question

kaarthik avatar image
kaarthik asked

pv input shorted

i have 100/20 controller which is not give any charging output when i connect with pv input. Then i was use power supply in pv terminal it gives zero voltage and current max, which means pv terminal shorted.

controller was working for more then 20days this is happens on 21st day.

i have checked in victron connect pv input max voltage is 95volt , pv max power is 270W.

What is the cause of short circuit in pv side. we face a lot of issue like this specially on 250volt MPPT.

MPPT SmartSolar
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Alexandra avatar image Alexandra ♦ commented ·

@kaarthik

I have also seen the pv short error when the battery has a voltage too high or it shut down.

https://www.victronenergy.com/live/mppt-error-codes#err_38_err_39_-_pv_input_shutdown

You do not mention the error number so I took a guess.

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3 Answers
klim8skeptic avatar image
klim8skeptic answered ·

The usual cause for a short on the Mppt's PV input, is reverse polarity connection. Please confirm correct input polarity.

"we face a lot of issue like this specially on 250volt MPPT. " None of your previous questions relate to a 250v input Mppt. Who is we????

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kaarthik avatar image kaarthik commented ·

Thanks for your answer,

As i told before its working past 20 days, so there is no cause because of reverse polarity .If its reverse polarity it should happens first day.

But i already checked polarity all correct.

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marc-de-montreal avatar image
marc-de-montreal answered ·

hi, you have suspected a short at the input PV after 21 days where the controller was good and since is bad.. you have tested your input PV with a power supply trying to isolate PV or Mppt is failing and with your supply connected to PV input, the voltage fall to zero and current rise to max.. you know how to plug it (right polarity).. your check is a good way to isolate what is wrong..

you can to do those checks with a cheap digital multimeter (all wires disconnected.. so, no PV, no batt, no load connected).. short the input PV to avoid any voltage (as a charged capacitor) and do a continuity check between + and - of the PV input (red wire of DMM on + and black on -) and check if the DMM buz (or beep) and still beeping, the buzzer/coutinuity should be at 2000ohms scale.. if yes (the DMM buz and still buz.. not a buzuiiiii and nothing by a capacitor charging), go to minimal ohm scale (around 200 ohms scale) and check the value read (short PV input again before).. it’s not usual to read a value at this scale and in case of a reading < 5 ohms (wait few seconds to see if the value is rising by a capacitor), that look a dead short (check your connections if anything around can cause this).. if no short found with DMM but look short only when you apply your power supply (all normally connected, battery first), start your supply voltage at 0v and rise slowly until the voltage drop to zero (record this voltage trig point) and come back here with this value (i’m curious).. than may a voltage too high for your mppt (if ever > 100v in your case), a semiconductor or capacitor leakage triggering at this voltage value.. if you see a short with DMM (and contacts are clean), that may input capacitor or input mosfet or thermal isolation (of Mosfets) shorted.. in all of those cases (if less than 100v input) your mppt look dead and need to be returned or repaired.. i’m curious if it’s not a short but have a voltage trig level.. any supplemental details/data can help to find the problem..

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dingaling avatar image dingaling commented ·
Thanks for this diagnoses info. Ill be checking my 100/50mppt which I've accidently bridged my PV input while it was connected to the battery. Created a large large spark and stopped charging. So i can only think the Battery negative and PV negative share the same ground? which i bridged across to the PV +, probably a huge amount of battery current fried a mosfet on the PV side.
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michelg avatar image
michelg answered ·

Hi, seems that during 20 days the weather was not cold enough, and you were getting around 95VDC from the panels, but on the 21st day, if it has been a change in the weather, and getting a lower temperature, this could lead to have the panels producing more than 100VDC and destroying the MPPT. Amps can be managed, but voltage is a dead-end.

I think your MPPT is damaged by an over-voltage input from the PVs.

Michel

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marc-de-montreal avatar image marc-de-montreal commented ·

hi.. yes.. according to victron info, the voltage deviation is +0.34%/C under 25c.. that mean for 95voc at 25c = 0.323v/C or +5v if the PV in series are around 10c (15c colder x 0.323v/C = 4.85v).. always keep the extreme colder situation in your calculations.. me i never go over 80% of spec limits for to avoid any damages by stress..

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kaarthik avatar image kaarthik marc-de-montreal commented ·

Noted thanks

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