Victron RS 450/100 overloading the charge controllers?

[sarahstaar]

Would like clarification on something ....

Currently I'm using 2 Victron SmartSolar MPPT RS 450/100 solar charge controllers...

Currently I have connected 4 strings of solar panels.

8 panels in series

8S = 336V/10A

In reality a very rarely gets to 10A it's usually 9.5A I think I've only ever seen 10A once very briefly.

I would like to connect up 16 more panels so I need to reconfigure things but would like to know if I will be overloading the charge controllers or not.

I'm thinking of putting two of the strings in parallel,

So each string on the charge controller would have 16 panels connected,

2 sets of eight panels in series then each set parallel together.

Below is an image of my solar panel specifications

Would I be overloading things or do you think I be better off buying another charge controller??

Any help would be much appreciated thanks.

 

[ricardocello]

According to the data sheet, max Isc is 20A, so you would be on the edge of that, very unfortunate.

So we are back to the “What happens if I exceed Isc rating?” question again.
Is it just reverse polarity protection that blows? Or are there other reasons?
Let’s see what the other Victron smurfs say…

 

[sarahstaar]

It's very confusing in the manual it says the maximum is 18A?

But then written on the cover of the charge controller box it says maximum input current per string is 20 A?

See photos below

 

[Solar Guppy]

You are already above the maximum rated power on the output side with 6800 watts for each controller, adding more panels would flatten the power curve a little, but not add that much daily yield. the 20 amps is a never exceed value as well.

 

[ricardocello]

It's very confusing in the manual it says the maximum is 18A?

But then written on the cover of the charge controller box it says maximum input current per string is 20 A?

See photos below

It can only use 18A.
You are allowed to connect panels rated up to 20A Isc.
But it will only use 18A.

 

[Brucey]

You are already above the maximum rated power on the output side with 6800 watts for each controller, adding more panels would flatten the power curve a little, but not add that much daily yield. the 20 amps is a never exceed value as well.

The 20A never exceed is only for the reverse polarity protection. You can exceed that as long as you hook up correctly. It mentions that in the manual screenshot above:



I've been thinking of doing the same on my 450/100, adding a second string in parallel to each tracker. Purely for maximizing winter production.

 

[sarahstaar]

I think getting another charge controller is the way to go...

Because in winter on a sunny day the days are much shorter so it's good to maximise solar production.

For instance today we've only had about two hours of solar and the rest of the day has been cloudy.

So for times like this I think it would be best to maximise solar capacity for those short sunny bursts we might have ...

 

[Brucey]

I think getting another charge controller is the way to go...

Because in winter on a sunny day the days are much shorter so it's good to maximise solar production.

For instance today we've only had about two hours of solar and the rest of the day has been cloudy.

So for times like this I think it would be best to maximise solar capacity for those short sunny bursts we might have ...

By overpanelling with parallel strings he'll get decent output overall without relying on rare direct sun times. Yes he'll be limited to about 105A during direct sun but for overcast days he prob won't approach that.

 

[Solar Guppy]

By overpanelling with parallel strings he'll get decent output overall without relying on rare direct sun times. Yes he'll be limited to about 105A during direct sun but for overcast days he prob won't approach that.

The OP already has exceeded the output power of ~5800 watts ( battery voltage at 100 amps with 6400+ watts of PV already attached ), adding PV to this maxed out controller is not the best $$ watt option, adding another charge controller would be what I would recommended.

 

[Brucey]

The OP already has exceeded the output power of ~5800 watts ( battery voltage at 100 amps with 6400+ watts of PV already attached ), adding PV to this maxed out controller is not the best $$ watt option, adding another charge controller would be what I would recommended.

Yes if he has an extra $1100 to spend he could get a third 450/100. But if 200A is sufficient charge power, he could still significantly increase daily production by overpanelling on his existing 450/100s, for no extra expense.

Edited to reflect two existing 450/100s.

 

[Brucey]

I'd suggest adding the parallel strings, see what the additional output is like, then add a third 450/100 if you find you are still limited on daily production. Cost would just be a few Y cables.