Inverter/UPS Selection

What Capacity of Inverter is Good for Your Home?

Once you are sure that you are looking for an Inverter, it's important to calculate the capacity of Inverter that will suit your requirement. Following table will give you brief idea about the power consumed by various equipments.

Tubelight - 60W

Fan - 70W

Television - 120W

Laptop - 100W

CFL - 25W

Modem - 50W

Now you are in a position to understand as what capacity inverter do you need and I'll let you do that in 3 simple steps -

1. CALCULATING YOUR POWER NEED

Now I'll explain you how to use above table to calculate the right capacity Inverter for your need. Let's say you need Inverter to run 2 Tube lights, 3 Fans, 1TV and 1 Laptop. As per the table above, you'll need a total power of 550W(=2X60 + 3X70 + 1X120 + 1X100) to support all of your equipments at the same time.

♣ Your Total Power Need = 550W

2. CALCULATING REQUIRED INVERTER'S CAPACITY

Now that you know how much power is required, it's easy to get the VA rating of inverter. In ideal condition, the VA rating would have been same as the power need i.e. 550VA. But in practical conditions, the power factor of Inverter is less than 1 hence power supplied by 550VA Inverter won't be 550W but lesser than that. Assuming power factor of Inverter to be 0.7, following are the details of calculation -

Required VA of Inverter X 0.7 = 550W

♣ Required VA of Inverter = 550/0.7 = 786 VA

Now luckily we have inverters available in the market with 800VA capacity, so such inverters will fit into my requirement.

3. CALCULATING BATTERY CAPACITY

Till now, you will have clear understanding of the Inverter capacity required for your need. But the next question is that how much back up will the inverter provide and for how many hours you can run all of your equipments. And that's where battery capacity comes into picture. It's the battery which determines the back-up hours. The higher capacity battery you have, the more back-up hours you'll get. So lets get into the calculation fast.

Required power(in Wattage) X Required back-up hours(in Hours) = Inverter Voltage(in Voltage) X Battery Capacity (in Ampere Hours)

Let's look for an Inverter which can give back-up of up to 3 hours, so for our case -

550W X 3Hours = 12V X Battery Capacity

♣ Battery Capacity = (550 X 3)/12 = 137 Ampere Hours

So we need a battery of 137AH capacity but if you check the market you'll find batteries of 130AH capacity. So that should be more or less sufficient for your need.

Conclusion

Finally, we have come to the conclusion that if we go for 800VA Inverter with 130AH battery, I can run 2 Tube lights, 3 Fans, 1 TV and 1 Laptop for up to 3 hours. And by the end of this article you don't need to rely on sellers for understanding your need as you can do the calculations yourself in just 3 simple steps. Hope this article helps you in some way in making the right decisions. Let me know if you need any other inputs.