We determine uncertainty in photoconductance (PC) measurements of the emitter saturation current density (J0e). A Monte Carlo method is used to calculate the impact of uncertainty from the input parameters including the test equipment calibration, the intrinsic-recombination model, and the measured sample's thickness, doping, and optics. The uncertainty in the measurement of J0e is calculated, where we find that the sensitivity to input uncertainty depends on the measurement mode, transient decay, or quasi-steady-state PC. For quasi-steady-state measurements, the uncertainty in J0e is largely affected by thickness and generation uncertainty. For transient measurements, thickness uncertainty dominates the uncertainty in J0e. The wafer doping and measured voltage data has little impact on the resultant J0e uncertainty. We find, in our case study, that measurements of J0e to be accurate within 3%-6% when using the transient mode, and 4%-7% using the quasi-steady-state mode.