question

david-chops avatar image
david-chops asked

I have a 100/50 and Some panels. Can I wire them up this way?

I may have made a mistake with my purchases.

Here is what I am working with:

10 x mono solar panels

  • Rated Power: 375W
  • Open circuit voltage (VOC): 48.16 V
  • Max power voltage (VMP): 39.76 V
  • Short circuit current (ISC): 9.83 A
  • Max power current: 9.43
  • Maximum system voltage: 1500V UL certified

They will be installed in northern Ontario. So its cold. most extreme would be -40c (-40f) cold rarely.

I also have a Victron 100/50 smart

I am planning on 24v battery bank

So, my original plan was to lay out my array by putting 5 sets in parallel of 2 each panels in series

My math got me to (48.16V x2) 96.32voc and (9.43A x5) 47.15 amp just barely sneaking in under the 100/50

But now I am second guessing that because its cold where I am going so its going to produce way more than I am calculating?

I am ok with not maxing out what these panels can collect on a sunny day. I bought the amount of panels I did to max out low light days. (more collection area was my thinking) The battery bank will be relatively small and the whole system will be off grid.

How many panels can I get away with connecting to this 100/50?

MPPT Controllers
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1 Answer
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

The first number is the maximum PV voltage at the input and the second number is the charge current into your battery.

So let's say your battery absorption voltage is 28V x 50A = 1400W charging power.
With your panels you have more than twice the power.

If it gets cold the Voc rises so you will extent the max. voltage of 100V if you connect two in series.
This can damage the MPPT

To use all the panels you have in a 2S5P configuarion you will need a MPPT 150/100.

Edit:
@David Chops

Your planed setup:

With your 100/50 you can connect 3 of those panels in parallel and you are slightly over the 50A(2A):

Up to 6 panels in 2S3P you can connect to a 150/100:

For the last single panel you could use a 100/20:

So to use all of your panels you need the 100/50 you already have + 150/100 + 100/20

Using all of your panels at one MPPT is not possible with a 24V System.


100-50-na.png (51.9 KiB)
100-50-a.png (49.4 KiB)
150-100-a.png (49.7 KiB)
100-20-a.png (47.8 KiB)
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david-chops avatar image david-chops commented ·

Matthias , Thank you! I believe I am starting to get how this works

quote from your reply - "With your 100/50 you can connect 3 of those panels in parallel and you are slightly over the 50A(2A): "

So do I understand this correctly that its ok to go over on the amps because the MPPT will regulate that? (but not on volts because it will damage MPPT)

If true, how far might I be able to safely go over on amps? Would I be able to connect 5 of these panels in parallel? (using the 100/50)

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JohnC avatar image JohnC ♦ david-chops commented ·

There's a limit on Amps, but it applies to the input Amps.

Your 100/50 is rated for 60A, as Isc. Yours are 9.83 Isc, so you could parallel up to 6x of those panels.

https://www.victronenergy.com/upload/documents/Datasheet-BlueSolar-charge-controller-MPPT-100-30-&-100-50-EN.pdf


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david-chops avatar image david-chops JohnC ♦ commented ·

Thanks! I'm getting close to figuring this out. Your help is really appreciated :)

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Matthias Lange - DE avatar image Matthias Lange - DE ♦ david-chops commented ·

The 50A you have at the battery side of the MPPT.
At the PV side you can connect up to 60A Isc -> 6 of your panels.
But you can't use the energy they can produce because the output to the battery is limited to 50A.

Under good conditions (cold and sunny) you will get the 50A already with 3 panels.
I would not recommend to connect more than 4 to one MPPT 100/50.

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david-chops avatar image david-chops Matthias Lange - DE ♦ commented ·

Thank you!

OK, so if I wanted quicker recovery in low light and/or hotter temperature conditions, then adding a4th or 5th panel might make sense? With the only downside of being maxed out on 3 panels during cooler sunny conditions?

Because Amp output by the panels fluctuate depending on the light/temp conditions? Do I got it?

This is a big help and I really appreciate your time helping me understand.



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