# Battery capacity sizing calculation for solar and inverter system

All QuestionsCategory: Power and EnergyBattery capacity sizing calculation for solar and inverter system

Battery sizing for a house that uses
1) 10 watt LED bulb used 4hours per day
2) 70 watt fan used for 2hours per day
3) 75 watt refrigerator that runs 12hours and off 12hours
total appliances used= (10w x 4hours) + (70w x 2hours) + (75w x 12hours)
nominal battery voltage= 12V
days of autonomy = 2days
my question is how do you arrive at your answer which you give as “ Total Ampere-hour require as 352.94 approx 400Ah”?

because in my own calculations,
Ampere-hours = watt-hour/ volt
390        = 4680/12
390Ah that’s my own answer using required 195W at 24hour

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Thanks
Battery are rated in Ah
When calculating batteries capacity we advice u round up.
And u can’t get 390Ah from Any battery connection in parallel as your system voltage is 12Vdc
So is either you parrallel 2 12V/200Ah battery to give 12/400Ah or 2, 12/ 150Ah battery to give your 300AH which is less than 390Ah Required.
Thanks