Grid congestion: when may a grid operator refuse transport?

Grid congestion (netcongestie) does not give a Dutch grid operator a free hand to refuse transport. Under the Energy Act (Energiewet), in force since 1 January 2026, a grid operator (netbeheerder) may only refuse if it can show with data that the physical capacity is insufficient and that congestion management cannot solve the problem; the main exception is the priority framework, which lawfully lets certain categories of projects move ahead in the queue.

A refusal must be reasoned, capacity must be allocated without discrimination, and if you are refused you can take the dispute to the Netherlands Authority for Consumers and Markets (Autoriteit Consument & Markt, ACM) or to the civil court.

Which rules apply to grid congestion since 1 January 2026?

Since 1 January 2026 the Energy Act applies, and it replaced both the Electricity Act 1998 (Elektriciteitswet 1998) and the Gas Act (Gaswet). The core duties of grid operators are the same in substance; what changed is the wording, the numbering and the technical codes underneath.

The second layer, the technical codes, matters more than it sounds. For years the congestion management rules sat in chapter 9 of the old electricity grid code (Netcode elektriciteit), which practitioners cited by heart. In February 2026 the ACM adopted a new set of codes under the Energy Act, published in the Government Gazette (Staatscourant) on 20 February 2026. They include the Systeemcode elektriciteit 2026, which took over the rules of the old grid codes. Article references to the old codes, and to chapter 9 in particular, no longer point anywhere. If you rely on a template objection or an advice memo written before 2026, check the citations before you send it.

Above both sits the case law. Decisions of the ACM in dispute procedures, judgments of the civil courts and rulings of the Trade and Industry Appeals Tribunal (College van Beroep voor het bedrijfsleven, CBb) built the practical standard for what a grid operator must prove. That body of case law was decided largely under the old Electricity Act. It remains relevant, because its principles, the duty to transport, the duty to give reasons and the prohibition of discrimination, were carried over into the Energy Act.

What is the difference between physical and contractual congestion?

Contractual congestion means the capacity is fully booked on paper; physical congestion means the network components actually reach their limits. The distinction is the basis of most successful challenges to a refusal.

Contractual congestion means that the sum of the transport rights already granted exceeds the technical capacity of a cable or transformer. It says nothing about what actually flows through that cable. Solar parks produce nothing at night, wind farms produce nothing in still weather, and industrial connections rarely draw their contracted maximum for more than a few hours a year. A grid operator that refuses transport only because its books are full, while the component is demonstrably not loaded to its limit in the relevant hours, has not yet shown a sufficient ground for refusal.

Physical congestion means that the thermal or voltage limits of the components are actually reached, or would be reached if the new request were granted. That can be a valid ground for refusal. But it is a factual claim and it must be evidenced: measured loads, the capacity of the specific substation and cable, and the periods in which the limit is reached. The burden of substantiating this rests on the grid operator. A general reference to a congestion map does not discharge it.

Between the two lies the question that decides most cases. Even where physical congestion exists, the grid operator must first examine whether congestion management can create room. Only if that examination shows that it cannot, may transport be refused.

What must a grid operator do before it refuses transport?

A refusal is the end of a sequence of steps, not the starting point. The grid operator must establish the physical constraint, investigate whether congestion management can create room, and apply it where it can.

In practice this means the grid operator must determine whether the constraint is physical, carry out a congestion investigation (congestieonderzoek) for the area concerned, publish the outcome, and determine whether enough flexibility can be contracted from connected parties to accommodate the request. Where flexibility is available, congestion management must be applied. The grid operator has no discretion to prefer refusal simply because managing the constraint is more work.

The refusal itself must be reasoned. In practice that means naming the substation and the component that is constrained, giving the load data on which the conclusion rests, stating what the congestion investigation found and why flexibility is insufficient, and explaining where you stand in the queue. A generic letter stating that “the region is congested” gives you nothing to test and is open to challenge. When you receive such a letter, ask for the underlying data in writing. Your request itself creates the record on which a later dispute will be decided.

There is a second, quieter obligation: transparency about the queue. A grid operator must be able to show where you stand, on which date your request was registered as complete, and what happened to requests registered later. Without that, the non-discrimination requirement cannot be tested. If the grid operator cannot produce this information, that is itself a weakness in its position.

How does the queue work, and who gets priority?

Capacity is in principle allocated in order of application: first come, first served. Since 1 January 2026, a priority framework of the ACM allows grid operators to give precedence to three defined categories of projects.

First come, first served is not an administrative convenience. It is the default expression of the duty not to discriminate. A grid operator that lets a later applicant through while an earlier one waits must be able to justify that on objective grounds.

The priority framework has a legal basis. The CBb confirmed that the ACM is competent to adopt such a framework, but required it to substantiate better which parties get priority. The ACM then adopted a new framework (Codebesluit prioriteringsruimte transportverzoeken 2025) on 12 December 2025, which has applied since 1 January 2026; for housing connections the previous working method continues until 1 July 2026. It allows grid operators to give precedence to:

• congestion relievers: projects that themselves create room on the grid;
• safety: connections for, for example, hospitals, emergency services, police and defence;
• basic needs: connections for societal needs such as housing, education and public transport.

Everything outside those categories stays in the ordinary queue. For a producer this cuts both ways. If your project falls within a priority category, you have to claim and substantiate this rather than assume it. If it does not, the framework is a lawful reason for others to move ahead of you, but only within its boundaries. Priority granted outside the framework, or without a recorded justification, is exactly the kind of deviation that makes a refusal open to challenge.

How does congestion management work, and what are you paid?

Congestion management means the grid operator contracts flexibility from connected parties, so that it can allocate more capacity than the physical peak would allow. You are paid for that flexibility, either at a price you bid yourself or, where participation is compulsory, at a regulated price.

Two families of products do the work. In redispatch, the grid operator asks a party to increase or reduce its feed-in or offtake at a given moment, against payment. In a capacity limitation contract (capaciteitsbeperkingscontract), the party accepts in advance, against a fee, that its feed-in or offtake will be capped during defined congestion periods. On top of that, grid operators offer alternative transport rights, such as time-bound transport rights and fully variable transport rights, which give access during part of the hours or whenever capacity is available.

Participation is not purely voluntary. According to the ACM’s overview of congestion measures, connected parties with more than 60 MW of contracted capacity must take part in resolving congestion, and in a designated congestion area the operator may also require parties above a threshold it sets between 1 MW and 60 MW to offer their flexibility (Article 9.1 Netcode elektriciteit). That obligation gives the mechanism enough liquidity to function.

The price depends on the route. In market-based congestion management you set your own bid. Where the grid operator applies congestion management on the basis of the participation obligation, you receive a price that may not exceed what is customary in normal economic transactions. That formula protects the grid operator against opportunistic pricing. It also protects you, because a payment that ignores the actual loss you suffer is equally out of line with normal economic transactions.

Your loss is not only the value of the electricity you did not deliver. Where output is curtailed, the missed subsidy revenue under a scheme such as the SDE++ and the consequences under an existing power purchase agreement, including any obligation to deliver a contracted volume, form part of your real opportunity cost. Those elements belong in the negotiation and, if it comes to that, in the evidence. There is no published tariff for flexibility. Whether a price is in line with the market is assessed afterwards, against comparable transactions and the underlying costs. That makes contemporaneous records of your own costs unusually valuable.

The room to negotiate the rest of the contract is limited. The definition of the product, the technical requirements, the response times and the settlement rules come from the codes. Terms that deviate from them, or that treat one grid user differently from another, are not enforceable. What you can genuinely negotiate is the volume, the duration, the availability windows and, where the regulated price rule applies, the price within that ceiling.

Which remedies do you have: the ACM or the civil court?

You can submit a dispute with a grid operator to the ACM, which gives a binding decision, or go to the civil court. The two routes can be used in parallel.

The first route is the dispute procedure at the ACM. Under Article 5.4 of the Energy Act, you can submit a dispute with a grid operator about the way it applies the statutory rules and the codes to the ACM. According to the ACM, it takes a decision within two months of receiving the complaint, and it can extend that period by two months if it needs more information. The advantage is that a regulator with technical expertise tests the load data and the congestion investigation, and the costs are modest compared with litigation. You can appeal an ACM decision to the CBb, where you can also ask for interim relief if the matter cannot wait.

The second route is the civil court, which is the route where speed or money is the issue. Summary proceedings (kort geding) are appropriate where a decision cannot wait, for example because a subsidy deadline or a contractual delivery date will be missed while the case is investigated. The claim is then for an order that the grid operator make an offer for transport. Proceedings on the merits are the place for damages and declaratory relief. Note that a grid operator acts as a company when it deals with connection and transport requests. Its refusal is in principle not an administrative decision, so damages are claimed from it under civil law, not under the General Administrative Law Act (Algemene wet bestuursrecht).

Which route fits depends on what you actually need. If your objective is access, the ACM route is usually stronger, because the regulator can order the grid operator to make an offer and is equipped to test the technical justification. If your objective is compensation for a project that has already been delayed, the civil court is the forum. A claim in tort under Article 6:162 of the Dutch Civil Code (Burgerlijk Wetboek, BW) requires you to prove the unlawful act, the loss, and the causal link between them.

How do you prove your loss?

The recoverable loss is usually not the hardest question; proof is. Almost all of the relevant evidence sits with the grid operator, so ask for the data at the moment of the refusal and build your own loss file at the same time.

A refusal that turns out to be unlawful can cause lost margin on electricity not delivered, forfeited subsidy revenue, penalties or lost value under an offtake agreement, financing costs on an asset that stands idle, and the cost of a delayed project as a whole. All of that is in principle recoverable if you can establish the unlawfulness and the causal link.

The difficulty is that the load measurements, the congestion investigation, the queue administration and the decisions on other applications in the same area are all in the hands of the grid operator. That imbalance is why the transparency and reasoning duties matter so much in practice. Ask for the data in writing when you receive the refusal, and keep the answer. If the grid operator refuses or answers vaguely, that refusal becomes part of your case. In civil proceedings, the court can also order a party to provide copies of specific documents relevant to the dispute. Since 1 January 2025 this right of access to evidence is laid down in Article 194 of the Dutch Code of Civil Procedure (Wetboek van Burgerlijke Rechtsvordering, Rv).

Build your loss file at the same time, not afterwards. Contemporaneous records of production forecasts, subsidy entitlements, contractual commitments and financing costs are far more persuasive than a reconstruction made two years later by an expert.

What should you check as a producer or developer?

Your legal position is largely fixed before any dispute arises: the date on which your request is registered as complete fixes your queue position. Check at least the following:

• That your transport request is complete, and the date the grid operator registered it as complete.
• Which substation or component the refusal names, and the load data behind it.
• What the congestion investigation showed, and why flexibility was found insufficient.
• Your queue position, and whether later applicants were let through.
• Whether your project falls within one of the three priority categories, and if so, claim it explicitly.
• Whether a capacity limitation contract, a time-bound transport right or storage on site gets you connected sooner.

What should you check as a party offering flexibility?

If your connection is above the threshold the operator has set for a congestion area (at least 1 MW), you must offer your available flexibility. Before you sign, check:

• Whether participation is market-based (your own bid) or compulsory (regulated price).
• That the price covers your real opportunity cost, including SDE++ revenue and PPA volume commitments.
• The volume, duration and availability windows, which are the terms you can negotiate.
• That the product terms match the codes, since deviating terms are not enforceable.
• That you keep contemporaneous records of production forecasts and costs for a later price dispute.

What can we do for you with grid congestion?

Our energy law practice assists producers, developers and industrial grid users. In practice we:

• Request the load data, congestion investigation and queue information from the grid operator in writing after a refusal.
• Test the refusal against the Energy Act, the Systeemcode elektriciteit 2026 and the ACM priority framework.
• Prepare and conduct a dispute with the ACM under Article 5.4 Energy Act, and any appeal to the CBb.
• Start summary proceedings (kort geding) for an order to make a transport offer when a subsidy or delivery deadline is at stake.
• Review and negotiate capacity limitation and redispatch contracts, including the price.
• Build your loss file and bring a damages claim under Article 6:162 BW.

Summary

• Since 1 January 2026 the Energy Act and the new codes, including the Systeemcode elektriciteit 2026, apply; old Netcode references are outdated.
• A grid operator may only refuse transport if it shows physical congestion with data and shows that congestion management cannot create room.
• Capacity is allocated first come, first served, except for the three categories in the ACM’s priority framework.
• Parties above the operator’s threshold (at least 1 MW) in a congestion area must offer flexibility; under that obligation the price may not exceed what is customary in normal economic transactions.
• You can submit a dispute to the ACM (decision within two months, extendable by two) or go to the civil court for access or damages.

Frequently asked questions