Netcongestie and the 2028 kWmax: the connection, not the peak

Netcongestie in numbers

• At the end of June 2026 the regional grid operators' waiting lists held 15,498 requests for more offtake capacity (9,986 MW) and 8,558 for feed-in (5,693 MW), both up in MW since the end of 2025; TenneT's own list comes on top (Solar Magazine, 6 Oct 2026).
• A 2025 market study for Energy Storage NL put the number of companies on a waiting list for a connection above 20,000 in 2024, and counted 312 flexible grid contracts signed that year (Energy Storage NL & Ecorys).
• Liander's 2026 tariff sheet states that an increase in contracted capacity cannot be granted where the grid lacks capacity (Liander 2026).

For a business that wants to add EV chargers, a heat pump or a production line, that turns the battery question around: not "how much does it save?" but "does it let us grow at all?"

What a kW of peak is worth in 2026

A large Dutch connection pays per contracted kW, per kW of the month's highest quarter-hour (kWmax) and per kWh. The kW charges per year, for one kW held down every month (and, in the last column, also taken off the contract):

The kWmax is the highest load per clock quarter-hour of the month (Stedin regulation 2024), so one missed quarter-hour costs that month. Lowering the contract pays only if the battery holds the new value in every quarter-hour of the year: Liander treats an overrun as a request to raise the contract, and an overrun within 12 months of a reduction can be applied back to the date of the reduction (Liander 2026).

At €61–73 per kW a year, a battery that only shaves peaks has a long payback. The illustrative example in the guide below, a 100 kWh battery holding 60 kW off a 400 kW site, saves about €3,200 a year net and pays back in about 14 years before ageing.

Full rates and that worked example: Dutch large-connection tariffs: kW contract, kWmax and kWh.

Why the connection decides the case

On a connection that cannot grow, the battery's value is the load it lets the site add, or the upgrade it replaces. An illustrative office, not a real customer: a 150 kW contract, a heat pump and 10 EV chargers that would push winter mornings to 210 kW (assumptions).

1. Excess above the limit: about 60 kW for about 3 hours, 60 × 3 = 180 kWh.
2. Usable energy at 95% discharge efficiency: 180 ÷ 0.95 ≈ 189 kWh at least. A 100 kW / 250 kWh battery covers it with about a third to spare.
3. Recharge: to deliver 180 kWh at 90% round trip the battery draws 200 kWh. With the office at 90 kW at night under its 150 kW limit, 60 kW is free and refilling takes about 3.3 hours.
4. Bill value: 60 × €3.57 × 12 = €2,570 a year on the kWmax, plus 60 × €2.29 × 12 = €1,649 for the contract increase it avoids, if that increase was even available.
5. Growth value: the site can install the heat pump and chargers now instead of waiting for the grid. That is the number the client weighs, often against an upgrade quote or a waiting time.

Sites that went this way, as reported by a trade magazine or the vendor:

• De Walvis office, Amsterdam: a 320 kWh battery on a 137 kW connection with peaks of about 200 kW, installed to avoid disconnection (Solar Magazine, 27 Apr 2024).
• Albert Heijn distribution centre, Zaandam: more than 1.8 MWh / 800 kW for electric trucks and DC chargers after the contracted capacity was reached (vendor: Intercel).
• Oomen Warehousing: a battery avoided a new substation that would have taken about two years (vendor: Tesvolt).

The method step by step: sizing for a connection limit.

What the ACM draft changes from 2028

On 8 October 2026 the ACM published a draft decision on time-dependent transport tariffs for large connections, with comments open until 18 November 2026 (ACM consultation). It is a draft; the final text can change. What the draft says (ACM draft):

• Intended start: 1 January 2028.
• The kWmax becomes a weighted kWmax: each quarter-hour's kW is multiplied by a weight for its month, hour and type of day (0.10, 0.25, 0.58, 0.82 or 1.00), and the highest weighted quarter-hour of the month sets the charge.
• The weight 1.00 falls on working days from November to February, in the morning and from late afternoon into the evening; the early afternoon of summer working days and much of summer weekends carry 0.10.
• The kWh charge becomes time-dependent in five levels with the same ratios.
• For categories a to d, the transport charge would be split 50% on contracted kW and 50% on the weighted kWmax.
• Small connections would follow from 1 January 2029 under a separate draft (ACM draft, small connections).

What is not known: the price per weighted kW in 2028. The battery coalition's response to the draft argues it is not clear that it will equal today's kWmax rate (zienswijze Batterijcoalitie).

What that means for sizing

Illustrative arithmetic, not a real site: a site draws a flat 1,000 kW with a 1,500 kW peak at midday in summer.

• At night, weight 0.58: 0.58 × 1,000 = 580 kW weighted.
• Summer midday peak, weight 0.10: 0.10 × 1,500 = 150 kW weighted.
• The month's charge is set by the 580 kW at night. Shaving the summer midday peak would earn nothing on the kW charge.
• Charging the battery at night with 100 kW would raise the weighted value to 0.58 × 1,100 = 638 kW. Under the draft, when the battery charges matters as much as when it discharges.

Zorowatt's reading of this: a battery sized today to shave the highest quarter-hour of each month may be shaving the wrong hours from 2028, while a battery sized to hold the connection limit has to hold it in every quarter-hour regardless of weights. The cable and the transformer are the same in 2028. That is why Zorowatt sizes Dutch sites on the connection first and treats 2028 as a scenario with an editable rate, never as a fact.

What else a Dutch battery can earn

• The ESNL / Ecorys study lists the use cases Dutch business batteries serve: peak shaving, self-consumption, spot and imbalance trading, and bridging while waiting for a connection (Energy Storage NL & Ecorys).
• Dynamic contracts: SolarPower Europe's June 2026 outlook puts their uptake among non-household customers below 10% (SolarPower Europe). Arbitrage needs one, or a supplier price that follows the day-ahead market.
• Tax: the same outlook lists the Energy Investment Allowance (EIA) as a deduction of up to 45% of eligible investment (SolarPower Europe). Check the current conditions with RVO before counting on it; RVO has a page on investing in a battery under netcongestie (RVO).

Tools for a Dutch connection study

• Tibo, a Dutch energy management company, offers a free quick check of the grid connection and simulations on the previous year's real data; installers and advisors can resell its system (Tibo, read 2026-10-28).
• Zorowatt carries Liander's, Stedin's and Enexis's 2026 tariffs, each with its source, and the ACM 2028 draft as a scenario: the weighted kWmax with the ACM weights and the €/kW rates assumed equal to 2026, labelled as an assumption. Its connection-limit mode is the default for Dutch tariffs: add the new load, set the limit, and it finds the smallest battery that holds it with zero breaches, or says that none does. Zorowatt wrote this article; for how it compares with other planning tools, see Furo vs Zorowatt and HOMER Grid vs Zorowatt.

Checking a Dutch site, step by step

1. Get 12 months of quarter-hour data (kwartierwaarden) from the metering company or the supplier portal, and check it with the free meter data checker.
2. Ask which limit is enforced: the contracted transport capacity, the physical connection, or a flexible contract with its own hours.
3. Write down the new load: what, how many kW, in which hours and months.
4. Run the Workspace in connection-limit mode under the operator's 2026 tariff and check the rebuilt bill against the invoices.
5. Run the same battery under the 2028 scenario and look at which hours now set the charge, and when the battery charges.
6. Value the result against the alternative: waiting, an upgrade quote or moving the load. The decision is the client's.

Sources

• Solar Magazine, grid waiting lists, 6 Oct 2026
• Energy Storage NL & Ecorys, Marktonderzoek Energieopslag 2025
• Liander, tariffs for connection and transport, large consumers 2026
• Stedin, tariffs 2026 large consumers and Vergoedingsregeling 2024
• Enexis, large-business tariffs from 1 Jul 2026
• ACM, draft decision on time-dependent tariffs for large connections, 8 Oct 2026, consultation page, draft for small connections
• Batterijcoalitie, response to the ACM draft
• SolarPower Europe, European Battery Market Outlook 2026–2030
• RVO, investeren in een batterij
• Solar Magazine, De Walvis, 27 Apr 2024; Intercel, Albert Heijn Zaandam (vendor); Tesvolt, warehousing case (vendor)
• Tibo

Last checked: 2026-10-30. Facts about other tools were read on 2026-10-28 from the pages linked next to them; prices and features change, so check the vendor's page before you rely on one. Examples marked illustrative are not real customers. The ACM decision is a draft on the date above; check the final text before relying on a 2028 figure.