This paper quantitatively evaluates different distributed maximum power point tracking (DMPPT) photovoltaic (PV) systems in mismatch cases. To help designers obtain the full benefits of the DMPPT concept, a general analysis of the optimal power region (OPR) in different DMPPT system configurations is undertaken. Taken into account in the evaluation of OPRs are functional constraints derived fromDMPPT converters, mismatch conditions, and system architectures and parameters of related PV units. To simplify the calculation process and enable rapid discovery of OPRs, judging criteria are proposed for 4 DMPPT structures. If the judging criteria are met, DMPPT PV systems can extract ideal maximum power regardless of mismatch issues. Finally, experimental results are provided to show the effectiveness of the proposed static models, formulas, and judging criteria.