Smart Solar MPPT 150/100 VE.Can and PV panel configuration

Q&A and troubleshooting
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1

Hi everyone,

I have a SmartSolar MPPT 150/100 VE.Can charge controller. At the moment, I’ve got 8 JA-Solar JAM60D42-525/LB panels connected to it, with the following specs:

Voc = 43.73 V

Vmp = 36.37 V

Isc = 15.21 A

Imp = 14.35 A

The panels are wired in a 2S4P configuration, so 8 panels in total, giving about 4,200 Wp. As you know, the SmartSolar MPPT 150/100 has a max short-circuit current (Isc) limit of 70 A. My current setup gives Isc = 4 × 15.21 A = 60.84 A — all good so far.

My question is: can I safely add one more string, so the setup becomes 2S5P (10 panels total, 5,250 Wp)?

In theory, that would exceed the controller’s Isc spec, since 5 × 15.21 A = 76.05 A.

However, I’ve noticed that Victron allows a bit of margin on this for the MPPT RS series — as long as the panels are wired correctly, since reverse polarity damage wouldn’t be covered by warranty anyway.

I’m planning to be extra careful with the wiring. I’m using a proper solar combiner box with fuses and protection for each string, so I’m not worried about connection mistakes or short-circuit risks on the PV side — that’s well protected.

What’s puzzling me is that even with the current setup, I’ve already seen panel operating currents higher than the theoretical Isc. I’ve seen charging currents around 65 A when the sun is really strong.

Can the actual charging current of the controller exceed the Isc value from the panel spec? I understand these peaks are temporary, but if I add a fifth string, I’ll definitely go over 70 A at times.

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I also know I could add more panels by changing the wiring to 3S4P — that would give me 12 panels total and about 6,300 Wp. But I’d rather not go with 3S because my panels get some shading from trees, especially in winter when the sun is low. In that case, a 2S setup performs better than 3S.

P.S. Just to clarify regarding my battery voltage — I’m using Li-Ion NMC batteries in a 15S configuration. I charge them up to 61.50 V, which equals 4.10 V per cell.

2

I Would rearrange the old and new strings to give you 3S3P, as you cannot safely exceed the max input current with Isc. If you don’t want to go 3s, then you need an additional controller.

This will give you 9 rather than 10 panels.

What’s puzzling me is that even with the current setup, I’ve already seen panel operating currents higher than the theoretical Isc. I’ve seen charging currents around 65 A when the sun is really strong.

So? The standard conditions for the rating are at 1000W/m^2, at 25C. The sun can get up to 1300W/m^2, and if the temperature is lower than 25C (module temperature) then the current will also be higher. Yuo need to take this into account when planing your system, as exceeding the max input current rating of the MPPT can cause internal (irreparable - unless you are v.skilled with electronics) damage.

3

Hey Mike, thanks for the comment!

I’m curious though — why do you suggest going with a 3S3P setup instead of 3S4P? Right now, I’ve got four parallel strings of panels, and the short-circuit current is still within the controller’s specs. The configuration I was planning would give me 12 panels total, so about 50% more power compared to what I have installed now.

Of course, the downside is that with shading, performance drops would affect 3 panels at a time instead of 2 like in my current setup.

4

Try MPPT Calculator - Victron Energy.

70A is the PV input limit on 150/100.

5

Ok, what happens if I exceed that current?

Will the charger get damaged, or will it just not use the full power of the panels? In the documentation for the Victron MPPT RS, it says you can safely exceed the maximum short-circuit current by 50%. Does the same rule apply to the SmartSolar models?

6

Put in your panel array into the victron mppt calculator (link on previous post)and see what is recommended. You may be happy what you’ll find out.

In short, yes you can over panel and the mppt will throttle amps. Most of my arrays are over paneled to get max winter production, summer time i have too much and cant use it all.
But max voltage on mppt is a hard limit or magic smoke may appear.

7

I’ve already tried that calculator before. Unfortunately, it doesn’t suggest any configuration. With my current setup, the result is → No matching controllers found. However, when I change it to a 3S4P setup, it recommends the MPPT 150/85 and gives the following data:

  • MPPT max input voltage: 150V

  • PV voltage at 60°C (min): 90V

  • PV voltage at -10°C (max): 147V

  • MPPT rated charge current: 85A

  • MPPT charge current at 60°C (min): 85A

    → Power limiting @ high temp

  • MPPT charge current at -10°C (max): 85A

    → Power limiting @ low temp

  • PV power ratio: 129%

Of course, I know that voltage is the one limit that must never be exceeded — but that’s not an issue for me in any configuration. So far, I’ve seen a maximum of around 84V (with a 2S setup), while under full sun the panels usually run at about 68V. All the better for me!

8

You need to increase cable size up from default 6mm for anything over 2S3P!!!

I just tried 2S4P with 10mm solar cable and got recomended 150/85.

Ps above was with default location / temp coefficient.

9

OK, I double-checked all the data and even went with thicker wires — now it actually recommends the MPPT 150/85 for the 2S4P setup. What’s interesting is that for the 3S4P config it still suggests the 150/85, even though it would throttle the charging power at both low and high temps. Weird that it doesn’t recommend the 150/100 instead.

The calculator for my location estimates only around 14 kWh/day, but my actual setup has hit over 26 kWh/day at peak, and I regularly get more than 24 kWh/day — of course, that’s during summer, not now. So in practice, using the MPPT 150/100 gives much higher performance than the calculator predicts with 150/85.