Inverter and battery for home use

Attention: open in a new window. PDFPrintE-mail

Here is a simple calculator to calculate the required capacity of battery and home inverter. Just enter the number of home appliances required and the number of hours of hours of operation required after power cut. Press Calculate capacity to see typical capacity. Note that this calculation is just for an overview. For actual sizing consult a professional.



Number of fans
Number of tubelights
Number of CFT lamps
Number of filament bulbs
Number of computers
Number of TV
Number of hours of operation required after power cut
Voltage rating of the battery



Inverter capacity= Volt Amperes (VA)

Battery Capacity=

Ampere hours (A-hr)


To understand more on the technicalities, read further.


Basics of home inverter:


A home inverter system has two components, the inverter and the battery. When power is available, the inverter converts AC current into DC and stores in the battery. When power goes off, the inverter automatically senses it, takes DC current from the battery, converts it into AC and feeds the home appliances.


Choosing the battery:


You need to first decide two things:

  • What are the home appliances that you need to operate during a power cut ?

  • How long do you need to operate them?

Each appliance will have a rated power mentioned in WATTS (W). Add up all the power for all appliances in watts. From the wattage, the required current for the battery can be calculated. Now, multiply the current in amperes with the number of hours you require to operate the appliances after a power cut. The battery capacity is mentioned in terms of Ampere-hours. Battery capacity has to be selected with at least 20% extra capacity to account for calculation inaccuracies and other uncertainties. [The above calculator account for 20% extra already]


Choosing the inverter:


Inverter does not store energy. It simply does conversion from AC to DC and vice versa. Hence inverter rating simply depends on the load (the home appliances) connected to it. As was done in the case of battery selection, find the total wattage required. Divide by 0.8 to get VA (Voltage Ampere) requirement. Inverters are specified in terms of VA.

Inverter capacity has to be selected with at least 20% extra capacity to account for calculation inaccuracies and other uncertainties. [The above calculator account for 20% extra already]


Summary:

Batteries are specified in Ampere hours (A-hr)

Inverters are specified in Voltage Amperes (VA)

If you know the watts consumed by each domestic appliance and the number of hours of operation required during a power cut, an idea of battery and inverter size (capacity) can be readily got by using the above calculator.