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Hi Katoom. Reverse pv polarity would likely do that. Check it with a multimeter as close as you can to the mppt.

Thanks for responding, JohnC. You got me thinking, including whether my multimeter leads were swapped. Unfortunately, that's not it. The negative side of the PV array is definitely in the PV- terminal of the controller directly from the building bulkhead entrance. The positive side runs directly (18-24") to a breaker and then another 12-15" to the controller. Same situation today: Voc between the hot side of the breaker and controller PV- at the breaker until it's closed, then 0.2 VDC between both sides both at the bulkhead entrance and between controller PV+ and PV-.

I'm going to bypass the breaker tonight and see what happens tomorrow. 600w shorted at the breaker ought to be showing some signs, though - like smoke!

Can you please take some photos?

You should be able to see the MPPT in VictronConnect from the battery voltage connection regardless of the PV.

I just tried a Bluetooth scan from a Windows computer nearby. No show.

First photo is of controller and breaker box. I managed to catch the blue flash. "IN" breaker is connected between the PV bulkhead entrance and controller. Red wire in the foreground is from the "OUT" breaker to the battery. Battery, "Battery -", and load negative are connected at the bus bar.

Second photo below is showing voltage reading at the PV terminals with breaker closed (breaker nearest to the controller).

Third photo below is showing the same reading with positive lead at the bulkhead entrance; negative lead (not shown) is still at the controller PV- terminal. The big fuse in the foreground goes to the load. Sorry for the clutter; it's behind the batteries.

Finally photo below is with PV breaker open, multimeter leads at the bulkhead entrance. Same voltage show at the breaker (hot side).

Hi, I’m actually having the exact same issue with one of my 150/70 MPPT controllers, randomly after a year of seamless operation. The other controller I have in parallel is working fine. I noticed that the resistance between the input on the good controller is around 1Mohm, whereas the resistance on the faulty one is about 4ohms.
I’m not sure what this means, but it seems like something internal may have shorted out. I haven’t got to the bottom of it yet, but I’ll let you know if I figure anything more out.

@KatoomRXC, it's worth noting that a Windows computer cannot connect with a Smart anything over BT... in a very simplified explanation, the laptop/desktop BT protocols are different than the mobile BT protocols used by Victron Smart devices. BT connection to these devices is only possible using a smartphone or tablet.

To connect to the device on a computer, you will need the VE.Direct to USB Interface... but that should be unnecessary as long as you have your phone or tablet handy.