The dataset contains the experimental characterization of a multistage solar-driven membrane distillation system with direct ambient-temperature feed heating. It includes measurements of mass flow rate, temperature, permeate electrical conductivity, and mass evolution profiles used to calculate the distilled water production. The main file, provided in Excel format, contains steady-state data. The first sheet summarizes the key parameters used for system characterization, while the second sheet includes a schematic diagram and numerical values describing the laboratory conditions under which the experiments were conducted.