If we look at a datasheet for a solar charge controller we can find many different voltages.
- minimum input voltage or start up voltage
- PV input voltage
- MPPT voltage range
But what are they, and what do they mean?
This article aims to bring clarity to that.
Nominal DC Volt/Max DC voltage
Nominal means that the MPPT will be the most efficient at this voltage level (360VDC).
The maximum voltage will be 500VDC. If you exceed this voltage, the charge controller will be damaged.
Max input voltage = Voc * panels in series * 1.25
Why do we need the additional 1.25 safety factor?
Because a solar panel will measure more than the Voc on a sunny cold day.
If you didn’t include the safety factor, the charge controller will get damaged on a cold sunny day.
This is the voltage at which the MPPT will start working (120VDC). If the voltage is below this level, the MPPT will not put power into the battery.
MPPT voltage range
The MPPT will operate between these values (120VDC-450VDC). The MPPT will not deliver power to the batteries when the voltage is out of this range.
What is the minimum input voltage for MPPT solar charge controller?
The minimum input voltage should be at least 5 volts over your battery voltage.
If the voltage is not high enough, the charge controller will not start.
What is PV input voltage?
This is a voltage range in which the MPPT works the most efficiently.
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