This work aims to improve the productivity of solar still unit (SSU) by multiplying the supplied heat energy. Experiments are carried out daily from 10 AM to 3 PM using heating air, which simulates the exhausted gases from engines, boilers, or any other source. Several mass fluxes (up to 63.5 kg/s.m2) of the air beneath the solar still unit are tested at constant inlet temperature. The results state that just applying the proposed external heating system augments the accumulated yield while the thermal efficiency is decayed when compared with the unmodified unit. Besides, increasing the heating air flow rate boosts both the system productivity and thermal efficiency. Another part of the experiments is occurred for the whole day with heating air system at mass flux of 63.25 kg/s.m2. For the modified unit, the outputs state that the change in the temperatures and freshwater yield are small along the day when compared with the reference one, in which the temperatures reach their peak values at 1 to 1:30 PM. The resulted accumulated yield over the whole day is increased from 3.16 l/m2 for the reference unit to be 13.48 l/m2. This increase corresponds to an enhancement ratio of 326.6%.