Deepak Waghmare
Branch Unspecified
07 Nov 2016

# SOLAR BATTERY SIZING

Hi guys,
Can any one tell me how the battery sizing is calculated.
Suppose i have to give 20KW backup for 10 min. then how many battery's should be required?
07 Nov 2016
More data may be needed. If the battery is drained for ten minutes at 20 KW, how long is it idle after that ten minutes?
It is ideal to have the minimum sized battery that can do the job.
Look at these:
Sizing Battery Banks
One more:
Charles-Augustin de Coulomb's C-Rate for Batteries

For the data given the back up power will be about 3.2 KWHr. (delivered in ten minutes). As a ball park number the discharge efficiency will be about 33% assuming the battery is draining at 5 C amps (C is the unitless number of amphr capacity. e.g., for 100 amp hr battery C=100). So the battery pack power will be 3.3x3 = approx. 10KWHr for a one hour rate. Assuming 48 V as the design voltage, this translates to a 200 amp hour battery pack at 48 V.
This is an off the cuff calculation.

Deepak Waghmare

Branch Unspecified
07 Nov 2016
THANK YOU VERY MUCH SIR FOR YOUR GUIDANCE....NOW SEEING MORE CLEAR PICTURE.
A.V.Ramani
More data may be needed. If the battery is drained for ten minutes at 20 KW, how long is it idle after that ten minutes?
It is ideal to have the minimum sized battery that can do the job.
Look at these:
Sizing Battery Banks
One more:
Charles-Augustin de Coulomb's C-Rate for Batteries

For the data given the back up power will be about 3.2 KWHr. (delivered in ten minutes). As a ball park number the discharge efficiency will be about 33% assuming the battery is draining at 5 C amps (C is the unitless number of amphr capacity. e.g., for 100 amp hr battery C=100). So the battery pack power will be 3.3x3 = approx. 10KWHr for a one hour rate. Assuming 48 V as the design voltage, this translates to a 200 amp hour battery pack at 48 V.
This is an off the cuff calculation.