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Solar energy is a most promising resource of non-conventional energy to utilize for heating. Based on the application there are two kinds of utilization one is water heating and the second one is air heating. This is generally done by flat plate solar collector but due to its limitations to use in higher temperature ranges (i.e., 70-95 °C) and poor performance led to introduce the application of evacuated tube and parabolic trough collector. To fabricate the solar air heater, one ended evacuated tube is used as a receiver of the parabolic trough and U-tube copper pipe is inserted within the evacuated tube. The air heating process is done at various mass flow rates and it was found that the average outlet temperature was more at the minimum mass flow rate, but the average efficiency was less. At maximum mass flow rate, the average outlet temperature was minimum, and the average thermal efficiency was maximum. The maximum thermal efficiency obtained was 24.1% at the 0.0082 kg/s mass flow rate and the maximum temperature that was obtained was 151 °C at 0.0062 kg/s mass flow rate. Hot air being used for different application in space heating, food processing, fruits and vegetable drying and in regeneration of desiccant.

Being one of the major energy consumers, cooking is a necessary part of daily life. Non renewable cooking fuel sources, such as wood or cow dung cause hazardous pollution and a poor ecosystem worldwide. Over the past few decades, solar-powered cooking has undergone numerous improvements. Solar cooking has been predominantly used as a substitute for reducing oil and gas dependence, increasing environmental sustainability, and reducing global warming threats. This paper talks about the recent development of the box-type solar cooker. The paper discusses the principles and classifications of various parameters that affect the performance, energy, and exergy related to the solar cooking system. In line with the sustainable development goals of the UN agenda 2030 and especially the heed to the accomplishment of SDG 7 and SDG 13, various economic factors, such as the payback period (PP), net present value (NPV), benefit–cost (B–C) ratios, internal rate of return (IRR), levelized cost of heat (LCOH), and levelized cost of cooking a meal (LCCM) have been discussed. The environmental analysis has also been presented to show the overall benefit of solar cooking. The review also focuses on the current development of a box-type solar cooker, its components, and its heat transfer characteristic. Various geometrical modifications, the use of reflectors, and transparent insulating materials that improve cooking have been discussed. The concept of energy storage in the form of Phase change material (Latent heat storage) with the latest studied designs improvements of solar cookers has been obtained to be efficient, which also help in late-evening cooking. It can be said that with better policy implications, the social and economic acceptability of the solar cooker can be achieved.

Background: In the past 30–40 years, conflicts over limited conventional energy sources and the negative climate change caused by them have attracted researchers and analysts to new, clean, and green energy technologies. Thereby reducing the consumption of conventional fuel and the negative impact on the climate. The production of alternative energy in the form of thermal energy storage using phase change materials (PCMs) is one of the techniques that not only reduces the gap between the supply and demand of energy but also increases the stability of the energy supply. The tendency of PCMs to melt and solidify over a wide temperature range makes them more attractive for use in many applications. The effective and efficient storage of solar energy by PCM has the potential to significantly advance the use of renewable energy. Methods: Organic non-paraffin compound beeswax (BW) mixed with other non-paraffin compounds stearic acid (SA), Palmitic acid (PA), Myristic acid (MA), and Lauric acid (LA) in different compositions with the help of magnetic stirrer at 50–60°C for 3–4 hours to prepare BWSA, BWPA, BWMA, and BWLA eutectic PCM. Results: Prepared eutectics melt and solidify in the temperature range 36–56°C and with latent heat in the range of 155–211 kJ/Kg. Conclusions: Due to suitable temperature and good latent heat storage range, it is a good choice as thermal energy storage, for solar drying applications.