This communication discusses the energy, exergy, and economic feasibility of novel heat storage based on a single-slope solar still coupled with a solar air heater (SAH). The analysis was conducted on three different solar stills, i.e., a single-slope solar still (SSSS), single-slope solar still with latent heat storage, and a single-slope solar still with latent heat storage coupled with a solar air heater. The performance evaluation of all types of solar still has been compared to evaluate the best-performing solar still. Paraffin wax as a phase change material (PCM) has been used at the bottom of the solar still to provide proper thermal storage. The experiments were conducted on different depths, i.e., 3 cm, 6 cm, 9 cm, 12 cm, and 15 cm. The efficiency of a single-slope solar still with PCM and SAH was 65.58% higher than a conventional solar still. The average exergy efficiency of a single-slope solar still with latent heat storage coupled with a solar air heater is 83.19% higher than a traditional solar still. Additionally, the maximum hourly output was found to be 735 mL/m² h for the solar still customized with PCM and solar heater for a depth of 3 cm. This shows that the still (single-slope solar still with latent heat storage coupled with a solar air heater) has higher thermal performance than the other two solar stills. Therefore, the proposed solar still is very suitable for desalination.

A parabolic trough collector (PTC) is a linear concentrating system consisting of a parabolic-shaped reflector with a receiver tube positioned along the focal axis. In this study, the performance of a parabolic trough solar collector is evaluated, with aperture area, collector length, breadth, Rim angle, and inner and outer absorber diameters of 5.54 m², 3.65 m, 1.52 m, 70°, 0.048 m, and 0.05 m, respectively. The experiment was conducted at Ranchi, India (23.35° N and 85.30° E). During this day, marked by a cloudless sky, the ambient temperature ranged from 27 °C to 39 °C. The global solar radiation ranged from (630 W/m² to 975 W/m²), and the wind speed varied between (0.8 m/s and 1 m/s). Aluminium oxide (Al₂O₃) and Therminol VP-1-based nanofluid were employed as the working fluid. The different volume fractions of nanoparticles were taken, and the evacuated tube PTC performance was analysed. When Al₂O₃–Therminol VP-1 of varying concentration (0–4%) and mass flow rate of 0.041 kg/sec is used, it has been observed that the receiver’s heat transfer performance improved with an increment in nanoparticle volume fraction. Temperature-dependent properties were applied to the thermal efficiency, exhibiting a notable increase of approximately 7.2% when the volume fraction ascends from 0 to 4%. At elevated Reynolds numbers, the efficiency decreases compared to lower volume fractions. These results contribute to understanding the effect of nanoparticle concentration on PTC performance.