Photovoltaic powered uninterruptible power supply using smart relay

Uninterruptible power supply (UPS) sits between a power supply such as wall outlet and devices to prevent undesired feature that can occur within the power source such as outages, sags, surges and bad harmonics from the supply to avoid a negative impact on the devices. This paper presents a photovoltaic (PV) powered UPS using smart relay. It is a standby UPS whereas if the main power source fail to supply power to loads, a battery powered inverter turns on to continue supplying power. The battery is charged by the PV using solar charger and transfer switch controlled by smart relay. The UPS was tested to a load of 240 V, 20 W AC aquarium water pump. The test result shown that the UPS perform well, when the main power source fail, the battery could power inverter and the smart relay control the transfer switch, the load and battery current were 0.1 A and 1.56 A, respectively.