question

There is not a way to disable the MPPT algorithm.
The Victron MPPT's were never designed to be used with panel MPPT "optimisers". The have been designed to work with native panels or arrays.
It's never advised to have two MPPT's on the same array.
The MG products have most likely been designed to work with each other.

The only way I can think that might help is to limit the lower PV Voltage is to limit the Maximum Charge Current that the MPPT can output. This should have the effect of limiting the lower input Voltage level when the MPPT does a sweep. I have tried this on a turbine, but not with PV, so the results may vary.

Thanks for the quick reply. i have tried many, many ways to limit the lower PV voltage including limiting the max charge current - all without success.

The closest I have come is to insert a 0.2 ohm resistor between the panels and the MPPT - that seems to work while the sun is rising and power is steadily increasing, but it fails as light levels decline - either due to clouds or sun angle late in the day.

Unfortunately the resistor also burns off a fair number of watts at high currents.

The integrated panel MPPT algorithm is pretty smart and maintains max possible power at all illuminations regardless of panel voltage. The SmartSolar algorithm grinds the PV voltage down to the point where the panel eventually cuts out and reboots. The frequent reboots cause output to fall to zero for up to 30 seconds at a time seriously hitting overall production.

Adding a max/min PV voltage setting to the SmartSolar would solve the problem.

Outback Flexmax controllers have this capability, but don't integrate into the Victron ecosystem.

Looks like I'll need to replace the smart panels in the array with dumb ones and let the SmartSolar do it's thing.

Thanks again

Is there any reason not to just use a smart DC-DC charger in this case?

Tried a DC - DC step down converter. The SmartSolar drags the output of that down as well and then the PV voltage follows. The converter really struggles with the fighting MPPT algorithms.

A DC-DC converter/charger should work, but I want to stay in the Victron ecosystem and would need to use something like one of their Orion devices.

But my application needs a device that can support up to a 60V input and deliver a 24V VE.Direct controlled battery charge current on the output side.

To the best of my knowledge, Victron does not offer such a device.

If the SmartSolar MPPT could only be disabled or have restricted range everything would work . . .