How this calculator works
1. The calculator first computes the Total Power, Open Circuit Voltage, Max Charge Current and Short Circuit Current of the solar array:
PMAX x Number of Panels
VOC x Number of Panels in Series x T°FACTOR
TOTAL POWER ÷ Battery Charge Voltage
ISC x Number of Panels in Parallel
- PMAX, VOC, ISC: User inputs
- Number of Panels: Total number of panels
- Battery Charge Voltage: 14.7V for 12V battery bank, 29.4V for 24V battery bank
- T°FACTOR: Temperature correction factor for -13F (-25C) per NPFA70® NEC® Table 690.7(A):
2. The calculator filters MPPT solar charge controllers compatible with your Battery Bank Voltage (12V or 24V).
3. The calculator selects a MPPT solar charge controller rated for both the array's OPEN CIRCUIT VOLTAGE and MAX CHARGE CURRENT.*
* Any solar charge controller rated higher than OPEN CIRCUIT VOLTAGE and MAX CHARGE CURRENT would be acceptable, but the calculator displays the closest match.
4. At last, the calculator makes sure that the solar charge controller is rated for the array's Short Circuit Current (Per Victron's Datasheets).