Enhancing nocturnal productivity holds promise for boosting the effectiveness of solar desalination setups. Current research concentrates on an innovative strategy: the integration of paraffin wax and Jatropha biodiesel as a composite energy storage material (CESM) to amplify distilled water output during nighttime. The composite material, comprising Jatropha biodiesel and paraffin wax in a 1:1 ratio by weight, is meticulously examined for its impact on productivity, juxtaposed against a conventional solar still (CSS). Results reveal a substantial improvement in thermal conductivity with CESM, exhibiting a noteworthy 20.37%% surge compared to pure paraffin wax. Furthermore, a solar still with biodiesel and phase change material (SSBDPCM) is pitted against a CSS, with continuous monitoring of water and absorber temperatures alongside distillate production. The findings illustrate that SSBDPCM achieves a 16% upsurge in water temperature and a 10% elevation in absorber temperature compared to CSS. Impressively, SSBDPCM achieves a staggering 63% increase in distillate production, yielding 3.6 l/m2 and 3.4 l/m2, in sharp contrast to CSS, which only manages 2.2 l/m2 and 2.1 l/m2 over a two-day test period. Furthermore, a comprehensive cost analysis showcases the economic superiority of SSBDPCM over CSS. SSBDPCM demonstrates a compelling 29.2% reduction in cost per liter and a significant 25.9% decrease in the payback period in comparison to CSS. These compelling outcomes underscore the substantial potential of the SSBDPCM approach in delivering heightened efficiency and cost-effectiveness, paving the way for a promising advancement in solar stills.