Inverter and battery are required to manage power cut. The sizing of inverter and battery is important to have sufficient power and backup when needed. The selection of battery and inverter can be done in three simple steps :
Step-1, Calculate power requirement
Understanding power need is very important for selecting right size of inverter.
Make a list of all equipment you wish to run with the support of inverter like tubelight, Fan, TV, CFL, LED etc
Eg
| Equipment | Watt | No of Equipment | Total Watt |
| LED | 10 | 5 | 50 |
| Tubelight | 40 | 2 | 80 |
| CFL | 20 | 2 | 40 |
| Ceiling Fan | 80 | 5 | 400 |
| TV | 110 | 1 | 110 |
| 680 |
In the above eg 680Watt of power is required. Therefore our inverter must support 680watt of power requirement.
Step 2. Calculation of Inverter capacity
As we have calculated power requirement step 1, now we need to calculate VA requirement for the inverter.
For VA requirement we need to divide calculated power requirement by power factor, we may assume power factor as 0.8 for safer side calculation.
Considering 0.8 as power factor our inverter VA requirement shall be =680/0.8 = 850VA.
Now we should select next higher size inverter available in the market, say 900VA or 1000VA or 1200VA.
Step 3 Sizing of Battery
Inverter selection is done for the peak load, while battery is selected for duration of power requirement.
Size of battery is calculated by = (Load requiremt X Backup Hours) / Voltage
Where,
Load requirement = power load for inverter backup.
Backup hour = total hours backup in needed
Voltage = voltage of battery
For above example considering backup for 2 Hours and battery voltage of 12 Volts,( In india for general purpose battery is aviable with 12 Volt)
Size of battery required shall be =(680 X 2 ) / 12 = 113 Ah
As the batteries are available in std size you may now consider next higher size of our requirement may be 120Ah or 150Ah.
If load reduces battery life will increase,
Consider in above case 120 Ah is selected and same is operated with different load then battery backup will increase as below
| Power (Watt) | Battery backup ( Hrs) |
| 680 | 2.1 |
| 500 | 2.9 |
| 300 | 4.8 |
| 200 | 7.2 |
| 100 | 14.4 |
Therefore before selecting inverter, we should work on the power consumption of our house, like
- Tube light should be replaced with LED bulb or LED tubelight.
- Conventional Ceiling fan shall be replaced with BLDC Ceiling fans.
- CFL should be replaced with LED lighting.
This will help us to improve battery backup hours or battery size may be reduced.
Select below link for various inverter technology available for home
