Wind and Storage
Hybrid Solar and Storage
Hybrid Wind and Solar and Storage
These categories show that RESS 6 explicitly recognises hybrid configurations while keeping renewable generation centred on onshore wind and solar PV. Storage has an important role, but storage output itself does not receive RESS 6 support. The Terms and Conditions state that support is calculated for the Primary Technology and, where applicable, Secondary Technology, and is not payable for storage output.
Technologies Outside the RESS 6 Scope
Technologies that appeared within broader previous RESS eligibility, such as hydro, biomass, biogas and qualifying waste-based high-efficiency CHP, are not listed among the final RESS 6 Eligible Technologies. The 2026 auction is therefore much more clearly centred on onshore wind, solar and their specified hybrid/storage combinations.
Planning Permission Requirements
A RESS 6 project must have a full and final grant of planning permission for the project described in its Application for Qualification. A notification that a decision to grant planning permission has been made is not enough. The planning permission also has to provide sufficient development life for the project to be constructed and reach Commercial Operation by the relevant Longstop Date.
For developers, this means the RESS application needs to match the development that can actually be built under the planning consent. Material assumptions about installed capacity, technology mix and layout should therefore be checked against planning before they are used in the auction model.
Grid Connection Requirements
RESS 6 also requires the project to be a Grid Contracted Project. The final Terms and Conditions define this through qualifying Grid Connection Arrangements with the TSO or DSO and require those arrangements to permit export of at least the project's Total Offer Quantity.
Grid eligibility should therefore be tested at the same time as the commercial model. A project cannot sensibly optimise an Offer Price around generation that its grid arrangement does not permit it to export.
Minimum Project and Offer Requirements
The Minimum Total Offer Quantity is 1 MW. The maximum is linked to the MW equivalent of 600 GWh per year using the Deemed Energy Quantity methodology. Smaller projects can be aggregated only where they are structured as one project behind a single meter and under a single applicant entity that satisfies the qualification rules.
Total Offer Quantity includes the Primary Technology Offer Quantity and, where applicable, the Secondary Technology Offer Quantity. It excludes Electricity Storage Capacity. This distinction becomes important when developers compare renewable MW, storage MW/MWh, grid capacity and CES scoring.
Qualification Documentation and Bid Bond
The qualification process requires an Application for Qualification, the relevant declarations and financial security. The Bid Bond is calculated at €6/MWh multiplied by annual Deemed Energy Quantity, which itself uses Total Offer Quantity, 8,760 hours and the relevant Renewable Capacity Factor.
For example, the final Terms and Conditions use a 35% RCF for onshore wind and 11% for solar. Hybrid wind-solar projects use a weighted RCF based on their wind and solar offer quantities.
How Do the RESS 6 Auction Pots and Hybrid Project Rules Work?
RESS 6 contains two technology-specific pots: the Onshore Wind Pot and the Solar Pot. This matters because CES ranking and the relevant Maximum Offer Price Considered operate within the appropriate technology pot, so a project's competitive context begins with its Primary Technology.
Onshore Wind Auction Pot
Standalone onshore wind projects and Hybrid Wind and Storage projects are allocated to the Onshore Wind Pot. Wind-solar hybrids also enter the Onshore Wind Pot where wind is the project's Primary Technology.
For a wind developer, procurement decisions around turbines, drivetrains and permanent magnets can therefore affect resilience scoring, while storage or a secondary solar component may affect Energy System Integration scoring.
Solar Auction Pot
Standalone solar projects and Hybrid Solar and Storage projects are allocated to the Solar Pot. A wind-solar hybrid enters this pot where solar is the Primary Technology. This separation recognises that wind and solar projects have different cost profiles, equipment supply chains, generation patterns and development economics. Developers can therefore evaluate competitors within a more technology-specific framework.
How Wind-Solar Hybrid Projects Are Assigned
Where both wind and solar form part of a RESS 6 project, the Primary Technology is the technology with the greater MW capacity, while the lower-capacity renewable technology is treated as the Secondary Technology. The Primary Technology then determines which auction pot the project enters. That means technology sizing can affect both project economics and auction classification. The decision should therefore be made from an integrated technical and financial model rather than by maximising a scoring component in isolation.
How Does the RESS 6 Composite Evaluation Score Work?
The Composite Evaluation Score is the central change in RESS 6 auction evaluation. Eligible offers are ranked using the sum of three components: Price Score, Resilience Score and Energy System Integration Score. CES ranges from 0 to 1.00 and is used for winner selection.
CES component | Maximum score | Main commercial question |
Price Score | 0.85 | What is the lowest sustainable Offer Price? |
Resilience Score | 0.05 | Is the procurement route worth the scoring benefit and deliverable? |
Energy System Integration Score | 0.10 | Do secondary technology and storage improve total project economics as well as CES? |
Maximum CES | 1.00 | Which configuration gives the strongest deliverable bid? |
A strong CES does not automatically mean a strong investment. The useful development question is whether the same assumptions that improve CES also leave the project financeable and deliverable.
How the Price Score Works
Each qualifying Offer can receive a Price Score of up to 0.85. The formula uses the project's Bid Price, the Maximum Offer Price Considered for the relevant Technology Pot and an auction exponent known as k, which is to be published before the Final Application Withdrawal Date.
Price therefore remains the largest part of CES, but setting an Offer Price should start with project economics rather than the scoring formula. Developers need a financial model that captures realistic CAPEX, OPEX, construction timing, financing costs, generation, degradation where relevant, grid exposure, RESS revenues, Community Benefit Fund costs, tax and a suitable contingency. An artificially low price may improve the Price Score while leaving too little return or contingency to absorb cost increases.
How the Energy System Integration Score Works
The Energy System Integration Score can reach 0.10 and is calculated as:
Energy System Integration Score = Secondary Technology Score + Storage Score.
For a wind-solar hybrid, the Secondary Technology contribution rises as the Secondary Technology becomes a larger share of Total Offer Quantity.
Secondary Technology share | Secondary Technology Score |
0% to <10% | 0 |
≥10% to <20% | 0.0063 |
≥20% to <30% | 0.0125 |
≥30% to <40% | 0.0188 |
≥40% to <49.99% | 0.0250 |
The maximum Secondary Technology Score is therefore 0.025, leaving storage capable of contributing the larger part of the ESI opportunity.
How the Storage Score Works
To receive a Storage Score, the project's Electricity Storage Capacity in MWh must be at least equal to its Total Offer Quantity in MW. A 10 MW Total Offer Quantity would therefore require at least 10 MWh of storage capacity before a Storage Score can be calculated.
Electricity Storage Duration | Storage Score |
≥0 to <2 hours | 0 |
≥2 to <4 hours | 0.015 |
≥4 to <6 hours | 0.030 |
≥6 to <8 hours | 0.045 |
8 hours | 0.060 |
>8 hours | 0.075 |
Longer qualifying duration can improve CES, but storage should not be added simply to chase a score. Additional duration means additional capital, operating assumptions, degradation exposure, augmentation or replacement requirements and financing needs.
Why CES Commitments Must Be Tested Before Bidding
Any representation or commitment that gives a successful applicant a Resilience Score or an ESI Score greater than zero becomes binding under the final Terms and Conditions. Failure to fulfil it constitutes a breach
This is also where experienced financial modelling and commercial advisory can add value. Stakelum Consultancy supports renewable projects through project evaluation, financial modelling and bid-related commercial work, allowing developers to test how scoring decisions affect project returns before committing to an auction configuration.
How Does RESS 6 Affect Project Revenue and Financial Modelling?
A RESS 6 financial model needs to connect auction support with actual project generation and market exposure. Modelling the Offer Price as a simple fixed revenue line can miss material features such as the Market Reference Price, Difference Payments, indexation, dispatch-down treatment, UAEC, capacity-market adjustments, Community Benefit Fund contributions and restrictions on Guarantees of Origin.
Offer Price, Strike Price and Support Revenue
The Offer Price is the €/MWh price submitted into the auction. For a successful project, it forms the basis of the Strike Price, subject to the relevant indexation provisions. The support mechanism then compares the applicable Strike Price with the Market Reference Price for settlement purposes.
Commercially, this means a developer should model the bid from both directions: what price is competitive enough to produce an acceptable Price Score, and what price leaves sufficient project return after construction, financing and operating risk.
How the Market Reference Price Works
The final Terms and Conditions state that the hourly Day-Ahead Market price is the Market Reference Price for settling the FIP, while also recording that this treatment may change depending on the State aid approval process. Any change is to be confirmed to applicants before the Final Application Withdrawal Date.
How the Two-Way Revenue Mechanism Works
For qualifying hours where the Market Reference Price is below the Strike Price and the scheme conditions are satisfied, the Support Payment is based on the difference multiplied by the relevant loss-adjusted RESS metered quantity. Where the Market Reference Price exceeds the Strike Price, a Difference Payment applies in the opposite direction.
A simplified illustration is useful. If a project's Strike Price were €90/MWh and the relevant Market Reference Price were €70/MWh, the gap would be €20/MWh before applying the full scheme calculation and conditions. If the reference price were €110/MWh, the same €20/MWh gap would move in the opposite direction through the Difference Payment mechanism.
How Long Does RESS 6 Support Last?
RESS 6 should not be described simply as a fixed 15-year contract. Under the final Terms and Conditions, the Support End Date is the earliest of the relevant termination/revocation events, 4 March 2046 subject to permitted extensions, or 16.5 years after the RESS 6 Support Start Date.
What Is Unrealised Available Energy Compensation?
Unrealised Available Energy Compensation (UAEC) is an availability-related part of RESS 6 support. It compensates qualifying unavailable generation at the Strike Price where availability is not converted into generation because of curtailment or oversupply. Importantly, the final Terms and Conditions state that UAEC does not compensate transmission constraints, because constraints are retained as a locational signal.
That distinction is important. “Dispatch down” is often used broadly in industry discussion, but a financial model should separate curtailment, oversupply, and constraint exposure according to the actual RESS rules rather than applying a single compensation assumption to all lost generation.
Why UAEC Matters to Project Economics
Dispatch-down assumptions can materially affect renewable project revenues, particularly as renewable penetration increases. UAEC reduces some exposure by compensating qualifying unrealised generation, but it does not remove every grid-related risk. The final formula also subtracts other compensation received for the same Unrealised Available Energy.
What NZIA, Supply-Chain and Cybersecurity Requirements Must Developers Consider?
RESS 6 incorporates requirements connected with Article 26 of the EU Net-Zero Industry Act. The EU framework requires renewable-energy auctions within its scope to address areas including responsible business conduct, cybersecurity and data security, ability to deliver and sustainability or resilience contributions. RESS 6 implements these concepts through qualification requirements, enduring obligations and auction scoring.
What Financial Security and Delivery Commitments Follow a RESS 6 Bid?
Participation carries financial commitments before and after the auction. These requirements are intended to support project deliverability and reduce the risk that successful capacity fails to reach operation.
Bid Bond Requirements
The Bid Bond Required Amount is:
€6/MWh × Deemed Energy Quantity
where Deemed Energy Quantity is derived from Total Offer Quantity × 8,760 hours × the relevant Renewable Capacity Factor. That cost should be incorporated into bid preparation and liquidity planning, particularly across a portfolio of projects rather than considered only at individual SPV level.
Renewable Capacity Factors Used in RESS 6
The final RESS 6 reference factors are:
Eligible Technology | Renewable Capacity Factor |
Onshore Wind | 35% |
Solar | 11% |
Hybrid Wind and Storage | 35% |
Hybrid Solar and Storage | 11% |
Wind and Solar hybrids | Weighted using wind and solar Offer Quantities |
These are final RESS 6 values. Developers should avoid the 45% wind and 14% solar figures found in some consultation-stage material.
How Should Irish Developers Prepare for the RESS 6 Auction?
RESS 6 preparation should bring technical, commercial, financing, procurement and compliance decisions into one process. The most common strategic error would be to optimise one variable, usually Offer Price or CES, without checking the effect on the rest of the project.
Step 1: Confirm Eligibility Before Optimising the Bid
Start with the project's technology category, final planning permission, grid arrangement, Total Offer Quantity and required declarations. There is little value in refining price sensitivities for a project that has an unresolved qualification problem.
Step 2: Determine the Correct Auction Pot
Confirm Primary and Secondary Technology before building competitor or pricing assumptions. For wind-solar hybrids, the greater MW capacity determines Primary Technology and therefore the relevant pot.
Step 3: Build the Base Financial Model
The base model should establish the project's economics before optional CES decisions are added. At minimum, it should test construction cost, OPEX, generation, financing, market prices, RESS settlement, UAEC, Community Benefit Fund costs, degradation where applicable, tax, delays and downside cases.
Stakelum Consultancy provides financial modelling and initial project evaluation services into the RESS process. A developer needs to know the project's sustainable price range before deciding how aggressively to bid.
Step 4: Model CES Before Finalising the Offer Price
Once the base economics are understood, add the Price Score formula, possible Resilience Score and available ESI combinations. Model several realistic project configurations rather than a single case.
A useful comparison might include:
Scenario | Price strategy | Resilience | Secondary technology | Storage | Commercial purpose |
Base case | Bankable price | No score | None | None | Establish minimum viable project |
Resilience case | Same/base-adjusted | 0.05 | None | None | Test procurement premium |
Hybrid case | Adjusted | As applicable | Included | None | Test Secondary Technology value |
Storage case | Adjusted | As applicable | As applicable | Included | Test ESI vs storage cost |
Combined case | Adjusted | 0.05 | Included | Included | Test maximum practical CES |
The objective is to find the best commercial bid, not simply the highest theoretical score.
Step 5: Test the Economics of the Resilience Score
Compare the 0.05 potential benefit with changes in equipment price, supplier choice, delivery timing, documentation requirements, foreign-exchange exposure and financing. If a resilience-compliant package materially raises CAPEX, the project may need a higher Offer Price, which can reduce its Price Score. That relationship, procurement cost versus Resilience Score versus Price Score, is one of the most important commercial tests in RESS 6.
Step 6: Test Storage and Hybridisation Commercially
Storage can contribute as much as 0.075 to the ESI Score, while Secondary Technology can contribute up to 0.025. That makes system integration potentially significant to ranking. But an eight-hour or longer battery is a major project decision, not a free scoring feature. Model battery CAPEX, usable capacity, efficiency, degradation, augmentation, operating strategy and replacement requirements alongside the CES benefit. CES should never be optimised independently of project return, financing and deliverability.
Step 7: Lock Down Supplier and Compliance Evidence
Before making resilience or cybersecurity commitments, confirm whether suppliers can provide the evidence that will later be needed. Equipment origin, assembly, OEM documentation, ICT supplier arrangements, operational control, and data handling should be covered before contracts become difficult or expensive to change.
Step 8: Stress-Test Downside Scenarios
A serious RESS model should test at least:
construction-cost increases;
financing-rate increases;
project delay;
generation underperformance;
curtailment;
transmission constraints;
supplier delay;
storage degradation;
loss of a planned CES benefit;
compliance or milestone delay.
The key question is whether the project remains financeable and attractive if more than one downside occurs at the same time.
Step 9: Confirm That Every Auction Commitment Can Be Delivered
Before submission, the development team should ask one final question: If this project wins using the assumptions in the bid, can we finance, procure, construct and operate that same project within the RESS requirements? That is where commercial judgement matters. Stakelum Consultancy's commercial advisory, financial modelling and bid management capabilities can support developers in assessing the relationship between auction competitiveness and the long-term economics of the project.
Final Takeaway for Irish Renewable Energy Developers
RESS 6 changes the commercial question from “How low can this project bid?” to “What configuration and Offer Price produce the strongest deliverable project?” Price still carries most of the Composite Evaluation Score, but supply-chain resilience, secondary renewable technology, battery storage, cybersecurity, grid position and post-award commitments can now influence both auction ranking and project cost. Developers therefore need to evaluate CES and project economics together, using the final 2026 rules rather than assumptions from earlier consultation material.
For developers preparing or reviewing a RESS 6 project, Stakelum Consultancy can support initial project evaluation, financial modelling, commercial advisory and bid management. The value of that work is in testing the assumptions before they become auction commitments, so that a competitive RESS bid still makes commercial sense if it wins.
