Controller Type
MPPT (Maximum Power Point Tracking) controllers are more efficient (93-99%) and can accept higher input voltages, converting excess voltage to additional charging current. Ideal for most solar installations.
Solar Panel Specifications
Wiring Configuration
Total Panels: 4 (4 in series × 1 in parallel)
Battery & Temperature
Controller Requirements
Array Summary
MPPT efficiency typically 93-99%. Expected charge current: 33.3A at 48V.
Suggested controller: 250V/40A or higher.
Understanding Charge Controller Sizing
MPPT vs PWM
MPPT controllers actively track the maximum power point of your solar array, converting higher panel voltage to optimal charging current. This allows flexibility in panel selection and typically yields 10-30% more power compared to PWM.
PWM controllers directly connect panels to batteries, requiring panel voltage to roughly match battery voltage. They're simpler and cheaper but less efficient.
Key Formulas
For MPPT:
- Min Voltage Rating = Array Voc × (1 + temp_coefficient × (lowest_temp - 25°C)) × 1.25
- Min Current Rating = (Total Array Watts / Battery Voltage) × 1.25
For PWM:
- Min Voltage Rating = Array Voc (panels must match battery voltage)
- Min Current Rating = Total Isc × 1.25
Cold Weather Considerations
Solar panel voltage increases in cold weather. A typical temperature coefficient of -0.3%/°C means that at -10°C (compared to 25°C standard test conditions), Voc increases by about 10%. Always size your controller for the coldest expected temperature.
