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twinkle avatar image
twinkle asked

Is negative solar charge current normal at dusk?

I have a smartsolar 100/20 and the last couple of nights the current supply has gone negative for about an hour at dusk where the charger is still in bulk mode and hasn't turned off yet.


screenshot-20210928-212303.png


Is this behaviour normal or an indication of a fault somewhere?

charger
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2 Answers
Steve Preston avatar image
Steve Preston answered ·

If there is anything connected to the load output of that MPPT, if so, it will show as a negative. I have a thermostatic controller powered by the load output that energizers a fan to help cool my 100|20 when it is outputting near maximum amperage. At dusk it takes time to cool the MPPT heatsink down below my set point after the MPPT has turned off, and that shows as a negative while the fan is still energized.

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twinkle avatar image twinkle commented ·
The load output is off with nothing connected
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paulcooper answered ·

My MPPT RS does the same. I assume it is power to the device's own electronics before it decides to switch off for the night.

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twinkle avatar image twinkle commented ·
But this doesn't happen every night
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