A 1kW Transformerless Inverter with a Microcontroller-based Battery Charging System for Off-Grid Photovoltaic Modules

In off-grid photovoltaic systems, the reduction of the size and weight of an Inverter is a challenging issue. A Transformerless inverter is a smart solution to this problem. Therefore, in this work, a 1kW off-grid inverter is implemented which is transformerless and integrated with a battery charging facility. A microcontroller-based controlling unit is used for both the proposed inverter and battery charge controller. The inverter is tested in a laboratory environment using a 40W photovoltaic (PV) panel. An indoor sunlight source is developed to generate sunlight as the PV input. The PV module output is examined by a professional PV system analyzer, PROVA 1011. The experimental results show that the inverter is working at 98.7% efficiency to operate an AC load from a battery. Besides, the battery charging current and voltage is monitored by an LCD. Finally, over-voltage and current protection units are tested to validate the reliability of the protection unit of the proposed inverter.