• Novel off-grid PV system stores excess energy as hot water during the day. • The method integrates efficient direct coupling with a flexible inverter-battery unit. • Energy stored thermally reduces unused solar power by more than 47%. • System tested experimentally on a six-panel setup in Amman, Jordan. • Configuration lowers cost, battery use, and dependence on household consumption behavior while improving system efficiency. According to the International Renewable Energy Agency, the future to enhanced sustainability will be for off-grid renewable energy systems, with improved performance and methods of energy storage at reduced costs. Off-grid systems have the advantage of resilience and being independent of major grid infrastructures or the need for grid connection permissions. They are also useful in rural areas, especially in developing countries, where the electricity grid may be unstable or even non-existent. The performance of off-grid energy systems depends primarily on the behaviour of household consumption during the day. In PV systems, direct coupling is more efficient and cheaper but less flexible, while using inverters and batteries is more flexible but less efficient and more costly. This research employs a hybrid approach, using part of the PV energy as a direct connection to heat water and the rest through a conventional hybrid inverter. The objective of the project is to improve the performance of renewable energy systems that use off-grid photovoltaic (PV) panels by exploiting what is called “the non-captured energy” that is dependent on the capacity of the installed battery. The novel idea is based on storing energy in the form of hot water in a thermal storage during the day by taking a small portion of the photovoltaic system’s capacity and connecting it directly to the heating element in parallel with the inverter. The methodology used includes testing the novel approach using an experimental work in Jordan as a case study, as it meets the criteria that have been developed for testing the technology. The results of the study over a one-year period demonstrate a significant improvement in the off-grid system's performance by effectively utilising further solar energy capture beyond the capacity of the batteries, reducing the non-captured energy by more than 47% when compared with a conventional system of the same size and battery capacity. The new configuration does not require expensive equipment and also reduces the cost, the capacity and the number of batteries needed to obtain a similar performance using conventional systems. This suggested novel hybrid configuration may have the potential also to expand its use in other applications, such as cooling systems and energy storage in different forms, such as sand batteries and water cooling.
Moh’d et al. (Sun,) studied this question.