A prototype of a low‑cost solar‑grid utility hybrid load sharing system for agricultural DC loads

The main objective of this work is to design a prototype of a low-cost solar-grid utility hybrid load sharing system to support the agricultural DC equipment that has already been used in the rural area of Thailand. Time-division multiplexing (TDM) technique is employed in the prototype construction, and it is used to evaluate the time interval for two power MOSFETs to switch between two applicable power supplies: in this case, solar panels and grid utility. The time interval is generated by the internal timer from a microcontroller and is divided into two square waves which are 180° out of phase (opposite sides). Each time interval is derived by the fuzzy logic controller and is calculated based on the consumption of electrical load. The experimental results are divided into three parts; first result shows a smooth output level that is consisted of the signal between solar panels and grid utility for each particular ratio. The second result shows a high efficiency of this system upon the variation of load power. Finally, we demonstrate a relatively good sharing of the electrical power when this system is operated under various capacities of the power sources. Our prototype offers the feasibility of hybridization of renewable energy and grid utility in which the technology is easily accessible by agriculturists throughout the world.