What is Ups/inverter efficiency?

The energy efficiency of UPS system/inverter is the difference between the amount of energy that is used by a UPS system and the amount of useful energy that it delivers to power loads.

In all UPS systems, some amount of energy is lost as heat when it passes through the internal components of the UPS (transformers, rectifiers, inverters, etc). The amount of energy lost between the input and output can be significant when you consider the costs of the wasted energy. Energy efficiency advantages of as little as 1 per cent between one UPS and another can translate into thousands of rupees saved per year, depending on the size of the UPS.