Same controllers different outputs

I have 2 solar controllers 100/30. Each have same 400 watt panels in same configuration. Same PV (voltage) input to both controllers BUT one putting out twice the wattage/amperage then the other. Nothing changes when I apply a load to the system. Both are configured the same.

I'm missing something. Any help would be greatly appreciated.

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dognose commented · Jul 22 at 04:56 PM

From the provided details, hard to guess the rest. You should add more details (details!) About your installation.

How are they connected to what? What cable diameters and lengths? Any fuses, shunts or breakers which might cause significant resistance? Are the panels same age, same orientation?

What happens, if you exchange the panel connections? Is it the same MPPT producing less, or does it switch?

What is the panel manufacturer / model?

Does the "lazy" Mppt raise production, if yoo disconnect the stronger one? (Or disconnect it's panel)

Also, generally: Assuming a panal is ~ 30V, that is very less voltage for a single mppt. Why didnt you use a single one and two panels connected as series?

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