The following are the 2 Key specs of an Inverter:
VA – this value governs the type and number of appliances that you can use simultaneously when inverter is in use
Battery AH – this value signifies the number of hours the appliances can be used. Tubular batteries are preferred.
An 1100 VA inverter with a battery storage capacity of 150 AH shall enable usage of 4 fans, 4 lights and a mixer (intermittently) for 5 – 8 hrs which is generally more than sufficient.
However, using the below 3 step calculation, you can also scientifically arrive at the Inverter specs that you need:
- Find the total wattage of the appliances that you intend to use during power failure:
Approx wattage of common appliances: 1 fan – 75 watts , 1 LED tube light – 20 watts, 1 mixer – 350 watts, 1 LED TV – 100 watts
Total rated power if 2 fans, 4 lights, 1 mixer and 1 TV are in use: 2×75 +4×20 + 1×350 + 1×100 = 680 watts
- Arrive at the Power of inverter required
VA = total wattage/ efficiency = 680/ 0.7 = 971 VA
Hence, choose a nearest VA inverter.
- Calculate the battery capacity required:
Let’s say you want to use 2 fans, 2 lights and 1 TV for 5 hours, then:
AH = total watts * back-up hours required/ battery volts = 290*5/12 = 120 AH. Hence 120 AH battery is sufficient.
Typical AH value of inverter batteries in the market is: 100 Ah, 120 Ah, 150 Ah, 180 Ah, 200 Ah etc.