question

Ryan Chambers avatar image
Ryan Chambers asked

250/100 MPPT fire

Hi,

We have had an engineer experience a failure. When this happened only the solar PV was connected to the MPPT. The voltage was being logged and peaked at 197, average 195. The MPPT bulk light flashed slowly for a minute or two then a pop and smoke began to pour out of the unit.


Voltage was in tolerance and polarity correct.


Was the a freak occurrence?


Thanks

Ryan

MPPT ControllersMPPT SmartSolarmppt overvoltage
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Alexandra avatar image
Alexandra answered ·

@Ryan Chambers

And the part in the manual that says to connect the battery first? Section 4.6.

PS - input current limit is also an important number - not just voltage.

So if pv short occured (which could have likely happened with no battery) the mppt wont be able to handle the ISC total. And queue the smoke.

I have installed many of these - even from "problem ranges" with 0 problems.

You SOP needs work. You can check voltages and polarity before the breakers. And wait until battery is switched on before commissioning between the mppt and the breakers and checking charging.

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Ryan Chambers avatar image Ryan Chambers commented ·

Hi,

I have seen this in the install manual and done this originally along with the other 250/100. However the string in question when connected to mppt dragged PV voltage to 0. So we tried a spare 250/100 mppt and voltage was good until failure.



However, if you can’t have the solar PV input only, then what happens when mppt fuse in lynx blows for example? Battery reference will be lost but PV input present so anytime a fuse goes there is a probability of mppt suffering short circuit and catastrophic failure? Seems flawed if that’s the case.



Current and Voc in tolerance. Said string is happy on another 250/100 paralleled with another identical string.


My thoughts are it’s been a bad unit, but just wondered if anyone else had experienced similar.


Thanks

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Alexandra avatar image Alexandra ♦ Ryan Chambers commented ·

If it it the first switch on and commission it is a bit different to a loss of battery during use. For example it is updated and programmed at that point.

There was a range that had an issue with PV short faliure but usually when the system was working not out of the box fail to my knowledge.

Usually in a fully working system if battery reference is lost (programming has been done) there are other places for power to go like the DC bus etc.

What you describe is a pv short condition where the pv voltage is pulled to 0v. It is usually done for protection reasons.

You can still send it for RMA. Not following install procedure wont help the case but be honest. If a defect is found then the post mortem is the only way for it to be known to Victron officially.

The MPPT can handle blown fuses and a battery that disconnects during use. (We once had someone's little nonsense shut off the battery on a system and it ran for days like that - not recommended) I have seen that happen a few times with no ill effects. But it does need to be installed, setup up and programmed correctly in the beginning.


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