Hydrogen Electrolyzer & Fuel Cell Manufacturing calculator

Stack Assembly Yield Calculator

Estimate first-pass yield on the stack assembly line by entering the number of stacks that cleared leak, torque, and voltage checks, the number of stacks attempted in the same shift or week, and your internal first-pass yield target. The calculator returns the rate and the gap to target so you can decide whether the result is a normal day or a containment trigger.

What this calculator does

  • Estimate first-pass stack assembly yield for PEM, alkaline, SOEC, PEMFC, or SOFC stacks by comparing built stacks that pass leak, voltage, and torque checks against the total stacks attempted on the line.
  • Use it on the daily tier board when stack build cells, MEAs, bipolar plates, gaskets, and end plates have to flow through assembly with a known first-pass rate before warranty exposure builds up.
  • It returns the share of PEM, alkaline, SOEC, PEMFC, or SOFC stacks that cleared leak, torque, and electrical checks on the first attempt and the gap to your internal first-pass target.

Formula used

  • First-pass stack assembly yield = stacks passing first-time ÷ total stacks attempted × 100
  • Yield gap to target = first-pass yield - target first-pass yield

Inputs explained

  • Stacks passing first-time leak, torque, and voltage checks: Use stacks that cleared all in-process gates (cell stack-up, torque pattern, leak decay, open-circuit voltage) without rework.
  • Total stacks attempted in the same period: Use every stack started on the assembly line in the same shift, day, or week, including ones that needed rework or were scrapped.
  • Target first-pass stack assembly yield: Use the program quality target, contract commitment, or internal control limit (typical PEM stack assembly targets sit in the 92 to 98 percent range).

How to use the result

  • Run it daily or per shift after stack assembly closes the build, and before the team commits to schedule recovery, rework triage, or a containment action on incoming MEAs or bipolar plates.
  • It is an indicator, not a root cause. A low rate may come from MEA pinholes, gasket misalignment, off-torque end plates, plate flatness, or an out-of-spec compression set; confirm with leak decay traces and a torque audit before acting.

Common questions

  • What counts as a first-pass stack in this calculator? A stack that passed every in-process gate (cell stack-up, alignment, torque pattern, leak test pressure decay, open-circuit voltage, and any insulation check) on the first attempt with no rework loop, no re-torque, and no MEA replacement.
  • What yield target should I use for PEM, SOEC, or SOFC stack assembly? Mature PEM stack lines typically run 95 to 98 percent first-pass; new SOEC and SOFC lines often start in the 80s and improve as gasket, sealing-glass, or compression set issues are tuned out. Use whatever value sits on your program quality plan or contract commitment.
  • Why is my best shift above the target gap? The gap is just first-pass yield minus target. A positive gap means the line beat the target; a negative gap means it missed. It is not a percentage of the population.
  • Should I include stacks that were reworked and later passed? No. First-pass yield only counts stacks that passed without intervention. Reworked stacks should be tracked separately (use the stack rework cost calculator) so you can see the real assembly cost, not just final shipping yield.

Last reviewed 2026-05-12.