Should we stress the max Amperage when choosing panels

Charge Controllers (MPPT, PWM)
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This might seem like an obvious question with a clear answer for some.

With the increased availability of higher wattage panels

Looking into adding panels, I’ve come to realize that Team Blue has an advantage as they can choose what they need. However, those of us who are looking for an all-in-one solution like the Sunsynk Deye LUX face a different situation.
I chose these products because I have friends who already have them installed, and they are widely advertised and installed.
When it comes to matching your panels with your inverter, I’ve noticed numerous advertisements showcasing their installations, all of which seem to be functioning well. However, I wonder what might be missing or if I’m overlooking something important.

For the purpose of this discussion, let’s focus solely on the current rather than the MPPT string voltage. As this is easier to see

The Lux SNA5000 has a maximum current of 12.5 A, whereas the Sunsynk/Deye 5Kw has a maximum current of 13 A. To avoid an exhaustive list, I’ve seen various panels being installed with current ratings like 13.5 A, 13.11 A, and 13.8 A.

My concern is: where should we draw the line? Have some people learned from experience, or could we potentially be dealing with ticking time bombs?

A few points to consider: I’m well aware that panels might not always operate at their maximum capacity. Additionally, there’s the ISC (short-circuit current) to take into account.

Mod note: Edited some obvious typos

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Recently I bought a 2nd hand Solis.

Now, I know that with Victron MPPTs you can basically nearly do as you want, stick to the max volts basically, and oversize them as you want. Like 250/85, I can take it to 122% oversized, with 6kw of panels (600w x 10). Volts are within safety margins for 0 Deg temp.

And Victron gave that calculation. So I’m happy.

Solis … big was my surprise with the hold on, careful now, max 11amps from the array. :rofl:

Yeah, that threw a spanner in the works, when one likes Canadian panels but has to get preferable 350-365w. Want to max it, 3kw. The 11a is gooing a lekker spanner at me.

My point, yes, there are T&Cs on all MPPTs … and that until you posted, I never realized just how versatile the Victron MPPTs are.

Ps. NEVER exceed an MPPT’s max volts, a rule of thumb for all of them.
The amps, a good MPPT will clamp the excess … but note, I only know Victron MPPTs. Cannot speak for any other, not even Solis. :rofl: - yet.

My 2 cents.

FWIW, the issues come in on cold sunny days. Like my 5.2kw array, can easily reach 6.4kw on lekker cold sunny days, with cloud effect.

My point: It takes one brilliant awesome cold sunny day, to pop an MPPT that was not specced properly … and the weather patterns are changing …

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Maybe slightly of topic. Is it possible to get a report on your MPPT’s that shows the max volts they reached since first put into operation?

I’m considering rewiring my strings from 2S3P to 3S2P but would want some comfort. Will also mean less cabling.

4

For Victron it’s in the console history.

image

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That is EXACTLY what I’m contemplating … from 4S3P to 5S3P … I have 3 more spares.

Seems my volt max sits at 188.87v. (Thanks, @mmaritz, for that reminder!)
So max on the MPPT shows 188.87v / 4 = 47.2175v per panel.
So, 5 x 47.2175v = 236.0875v - far removed from the 250v max.

My 150 is hitting 142.27v - I think will leave it as is. :slight_smile:

Panels specs - these Canadians ARE impressive:
Canadian Kumax CS3U 350P
Pmax: 350W
VMPP: 39.2V
IMPP: 8.94A
Voc: 46.6V
Isc: 9.51A

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The ratings you are referring to is the MPPT max control point. There should also be an actual max PV panel rating in the case of something like the Sunsynk, and they have in fact started to publish them (IIRC the 8kW has it in the latest datasheet). You should not exceed that value, which is usually in the order 125% of the MPPT rating.

In the case of Victron buck MPPTs (not the high-voltage stuff), the limit is a lot higher just because of the topology that it’s not even worth publishing.

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I’ve got 2 sunsynk 5kw inverters with the following panels

Inverter 1
East 8x420 Canadian poly. 3360w
West top 8x390 JA 3120w

Inverter 2
North 9x460w jinko 4140w
West down 8x360w Canadian 2880w

Having them in different directions help and the north array is made up of 2 sections of 4 panels and 5 panels. They are all on optimizers and get shade at different parts of the day but currently the north array give me more than 33% of my total daily production.

When I got my first inverter with the 420w panels, the current was rated at 11A but it would clip at 9.9A and around midday, I would see the current flatline at 9.9A.

Then they increased this to 13A. So the Sunsynk’s to clip as well.

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I cannot find this sub menu. Under what menu is this? Sorry, internet is really slow today and it takes ages to select something on VRM.

Edit: I found it thank you very much.

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So I have on MPPT (1) a max of 119.23V ever reached, and on MPPT (2) a max of 111,6V.

This is on 415W panels with a VOC of 37.32V and at max power 31,45V

So I guess I would be ok to do 3 panels in series. If going by MPPT (1), that would put me at VOC 111,96 which is miles away from 150. And this is over a 2 year period more or less.