This paper presents a fast and accurate approach for the dynamic electrothermal analysis of photovoltaic (PV) plants with a cell-level discretization. A circuit model is developed for the elementary cell, and an equivalent electrical network is automatically built in a preprocessing stage to account for the power-temperature feedback. The PV plant under analysis is represented as an electrical macrocircuit that can be solved with low CPU/memory requirements and without convergence issues by using any SPICE-like simulator. The proposed strategy can be successfully exploited for diagnostic purposes.