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larsea-dk asked

MPPT pv short relay

MPPT, PV input shorted ?

I have two SmartSolar MPPT 250/100 one connected to 2 rows of 4x 395W and the other to 2rows of 5x395w solar panels. The system has been running fine for approx 2years, but one do not start up, blue LED blinks slowly. Voltage on PV input terminales is zero volts, but when connection is opened the solar panels show up to approx 200v in the middle of the day. On closing the switch PV terminals show zero volts. The PV input of the MPPT is in a protection mode - pv short relay.

The mppt is a HQ2211. On early models, the pv short relay reset itself. Victron did introduce a pv short relay on HQ2150, which should be able to be reset manually and the next generation HQ2250 was updated due to a design fault, because the pv short relay between model HQ2150 and HQ2250 wouldn’t reset as expected and simply needs replacing(complete unit)

I now have the one mppt replaced but I worried that my other mppt with same design fault will break after warranty period.

Anyone having experience with these mppt’s with this design fault? Victron dealer could not find the reason for the error, so I am worried and it’s also a very expensive unit.

MPPT SmartSolarsystem designfault
2 |3000

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Alexandra avatar image Alexandra ♦ commented ·


Which one developed the fault? The one with 5 rows or 4?

I have only had one issue with the pre relay 250\100 where it could not be reset (since there was no relay).

With the relay one, depending on what firmware you were running you have to reset the error on a 12v system, so that is also a factor.

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larsea-dk avatar image larsea-dk Alexandra ♦ commented ·

Yes I followed the guide I am linking to, which also mention 12v supply. but eventhough it seems like it softwarewise did reset, the pv was still shorted.

It was the one with 5 panels, but when I calculated Voc and also took temperature into the calculation, I was near 200volts and therefore with enough distance from the 250v barrier.

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larsea-dk avatar image larsea-dk Alexandra ♦ commented ·
I lost contact with the VenusOS when I was not at home, so I could also not see any recording of values.

The system and therefore also the mppts are controlled by bms values, so voltage shouldn’t have been too high.

I did the reset on 12v and just followed the reset guide. It seemed like it did reset, but the relay still shorted the pv inlet.

So, as I read, Victron has found out that the mppt in a certain production series has a design error and this is why I thought that Victron would also exchange my second unit.

What happened on your system? I have thought of perhaps just testing whether my second mppt would reset by set a manual lower max voltage in the mppt setting and turn of bms controlled.

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Alexandra avatar image Alexandra ♦ larsea-dk commented ·

The relay was added to the series after the production 'issue' so the short could be reset instead of mosfet destruction. The idea is to allow some mistakes and prevent landfill. Is yours is from that series?

The real question is why did the protection activate? Were the mppts also programmed correctly? Relying on BMS only is not best practice?

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larsea-dk avatar image larsea-dk Alexandra ♦ commented ·
Victron had access to my VRM but due to it has lost communication to my wifi, it seems to not have tracked any data. They did check my setting and it seemed right as far as I understand.

Victron Service did also react very fast replacing the faulty unit..indeed great service and informative emails also. But I am really not satisfied that they will not change the non-faulty MPPT since it has a design fault and will not let me reset the relay as intended. If the relay short-cuts as intended, I can only throw the unit away and buy a new one...if its beyond the 5 years warranty.

The MPPT's are both set with similar setting and after that reprogrammed to be controlled by settings from the VenusOS (controlled by BMS settings). This I see can't be wrong.

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Alexandra avatar image Alexandra ♦ larsea-dk commented ·

If you are on the newer firmware detection of pv short and recovery has improved alot.

The relay resets. I know I have plenty of them in the field.

Always have the base programming set correctly as well, loss of communication from the system due to unforseen circumstances needs to be catered for.

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larsea-dk avatar image larsea-dk Alexandra ♦ commented ·

I do try to keep everything updated besides the VenusOS software. But I guess the faulty relay in the affected models are not solved by firmware update?

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Alexandra avatar image Alexandra ♦ larsea-dk commented ·
The newer firmware has a better detection and reset mechanism for the pv short and trigger conditions.
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offroadflow avatar image offroadflow commented ·
About a year ago a 250/100 of a friend suddenly stopped charging. Took me a long time to get an actual replacement after really having to fight for it.

I was seen as an imbecile even from headquarters.

Made me think about the actual service from Victron. Wont forget that one ..

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larsea-dk avatar image larsea-dk offroadflow commented ·


Yes I also expected better service from such an expensive product. I'm glad that Victron have identified, that the product has a fault...just seems not acceptable that they will not change a unit that actually do not work as intended just because it has not broken yet.

If the relay shuts for a reason, I cannot reset the relay as intended...due to a design fault. This should be exchanged by Victron to a new unit that do not have this fault.

I did before recommend Victron products also due to this community and the many possibilities, but this is quite a set-back.

I do have to add, that the exchange of the faulty unit was very quick and easy.

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