Why German and Dutch project teams ask the same four questions

Almost every enquiry we receive from Germany and the Netherlands starts the same way: a hydrogen demand figure in Nm³/h, a 400 V three-phase supply, a roof or container footprint, and a deadline tied to a commissioning window. What follows is rarely about price. It is about four things: what exactly is inside the battery limit, whether the stack voltage matches the local grid, which CE documents the notified body will ask for, and how the plant will be maintained through a North Sea winter.

This guide answers those four questions for large electrolysis cell stacks and complete hydrogen generation systems. The regulatory references below are written for Germany and the Netherlands specifically; they are not global conclusions. Sites in other markets face different rules, and we treat them separately.

1. Where a stack ends and a system begins

A large electrolysis cell stack is the electrochemical core: membrane electrode assemblies (MEAs), bipolar plates, porous transport layers, end plates, tie rods, insulation and gas manifolds. It produces hydrogen, but it cannot run on its own. It needs treated water, a controlled DC supply, cooling, gas–water separation, and a safe shutdown path.

A complete hydrogen generation system wraps that core with water purification, a rectifier or DC power module, water circulation and cooling, gas–liquid separation, drying and purification, instrumentation, PLC/HMI control, gas detection, ventilation interlock and the enclosure. Buyers who compare a stack price against a system price are comparing two different scopes — a frequent source of misunderstanding in tenders.

2. Cell count, voltage and the 400 V reality of German and Dutch sites

Stack voltage is not a design preference; it is arithmetic. Each PEM cell sits at roughly 1.7–2.0 V at practical current densities, so the number of cells sets the stack voltage, and the active area sets the current:

• Stack voltage ≈ cells * cell voltage (e.g. 60 cells * 1.8 V ≈ 108 V DC)
• Stack current ≈ current density * active area (e.g. 1.5 A/cm² * 1,000 cm² ≈ 1,500 A)
• Specific energy consumption typically falls in the 4.5–5.0 kWh/Nm³ range at 1.0–1.5 A/cm², rising at higher current density

A 0.5 Nm³/h stack (roughly 2.5–3 kW) can run from a single-phase 230 V supply through its own power module. A 50 Nm³/h unit (roughly 250–300 kW) already needs a 400 V three-phase feed with a dedicated rectifier. Above a few hundred Nm³/h, German and Dutch sites normally move to a 10 kV or 20 kV medium-voltage connection with a dedicated transformer; the rectifier front end then has to be specified for harmonic behaviour, not just efficiency.

For CE compliance, the relevant EMC standards for industrial environments are EN 61000-6-2 (immunity) and EN 61000-6-4 (emission). Ask for the test report, not the declaration alone: a 12-pulse or active-front-end rectifier behaves very differently from a simple six-pulse bridge on a weak grid connection.

3. MEA and water: the two variables that decide stack life

The MEA carries a perfluorosulfonic acid membrane, an iridium-based oxygen evolution catalyst on the anode, and a platinum-based hydrogen evolution catalyst on the cathode, with titanium sinter on the anode side and carbon-based transport layers on the cathode side. Two operating disciplines dominate service life:

Water quality. Feed water should meet a laboratory-grade specification such as ASTM D1193 Type II or ISO 3696 grade 2, with conductivity kept below 1 µS/cm at the inlet and typically near 0.1 µS/cm in the loop. Calcium and iron ingress contaminates the membrane and raises cell voltage permanently — this is the single most common cause of premature stack replacement we see in the field.

Gas purity and cross-leak control. Product hydrogen is typically 99.9–99.99% at the stack outlet and reaches 99.999% after catalytic purification and drying, with dew point around −60 °C to −70 °C. ISO 22734:2019 treats gas cross-contamination as a safety function and requires the system to monitor it and shut down on defined limits; a hydrogen-in-oxygen analyser with an interlocked shutdown is therefore part of the system scope, not an option.

4. Reading a polarization curve properly

A polarization curve is the only honest performance document a supplier can give you. Read it in three parts: the low-current intercept (activation behaviour and catalyst quality), the linear middle slope (area-specific ohmic resistance — lower is better), and the high-current tail where mass transport losses appear. A curve measured at 20 °C tells you very little about a unit that will run at 60–80 °C.

Request curves at beginning of life and at the end of the warranty period, at two or three temperatures, and with the test stand's water quality stated. If a datasheet shows only a single efficiency number with no curve, the number cannot be verified.

5. Compliance map: Germany and the Netherlands

The following references apply to installations in Germany and the Netherlands. They are cited by number because a project engineer will be asked for them during permitting and handover.

Two practical notes. First, a CE declaration covering only the enclosure is not a system declaration — the stack, rectifier, water treatment and gas train must all sit inside the technical file. Second, documentation language matters: German authorities and Dutch occupational safety inspectors expect operating manuals in the local language, and Dutch projects routinely require an English–Dutch document set at handover.

6. Where the hydrogen actually goes in these two markets

Renewable coupling in Germany. Electrolysers are increasingly sized against curtailment and negative-price hours rather than baseload. That changes the specification: fast ramp from cold, wide turn-down, and a stack that tolerates frequent start–stop without excessive voltage decay. A unit optimised for continuous baseload operation is the wrong purchase for this duty.

Industrial supply in the Netherlands. Port and chemical clusters along the Dutch coast are being connected to a national hydrogen backbone, and electrolysers there feed refinery, ammonia and methanol users. Purity and pressure at the battery limit, plus metering and custody-transfer documentation, matter as much as efficiency.

Mobility and laboratory use in both markets. Fuel cell test benches, filling stations and research institutes need fuel-cell-grade hydrogen per ISO 14687:2019, which usually means the purification stage — not the stack — sets the achievable specification.

7. Sizing and maintenance checklist

8. What verifiable manufacturing evidence looks like

Shandong Saikesaisi Hydrogen Energy Co., Ltd. has focused on PEM hydrogen technology since 2007. Production sits in a single plant that covers laser cutting, automatic welding, CNC machining, final assembly, instrumentation and control, and final inspection — which means process traceability stays inside one quality system rather than being split across subcontractors. Annual capacity exceeds 200 hydrogen generation systems. The QLS-H and QLS-M series cover single-stack capacities from 0.5 to 500 Nm³/h, and the company operates under ISO 9001:2015 with CE and EAC certification.

Before shipment, each system is run on the test stand, its polarization curve is recorded, the gas train is helium leak-tested, product purity is measured, and insulation resistance is checked. Those records — not adjectives — are what a German or Dutch project engineer should ask to see, and they can be matched against the witness test plan agreed at order stage.

9. Conclusion

For a German or Dutch project, the technical decision usually comes down to three specifications: stack voltage and rectifier matching for the available 400 V or medium-voltage supply, a documented water-quality discipline that protects the MEA, and a CE technical file that covers the whole system under EN ISO 22734:2019 with the correct PED, ATEX, EMC and low-voltage directives. Get those three right and the commercial comparison becomes meaningful. Get them wrong and the cheapest offer on the table becomes the most expensive unit in the plant.

FAQ

Do I need a notified body for a PEM electrolyser in Germany?
Not always. It depends on the pressure-volume category under Directive 2014/68/EU and on the ATEX classification of the installed area. Low-pressure, small-volume systems often allow self-certification; larger buffer vessels usually do not.

Can a 230 V single-phase supply run a 5 Nm³/h system?
Typically not at that capacity. Roughly 25 kW of stack power exceeds what a standard 230 V single-phase circuit should carry continuously, so a 400 V three-phase feed is the normal choice in both countries.

How often should the MEA be replaced?
It is an operating-hours and water-quality question, not a calendar one. With clean feed water and stable temperature control, stacks in intermittent industrial duty commonly run for several years before voltage decay justifies replacement; the cell voltage trend, not a fixed date, should trigger the decision.