Ireland’s proposed Grid Code changes: what MPID345 could mean for data centres
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Ireland is changing how large electricity users, particularly data centres, interact with the power system.
Proposed changes to Ireland’s Grid Code would introduce new requirements for large demand facilities around Fault Ride Through (FRT), Rate of Change of Frequency (RoCoF) and Post-Fault Active Power Recovery (APR). The aim is to ensure large demand facilities remain connected during defined system disturbances and recover their electricity demand in a controlled way afterwards.
The proposal reflects a broader shift in how large electricity users are viewed by the power system. Data centres are no longer simply consumers. Their size, sensitivity to disturbances and growing correlated behaviour mean that how they respond to a fault can have implications for whole-system security.
For data centre developers and operators, this could mean greater technical complexity, new compliance requirements and changes to how projects secure power. For other countries experiencing rapid growth in data centre connections, Ireland is becoming an early test case for how grid connection requirements may evolve as data centre demand grows.
What is the Grid Code?
The Grid Code is the set of technical rules governing how users interact with Ireland’s transmission system. It sets out requirements and procedures for operating, maintaining and developing the transmission system and overseeing the actions of transmission system users.
Historically, Grid Code requirements have been closely associated with power stations and generation, particularly how generators behave during faults and changes in system conditions.
Demand users also must comply with the Grid Code, but the requirements placed on demand have generally been less onerous than those placed on generation.
There are several reasons for this:
- It is generally easier to manage an over-frequency event, when generation temporarily exceeds demand, by reducing generation. An under-frequency event, when demand exceeds generation following the loss of generation, can be more difficult to manage and may require rapid injections of active power or, in extreme cases, load shedding.
- Most individual demand connections are relatively small and uncorrelated with one another. The loss of one individual demand site therefore represents a relatively low risk to overall system security.
- Some large historical demand sites had synchronous electrical characteristics that could contribute to system stability.
Data centres are changing this picture.
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Why are data centres such a challenge for the grid?
Data centres have a distinctly different electricity demand profile from many traditional loads. Three characteristics are particularly important: scale, sensitivity and correlated behaviour.
They are very large electricity loads
Data centres can be very large loads by power system standards. In some cases, individual projects can approach the scale of the largest single infeed in a power system – the proposed 1.3 GW SINES data centre project in Portugal illustrates the scale that individual developments can reach.
This is significant because the sudden loss of a very large demand facility can itself become a serious system contingency.
Data centre demand also tends to be relatively constant. This does not mean data centres cannot be flexible. Onsite generation, battery storage and load shifting can all provide flexibility, but using these approaches to reduce electricity demand requires deliberate technical design, operational planning and contractual arrangements.
Their electricity demand is unusually sensitive to disruption
Data centres combine large electricity consumption with a particularly low tolerance for interruption.
Unlike many industrial facilities, where a short interruption may primarily mean lost production time, disruption at a data centre can affect digital services, financial transactions, communications, security systems and other services operating in the real world.
This gives data centre operators a strong incentive to protect their facilities from disturbances and maintain continuity of supply.
They can respond to disturbances in a highly correlated way
Data centres are designed to maintain very high levels of availability. When a disturbance occurs, facilities may therefore disconnect from the grid and transfer to onsite backup generation rather than risk exposing sensitive equipment to the disturbance.
For an individual site, this response can protect the facility. The challenge arises when many large data centres respond in a similar way at the same time.
Because individual facilities can be very large and their responses can be highly correlated, a relatively small system event can trigger the loss of a substantial amount of demand. That creates an operational challenge for the transmission system and can itself become a risk to whole-system security.
Data centres are a unique challenge for the grid due to the combination of scale, sensitivity to disruption and the fact that many facilities respond in similar ways.
Why is Ireland changing its Grid Code?
Ireland is particularly exposed to this issue because data centres already represent a significant share of national electricity demand, with further growth expected.
The Commission for Regulation of Utilities (CRU) reported in December 2025 that EirGrid forecast data centre electricity demand to increase from 9.4 TWh in 2025 to 14.6 TWh in 2034, increasing its share of national electricity demand from 22% in 2024 to 31% by 2034.
At the same time, EirGrid and SONI have identified a system-security risk from the collective response of data centres to faults on the transmission system. During a fault, many data centres can rapidly reduce their electricity consumption from the grid and switch to temporary backup supplies. If enough demand is lost simultaneously, the resulting imbalance can create further risks for system stability.
EirGrid and SONI's analysis found that 900 MW of demand is the maximum upper bound, or "load rejection limit", that the TSOs consider should be manageable with available operational mitigations.
This makes the behaviour of large demand facilities important to the secure operation of the Irish power system.
What is MPID345?
MPID345 is a Grid Code modification covering Fault Ride Through, Rate of Change of Frequency and Post-Fault Active Power Recovery for demand facilities.
EirGrid's recommendation is intended to introduce technical requirements for transmission-connected demand facilities, including data centres, to address the impact their response to system disturbances can have on power system security.
The proposed requirements are designed to ensure that large demand facilities do not unnecessarily disconnect during system disturbances and that, where demand does change, it recovers in a way that supports rather than undermines system stability.
Three requirements to understand
Where does MPID345 stand in 2026?
EirGrid submitted its MPID345 recommendation covering FRT, RoCoF and Post-Fault Active Power Recovery for demand facilities in April 2026. Its Grid Code modification documentation now includes the recommendation paper, a compliance and derogation framework, and separate study assessment guides for FRT, APR and RoCoF.
The CRU subsequently sought further stakeholder representations on MPID345 and its associated compliance and derogation framework between 8 and 29 July 2026. The further representations process considered EirGrid's assessment of alternative solutions, technical adviser reports, the impact of the proposals on stakeholders and changes to the proposed compliance and derogation framework.
The precise implications for individual data centres will therefore depend on the final regulatory requirements and the compliance and derogation arrangements that apply to them.
Developers and operators are already factoring MPID345 into decisions on connection design, technical assessment and compliance planning.
What does MPID345 mean for data centres?
1. New-build data centres could become more complex and costly
New data centre projects will need to consider the ability of their electrical systems to meet the emerging FRT, RoCoF and Post-Fault Active Power Recovery requirements.
This could increase development costs where additional equipment, controls or engineering work is needed to demonstrate compliance.
It could also make the operational design of a new data centre more complex, particularly where additional equipment is required to allow the facility to remain connected during faults while maintaining the facility’s resilience.
The earlier these requirements are considered in project development, the easier it should be to incorporate them into the overall electrical design rather than to retrofit solutions later.
2. Existing data centres may face new compliance requirements
The challenge is not limited to new connections.
Many existing data centres were designed and connected under requirements that did not anticipate the current scale of the system-security issue. As a result, some existing facilities may not be compliant with the emerging requirements.
The compliance and derogation framework is therefore an important part of the overall change. EirGrid has proposed a framework covering how affected demand facilities can demonstrate compliance and, where appropriate, operate under a derogation while they address any gaps.
For existing operators, understanding the technical gap between current equipment and the emerging requirements will therefore be critical.
3. Hybrid approaches to power access could become more attractive
Grid constraints are already encouraging data centre developers to explore alternative approaches to securing the power they need.
One option is to combine a smaller grid connection with onsite or private-wire generation, battery storage or other sources of flexibility.
Reducing the size of a data centre's grid connection can reduce the demand that must be served directly by the transmission system. This could make hybrid power access strategies more attractive where large grid connections are difficult to secure.
However, hybrid approaches do not remove the underlying technical and commercial challenges. Developers still need to consider reliability, planning, operating requirements, emissions, fuel availability and the economics of onsite generation and storage.
Ireland's wider connection policy is already moving in this direction. The CRU's December 2025 policy requires new data centres connecting to the electricity network to provide generation and/or storage capacity, either onsite or locally, to match their requested maximum import demand capacity.
MPID345 adds another dimension to these decisions: how the data centre behaves when a system disturbance occurs.
What can other countries learn from Ireland?
Ireland is an important test bed for this issue because data centres represent such a significant share of system demand and its power system has distinctive characteristics. Ireland’s experience also has wider international relevance.
As data centre development accelerates in other countries, large new loads can create challenges that traditional approaches to demand connections were not designed to address.
The lesson from Ireland is not necessarily that every country needs to adopt identical requirements. Instead, it is that grid connection policy needs to consider how large, concentrated demand will behave during system disturbances, not simply how much electricity it consumes under normal conditions.
This is particularly relevant to smaller power systems and constrained parts of larger systems where a single large demand connection, or the simultaneous response of several large facilities, can represent a material proportion of system demand.
The issue is already attracting attention beyond Ireland. EirGrid's April 2026 recommendation paper notes a December 2025 ENTSO-E position calling for national connection requirements to be updated to support wider European power-system stability needs.
Ireland's experience may offer a glimpse of challenges for countries and regions where data centre demand is growing.
What does this mean for the future of data centre grid connections?
The growth of data centres is changing the relationship between large electricity users and the grid.
For decades, Grid Code discussions have largely focused on how generators behave during system disturbances. More than ever, the behaviour of very large demand facilities matters too. Ireland's MPID345 process is an early example of this shift.
For data centre developers, the implications are practical. Technical requirements need to be considered earlier in project design, existing facilities may need to assess their compliance position, and hybrid approaches to securing power could become more valuable as grid constraints increase.
For system operators and policymakers elsewhere, the broader lesson is even more important. As electricity demand becomes larger, more concentrated and more sensitive to interruptions, demand itself can become a system-security consideration.
MPID345 signals a wider shift in how grids treat large loads. For data centres, securing enough power is no longer sufficient, their resilience and behaviour during grid disturbances are becoming equally important. Ireland is an early example of these requirements converging in grid connection policy.
Want to understand what these changes mean for your project or the Irish power market?
Let's talkFurther reading
For readers looking to explore the technical and regulatory changes in more detail:
- EirGrid: MPID345 Grid Code Modification Recommendation
- EirGrid: Fault Ride Through and Active Power Recovery – Plain English Overview
- EirGrid: MPID345 Compliance and Derogation Framework
- CRU: MPID345 and Compliance and Derogation Framework – further representations
- CRU: New Electricity Connection Policy for Data Centres
