Solar Batteries3 min read0 views
How to Size a Lithium Battery Bank for Load-Shedding in 2026
A simple kWh calculation that matches your battery bank to real outage hours — so you never buy too little or overpay for capacity you'll never cycle.
BySolarBazaar Team
A simple kWh calculation that matches your battery bank to real outage hours — so you never buy too little or overpay for capacity you'll never cycle.
## The one formula you need
Battery size (kWh) = (average backup load in kW × backup hours) ÷ depth of discharge. For lithium, use 0.9 for depth of discharge; for lead-acid, 0.5.
## Worked example
1. Backup load: 0.8 kW (fans, lights, router,
TV).
2. Required backup: 4 hours per outage.
3. Energy needed: 0.8 × 4 = 3.2 kWh.
4. Lithium bank: 3.2 ÷ 0.9 ≈ 3.6 kWh usable — round to a 5 kWh unit for headroom.
## Don't forget the inverter
Your inverter's continuous rating must cover the peak load, and its charge current must be able to refill the bank between outages. A big battery behind a weak inverter is money left on the table.
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