question

Jaco De Jongh avatar image
Jaco De Jongh asked

150/?? Absolute max VOC!

Please can someone from Victron answer this question?

Currently so many people on the internet thinks that if you exceed the 150Volt rating even through cloud edge effect for a limited time, that the mppt components will just Blow/Fail..

Certainly the design should have some kind of safety factor for the rare occasions that the volts might exceed 150 volts... I mean which other company in the world would advertise a product for 150volt rating if it will blow at 151Volt... it just dont make sense and I am trying to put an end to this paranoia...


Please can Victron shed some light on this.


I acknowledge that no-one should ever design the system for over 150 volts, but on the other hand I am also sure that Victron knows this could happen occasionally and thought of this in their design...


EDIT: I have been in the electrical field for 30 years and has never ever came across any electrical equipment that blows up if you exceed the advertised Specs by 1 or 2 or even 5 volts. (Excluding board level electronic components).

MPPT Controllers
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

4 Answers
Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hi @Jaco De Jongh

The specification listed is the one that we are certain of, in all units, and will provide warranty for.

There is no additional built in margin available beyond the listed maximum PV input voltage limit on the MPPT.

That isn't to say that every unit will fail every time that voltage is exceeded, but some will, so it should be strictly avoided.

There is a tolerance in the components, and some firmware protection to shut off the MPPT and return a fault code, but both should not be considered that they will save the MPPT connected to a PV array that is out of that maximum voltage spec.

Instead the system designer needs to consider the panels (which sometimes under-spec and over perform by +5%), and temperature (panels produce higher voltage in colder temperatures). Then leave themselves plenty of head room (10%+) so that the system is not pushing the specified limits.

I'd personally rather people be a bit paranoid about this one spec in particular, than lax about it thinking they have some extra up their sleeve.

It does destroy MPPTs, and in almost all cases it's avoidable, so that's an unnecessary hassle and waste for everyone.

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Jaco De Jongh avatar image
Jaco De Jongh answered ·

It would be the first time in my Life I see someone advertise a product's specifications to be exactly the same as the Max rating of the components within it. Sad though, but I accept your answer..

Thanks Guy..

1 comment
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Guy Stewart (Victron Community Manager) avatar image Guy Stewart (Victron Community Manager) ♦♦ commented ·

As an anecdote, I once inspected a system where an MPPT would regularly shut itself down with error 33 during the colder times of the year.


It turned out that was incorrectly installed with 3 parallel strings of 4 x Trina 280W panels in series instead of 4 strings of 3 series panels as per the design.


The 25 degree celsius open circuit voltage spec for those panels is 38.4 degrees, so that was putting out 153V minimum, and possibly a lot more at times as the temperatures dropped.


But it didn't fail, and once the panels were rewired into 3 panel strings, the system returned to normal production, apparently no harm done - except 2 extra site visits, another trip up the roof, a few months of very poor system performance and under charged batteries when they need it most, and probably some electrical stress.


I consider that a close call, and it could have just as easily been a replacement MPPT, but if it helps your point with a real world example. If it was installed correctly in the first place it would have been a much better experience all around.

0 Likes 0 ·
rslifkin avatar image
rslifkin answered ·

I'm sure there's some safety factor in there for unforseen conditions, etc. But at the same time, I'd personally want to design such that you don't exceed the 150v rating under any foreseeable conditions, otherwise you'd be knowingly eroding the safety factor and leaving less for any conditions you can't account for.

1 comment
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

kevgermany avatar image kevgermany ♦♦ commented ·
Agree with you and Guy. But there are plenty of people who want to chance it.
0 Likes 0 ·
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

An easy solution would be to rename and change the datasheet to 140/XX and surprise you have a safety margin of 10V. Hehe.

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.