At 12 V, every kWh of storage is 83.3 Ah. 12 V suits vans, cabins and small loads.
How it works
Ah = daily kWh × days × 1,000 ÷ (volts × depth of discharge × efficiency). Batteries in series = system volts ÷ battery volts.
Example: 2 kWh a day for 2 days at 12 V and 80% depth of discharge needs 463 Ah (5.6 kWh).
At a glance
Same settings as the calculator, changing only the daily use.
| Daily use | Bank | Nominal | Solar array |
|---|---|---|---|
| 0.5 kWh | 116 Ah at 12 V | 1.4 kWh | 0.13 kW |
| 1 kWh | 231 Ah at 12 V | 2.8 kWh | 0.27 kW |
| 2 kWh | 463 Ah at 12 V | 5.6 kWh | 0.53 kW |
| 3 kWh | 694 Ah at 12 V | 8.3 kWh | 0.80 kW |
| 4 kWh | 926 Ah at 12 V | 11.1 kWh | 1.07 kW |
Common questions
What voltage should an off-grid system use?
12 V for small loads, 24 V for mid-size systems and 48 V for whole homes. Higher voltage means lower current and thinner cables.
How many days of storage do I need?
Two to three days is common where cloudy spells are short. A backup generator lets you use fewer.
Sources
- NREL PVWatts v8 (20° tilt, south-facing, 14% losses), state results compiled by TheGreenWatt: https://thegreenwatt.com/average-peak-sun-hours-by-state/