We used the RTOS (real-time one-sweep) method for I-V measurement, which derives the results with better accuracy by eliminating the capacitance effect in real time. We also used this method to compare emerging PV cells exhibiting promising power conversion efficiency and no hysteresis behavior under indoor lighting simulator with solar simulator. In this study, we defined performance ratios to compare indoor lighting with solar illumination. The indoor/outdoor ratios show different trends depending on the PV device type, which could highlight the specific type of PV that harvests better under indoor lighting and is preferable to indoor applications.