Electrolyser Sizing Calculator

Work out electrolyser sizing instantly with clear inputs, formula shown and shareable results.

About Electrolyser Sizing Calculator

Electrolyser rating is daily hydrogen demand times specific energy consumption, divided by the hours it will run, plus a design margin for degradation and turndown. Fewer operating hours means a larger and more expensive stack, which is why matching electrolyser hours to cheap electricity availability is the central design trade-off.

Formula

Electrolyser sizing

Power (kW) = hydrogen demand (kg/day) x specific consumption (kWh/kg) / operating hours, x (1 + margin)

Worked example

With the default values below, Electrolyser Sizing Calculator returns Electrolyser Rating of 2.4917. Change any input above and every figure here is recalculated in your browser.

Inputs used

Hydrogen Demandminimum 0 kg/day: 500 kg/day
Operating Hours Per Dayaccepts 0.01–24 hours: 12 hours
Specific Energy Consumptionminimum 0.01 kWh/kg: 52 kWh/kg
Design Marginaccepts 0–60 %: 15 %

Results

Electrolyser Rating: 2.4917
Power At Nominal Demand: 2.1667
Hydrogen Production Rate: 41.667
Daily Energy Consumption: 26,000.0

Step by step

1Values used
2Electrolyser sizing
3Electrolyser Rating= 2.4917
4Power At Nominal Demand= 2.1667
5Hydrogen Production Rate= 41.667
6Daily Energy Consumption= 26,000.0

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why does running for fewer hours cost more?

Capital cost scales with rated power. Halving operating hours doubles the stack size needed, so the capital cost per kilogram roughly doubles even though electricity may be cheaper.

What margin should be allowed?

10-20% for stack degradation over life, which raises specific consumption by around 0.5-1% a year, plus any need to exceed nominal demand during peak periods.