Theoretical basis of Photoconductance Decay and Surface Photovoltage Techniques is presented. Impact of typical measurement set-ups and sample preparation procedures on the differences observed in experimental results which include diffusion length, recombination lifetime, and bulk iron concentration is emphasized. Measurement accuracy and evaluation repeatability for both techniques is simulated. Relevant experimental evidence is presented based on a variety of samples with different intentionally introduced metal contamination, oxygen levels, and surface electrical properties.