Membrane distillation (MD) is a promising solution for the recovery of low-grade waste heat, by driving a separation process that uses hydrophobic porous membranes to allow for the vaporization at the interface with a heated feed stream, with subsequent diffusion through the pores into the cold permeate side of the membrane. Due to the ability of operating at low temperature ranges and handling high salinity solutions, MD has been studied as an alternative technological route to be used for desalination with available low exergy heat. In the Vacuum-enhanced Air Gap Membrane Distillation (V-AGMD) configuration, due to an air gap between the membrane and the condenser plate and the use of a supplementary system to promote vacuum in the distillate channels, high thermal efficiency can be achieved by reducing conduction losses and leading to increased distillate fluxes as compared to the more conventional Air Gap Membrane Distillation (AGMD) configuration. Thus, the present study is aimed at performing the experimental characterization of a pilot system (TRL6) for a solar desalination system with a V-AGMD spiral module combined with a flat solar collectors assembly as the thermal energy source for heating the feed stream. The experiments were performed for 7 h/day subjected to real atmospheric conditions with variable irradiation conditions, as the thermal drive for the desalination process. The influence of the operating parameters such as feed stream inlet temperature, circulation flow rate (400 l/h - 650 l/h), absolute pressure in the air gap (513 mbar and 1013 mbar) was evaluated by monitoring the performance parameters for productivity (distillate flux), quality (rejection coefficient), and thermal efficiency (specific thermal energy consumption and output gain ratio), with an inlet NaCl concentration around 10 g/l in the feed solution. The chosen initial NaCl concentration level represents the desalination process of streams from low salinity wells typical of the Brazilian northeastern semi-arid region. Experiments carried out under different irradiation conditions have demonstrated the direct dependence of distilled water production on solar irradiation. The previous storage of thermal energy enabled the starting and maintenance of the MD process with higher feed stream temperatures, reaching a production 42% higher than the production of the experiment without the previous thermal storage. The circulation flow rate demonstrated a positive impact on the distilled water production. However, it promoted a reduction of the thermal efficiency of the process. Furthermore, the reduction of the absolute pressure in the air gap showed a positive impact on the performance parameters, except for the rejection coefficient. Values above 99.96% were obtained for experiments with 1013 mbar air gap absolute pressure.