A method is presented to characterize the TCO/p contact and the TCO sheet resistance in a-Si based p-i-n superstrate devices. It requires having scribed TCO strips, which are electrically isolated before a-Si deposition, then fabricating rows of individual devices on each strip. Analysis of 4-terminal measurements in different V-sensing configurations yields the TCO/p contact and TCO sheet resistance in a straightforward manner. The method is applied to devices fabricated on 3 brands of commercial SnO2 substrates. The TCO/p contact resistance is found to be ~2 Ω-cm2 and the sheet resistance decreases by 2-4 Ω/sq after a-Si deposition on all 3 brands of SnO2 substrates.