New mppt 250/60 short circuit PV input

Q&A and troubleshooting
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1

Installing a new mppt 250/60 alongside two existing 250/100s (less panels on the new array) all seems well in the PV installation 138V arriving at mppt terminal lugs but the mppt is off and appears to be shorting the PV inputs - arcing during connecton and mppt reading 0V when connected…

I had this once with a 250/100 and had to do a 12v short protection reset but (despite similar behaviour) the 250/60, according to Victron, doesn’t have this protection built in… so I’m at a loss for how to get it into the ‘on’ state..

2

Check your polarity.

Does victron connect give a reason for the off status?

3

You could go through the pre-RMA test to check the device:

As LX mentioned check the PV polarity, a reverse polarity is like a short circuit.

1 Like
4

Thanks, No reason given, just the usual loose cable or fuse etc… none of which are the problem …

5

Polarity is correct.

6

I like your test sheet though :slight_smile: I’ll work my way through it and let you know….

Ps I did a continuity test with the multimeter between the PV input terminals and it is not reading a short circuit … it’s just behaving like there is one… see first post

7

that looks like a reversed polarity. There is no short circuit , but the mosfet’s diodes short the input if polarity in reversed.