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Battery Backup Calculator
Battery bank sizing, inverter size, and solar recharge for off-grid and backup systems
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Loads to Back Up
WattsHrs/day
Quick-add common loads:
Battery Configuration
Solar Recharge (Optional)
Battery Backup Sizing
Battery Capacity Required
119 Ah
48V system • 80% depth of discharge
Total Load
215W
Daily Energy
4.6 kWh
Total Energy Needed
4.6 kWh
1 day autonomy
Batteries Needed
1 × 200Ah
48V lithium
Inverter Size
1,000W
125% of 215W peak
Notes
Lead-acid batteries should not be discharged below 50% for longevity. Lithium (LiFePO4) can safely go to 80%.
Motor loads (pumps, compressors) have 3-5× starting surge — inverter must handle surge watts.
Wire sizing between batteries and inverter must handle full inverter current at battery voltage.
NEC 706 covers Energy Storage Systems (ESS) installation requirements.
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