# MPPT 250/100 Tr Maximum 390W panels

Obviously a newby here, I have 28 390 W Canadian solar panels and would like to know if I can connect them to my smart solar MPPT 250/100 in 7 strings of 4 connected in series.

The Isc is 10.17 A

Voc 48,2 V

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The maximum string Isc for the 250/100 is 70 A, so 7x strings would exceed that. 6x would be ok.

Consider 4x of those strings into the 250/100, and adding a 250/85 for the other 3x strings. That would be a far better match at charging V's.

I'm all for having extra panels to allow for bad weather, but that's a lot of panels on a single mppt..

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I didnt mention that I also have a SmartSolar MPPT 150/100, could I then say put 4 strings on the 250/100 and 3 on the 150/100?

Hannes Swart

With the 150/ you'd make the strings 3x long and have 4x of them (12 still). Check first on the calculator if that's ok. If not, go 2S6P.

I was trying my luck to get away with using just 1 mppt

Hannes Swart

Yeh, and you have ~200A of panel power at charge V. Don't want that much?, don't install it.. :)

JohnC ♦

Much appreciated, will trade the 150/100 for the 250/85 and put 4x4 and 3x4 on the system

JohnC ♦

Another question maybe a stupid one. I now have 2 x 250/100 MPPT's that I have connected 28 x 390W panels 4 in series and 7 strings, 4 strings to one and 3 to the other. My question is why at peak hours am I only producing 6500W?

I have a Freedom Won 30/24 LifePO4 battery connected as well as a generator on remote start

img-6249.jpg (2.3 MiB)
Hannes Swart

@Hannes Swart

Hard to answer this one. If everything is set up correctly, then it may be just the weather. Only a few weeks away from the winter solstice for you (and me), and the sun always seems feeble at this time. I have laid-flat panels and can't get to half of rated capacity.

Disappointing it is. Just serviced my own two gensets today. Such is winter..

Matthias Lange - DE answered ·

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

An important thing to know is the battery voltage.

The 250/100 can charge the battery with up to 100A -> 1200W at 12V, 2400W at 24V and 4800W at 48V

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

I have a freedom won 30/24 lipo4 battery with a nominal voltage of 52 V, min 47 V, max 56 V