question

mops avatar image
mops asked

Victron 150/35 mppt controller on 4000W array ??

I have a Victron 150/35 mppt controller

According to the data sheet for this controller

Max allowable Voc = 150V , Max Scc = 40A "Nominal " power @ 48V = 2000W

Meaning you could essentially throw 6000W at it if you could find a way to configure your panels so the array does not exceed the Voc and Scc as the fine print at the bottom of the data sheet says " controller will limit input power " .

Anyway. I have 12 x 330W panels and 48v Lithium Battery

Panel specs Voc = 40V, Scc = 8.8A

I wish to wire them as follows , 4 strings with 3 panels in series per string , and the 4 strings paralleled into the controller .

This will bring. total Voc of the array to 120V and, total Scc to 36A at its max.

These figures are below the specs for max input limits for the controller, however , this means the array will be producing around 4000W at maximum power in full sun which is double the nominal power stated , but will be running at nominal power or less in morning, afternoon and overcast days which is what I'm aiming for without having to install a second controller , panels are cheap !!

What exactly does "nominal " mean in this scenario ?

To simplify my question. will this arrangement be ok or will I cook my controller in full sun when the power peaks ?

I have read through other threads on this topic but can not seem to find a definitive answer .

MPPT Controllers
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3 Answers
JohnC avatar image
JohnC answered ·

@Mops

The 'Nominal' max power is the rated output (35A) at a typical Absorb V. It's roughish and usually rounded a bit, but here it back-calculates to ~57V. One of those things you may only see happen once a day for a very short while, as once Vabs is reached the current usually backs off.

When the 35A is reached, or the mpptp backs off, all that happens is the mppt stops tracking. The panel V will rise above Vmp, all the way to Voc if current reached zero. The panels just don't harvest the power.

All by design. And would still be ok even into 12V batts with a 500W nominal.

Just string your panels within the Voc and Isc limits of that mppt, and all is good.

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nickdb avatar image
nickdb answered ·

Use the MPPT calculator. It isn't just about power, you also can't exceed Isc (40A limit), and if you grossly oversize the array that is likely.

https://www.victronenergy.com/mppt-calculator

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mops avatar image
mops answered ·

Thanks , that is very helpful, and what I was hoping for and half expecting ! Just needed confirmation before I let the smoke out ;-)

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