A portable modified pyramid solar still (PMPSS) has been developed to provide high-yield, low-cost freshwater in mountainous, arid, and off-grid regions. The unit integrates seven enhancements: concave stainless-steel mirrors for solar concentration, phase-change material for latent heat storage, a wave-maker for bulk mixing, an ultrasonic fogger for fine spray generation, a dual-pyramid cap-cooling system for effective condensation at the apex, thermoelectric modules for targeted basin heating and auxiliary cooling, and a droplet-feed layer for uniform shallow brine distribution. Field trials were conducted in Sanandaj, Iran (35.3◦N; September 2022), and compared against a conventional pyramid solar still (CPSS). The PMPSS achieved a yield of 4.64 L m 2⋅day 1—an 88 % increase over the CPSS—along with energy and exergy efficiencies of 34.1 % and 2.4 %, respectively. Moreover, the levelised cost of water was reduced to $0.089/L. These integrated enhancements make the PMPSS a cost-effective and scalable solution for providing reliable freshwater in remote mountainous and arid areas. 1.
