Solar Battery Bank Calculator
Battery capacity in amp-hours for a daily consumption and a chosen number of cloudy days.
Results
Battery capacity
156
Ah
Energy
7.50
kWh
Energy
6.00
kWh
What this tool does
The depth of discharge is what separates the capacity you buy from the capacity you can use: lead-acid lasts far longer if you only take 50 %, while lithium tolerates 80–90 %. Days of autonomy is how many days without sun the bank must cover on its own.
Formula
Ah = daily energy × days ÷ (voltage × discharge depth)
Variables
| Symbol | Meaning | Unit |
|---|---|---|
ed | Daily energy use | kWh/d |
d | Days of autonomy | — |
u | Voltage | V |
dod | Usable depth of discharge | % |
AH | Battery capacity | Ah |
KW | Energy | kWh |
US | Energy | kWh |
Worked example
- Daily energy use3 kWh/d
- Days of autonomy2
- Voltage48 V
- Usable depth of discharge80 %
- Battery capacity156 Ah
- Energy7.50 kWh
- Energy6.00 kWh
Limitations
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.
- Electrical installations are governed by national wiring rules. Cable sizing also depends on installation method, grouping, ambient temperature and protection devices, which this calculator does not evaluate.
- For work that must comply with a standard or be signed off, check the result against the applicable code and have it reviewed by a qualified engineer.