In Solar Off-grid PWM PCU, when the sun rays hit the solar panel, it leads to the generation of DC power which converts usable AC power for the functioning of the connected appliances. The surplus DC power is secured in the battery in case of a power cut. The solar charger controller which is inbuilt ensures appropriate battery charging and restrain the reverse flow of current to the solar panel. PWM means Pulse Width Modulation which is used as one method of float charging. It sends out a series of short charging pulses to the battery- a very rapid “on-off” switch. The controller continually checks the condition of the solopower UPS battery.