Sizing tool
Battery bank sizing calculator
Load, autonomy and temperature in. Amp-hours, derating and a shortlist out.
Most oversized battery banks are not oversized for the load. They are oversized because nobody applied depth of discharge, inverter losses and temperature derating to the same sum. This calculator does all three and shows the working.
Watts drawn when the system is running, averaged over the day
Hours the load actually runs, not 24
How long the bank must carry the load without sun or mains
Lowest expected temperature in the battery compartment
Required capacity
590Ah
48 V · Usable energy 14.2 kWh
Charge current
59 A
Depth of discharge
50%
Temperature factor
× 1.00
500 W × 12 h
6.0 kWh/days
Series that cover this
Matched on chemistry and capacity range from the published datasheets.
How the number is calculated
Ah = (Wh/day × days) / (V × DoD × 0.85 × temp factor)
Ah = (daily Wh × autonomy days) ÷ (system V × depth of discharge × 0.85 × temperature factor). Daily Wh = average load W × hours per day.
Assumptions behind the number
- Inverter and wiring losses are taken at 85%. If your inverter datasheet gives a lower efficiency, raise the result accordingly.
- Depth of discharge is 50% for lead-acid and 80% for LiFePO4. Running deeper shortens cycle life roughly in proportion.
- Capacity derating is about 0.5% per °C below 25 °C. A bank sized at 25 °C and installed at 0 °C delivers roughly 12% less.
Send the load profile and we will check it
Tell us the site, the load and the autonomy required. We reply with a sized string, the series that fits and an FOB price.
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