Definitions and difference between Power and Energy Units in Electrical Engineering
It is the measure of electrical current at the moment. Amps are important to determine the wire size for connecting the inverter to the battery. Low gauge wire will heat up and burn if heavy current flows through it from the battery.
Amp-Hour is mainly used in batteries usually abbreviated as Ah is the Amps x Time. Ah is the measure of battery capacity which determines the backup time of the inverter.
this is simply use for the maximum load capacity of the inverter system. Commonly available inverters are 500 VA, 800 VA, 1000 VA, 1500 VA, 200VA, 3000VA etc.
Watt is the measure of how much power a device uses when turned on or can supply. If a device uses 100 watts, it is simply the voltage times the ampere (rate of current). Watt is unit for Electrical power measurement.
If the device takes 10 Amps at 12 Volt DC, it uses 120 watts power. That is 10A x 12 V = 120 W.
A watt hour (or Kilo Watt hour – kWh) is simply how many watt times, how many hours the device is used. This is unit for measurement of Electrical Energy Consumed.
If the device uses 200 watts for 10 hours, it is 2000 watt hour or 2 kWh and our power companies usually use this for their metering.