Fuel Cell Output Calculator

That is hydrogen's lower heating value (LHV) -- the standard reference figure used when the water produced by combustion or fuel cell reaction leaves as vapor rather than condensing, which is the normal case for fuel cell exhaust. It comes from hydrogen's LHV of 120 megajoules per kilogram, converted to kilowatt-hours (120 MJ / 3.6 MJ per kWh = 33.33 kWh/kg).

Adding stacks beyond the first introduces a small integration loss -- 0.5% per additional stack, up to a conservative cap of 5 percentage points total -- representing real balance-of-plant effects like manifold flow distribution mismatch between parallel stacks, which is why Overall Efficiency is always at or below Cell Efficiency and falls further as Stack Count rises until the cap is reached. Electrical Output is reduced by the same factor, so the headline output figure and the reported efficiency stay consistent with each other; the cap keeps this loss physically realistic even at the largest Stack Count values, rather than letting it grow without bound.

No -- Water Produced depends only on Hydrogen Flow Rate, using the fixed stoichiometric ratio of 9 kilograms of water per kilogram of hydrogen consumed (from the reaction 2H2 + O2 -> 2H2O). Cell Efficiency determines how the ENERGY from that hydrogen splits between electricity and waste heat, but it has no effect on how much water the reaction itself produces.

Yes -- Electrical Output uses Overall Efficiency and Heat Output uses the remainder (1 minus Overall Efficiency), both multiplied by the same Energy Input figure from Hydrogen Flow Rate, so the two always sum back to the full energy content of the hydrogen consumed. This includes any Stack Count integration losses, which show up as additional Heat Output rather than vanishing from the energy balance.

It multiplies Electrical Output by 8,000 hours per year, a commonly used planning assumption for continuous or near-continuous industrial fuel cell operation (roughly 91% uptime, allowing for scheduled maintenance). If your actual system runs fewer hours per year -- intermittent backup power, for example -- scale this figure down proportionally to your real expected run time.