1. Enter your daily amp-hour requirement ( Appliance etc.. amp-hour usage)
2. Enter the maximum number of consecutive cloudy weather days expected in your area, or the number of days of autonomy you would like your system to support
3. Multiply the amp-hour requirement by the number of days (line 1 x line 2). This is the amount of amp-hours your system will need to store.
- Enter the depth of discharge for the battery bank you have chosen. This provides a safety factor so that
you can avoid over-draining your battery bank. (Example: if the discharge limit is 20%, use 0.2.)
This number should not exceed 0.8.
5. Divide line 3 by line 4
6. Select the multiplier below that corresponds to the average wintertime ambient temperature.
7. Multiply line 5 by line 6. This calculation ensures that your battery bank will have enough capacity to overcome cold weather effects. This number represents the total battery capacity you will need.
8. Enter the amp-hour rating for the battery you have chosen.
9. Divide the total battery capacity by the battery amp-hour rating and round off to the next highest number. This is the number of batteries wired in parallel required.
10. Divide the nominal system voltage (12V, 24V, or 48V) by the battery voltage and round off to the next highest number. This is the number of batteries wired in series.
11. Multiply line 9 by line 10. This is the total number of batteries required.
Battery Temperature Multiplier
80°F/26.7°C
70°F/21.2°C
60°F/15.6°C
50°F/10.0°C
40°F/4.4° C
30°F/-1.1°C
20°F/-6.7°C
Battery Sizing Worksheet
1.00
1.04
1.11
1.19
1.30
1.40
1.59
