Interfacial solar evaporation has received extensive attention for sustainable seawater desalination. Despite great progress in interfacial solar evaporators (ISEs) with high evaporation performance, the poor collection of the dynamic evaporation rate of exact ISE in large scale application as well as the monitoring of the salt precipitation still face great challenges. Herein, the electrical conductivity of the supporting substrate is firstly employed as an indicator to monitor the real-time and in situ evaporation rate of an ISE. This method is based on a linear dependence between the electrical conductivity and the evaporation rate, both of which are dependent on the fluid flow as well as the ion mobility inside the supporting substrate. Moreover, the electrical conductivity-based evaporation rate monitoring is generally applicable for various kinds of ISEs. As a proof-of-concept, six evaporators in a prototype system were simultaneously managed by in situ tracking each electrical conductivity over time. Furthermore, the salt clogging inside the ISE can be sensitively detected almost 30 min earlier than the observation of salt crystals on the ISE surface. Based on its easy accessibility, wide applicability, good stability and high accuracy, this in situ evaporation rate monitoring has important implications to promote the intelligent management of large-scale ISEs.