Solar Battery Sizing Calculator

Calculate battery storage capacity needed for solar backup.

Daily Energy Usage

kWh

Backup Duration

hours

Depth of Discharge

Battery Voltage

Inverter Efficiency

Tab to move between fields

Required Capacity

19.5 kWh

≈ 20 loads of laundry

Required Amp-Hours

407 Ah

Backup Energy Needed15 kWh

13.5 kWh Batteries Needed2

How to Use This Calculator

Enter your daily energy consumption in kWh.
Set the number of backup days desired during a grid outage.
Input the battery depth of discharge (DoD) — typically 80–90% for lithium batteries.
Enter your solar generation in kWh/day to account for partial solar recharge.
Review the recommended battery capacity in kWh and the number of battery units required.

How the result changes with Daily Energy Usage

Daily Energy Usage: Average daily electricity consumption in kWh.
Backup Duration: Number of hours of backup power needed.
Depth of Discharge: Maximum safe discharge percentage for battery chemistry.
Battery Voltage: Nominal battery system voltage.
Inverter Efficiency: Inverter conversion efficiency.

Identify Input Parameters
4 parameters
Daily Energy Usage = 30, Backup Duration = 12, Depth of Discharge = 80, Battery Voltage = 48 = 5 input(s) provided
Calculate Required Capacity
Required Capacity
19.5 = 19.5
Calculate Required Amp-Hours
Required Amp-Hours
407 = 407
Calculate Backup Energy Needed
Backup Energy Needed
15 = 15
Calculate 13.5 kWh Batteries Needed
13.5 kWh Batteries Needed
2 = 2