Hi ladies and jellybeans greetings …would appreciate some input plz
My scenario as follows :
I.have a sunsynk 5kw with hubble am2 backup system working like a donkey and very satisfied now i bought 6 canadian 550 watt panels i want 2 install …my friend installed his luxpower 2 day with the same amount of canadians the result was that the installer told him.that he could only.put 5 on 1 string as the amps were more than 13 amps and it was 2 strong for 1 mppt…my question is will i encounter the same issue on my sunsynk and if advise on panels per panels per string plz …note i only have east and west facing roofs thx guys
uuuuh… the number of series panels per string is not going to bring the amps down. That changes the voltage.
If the spec sheet I googled is correct, this inverter wants a voltage between 150V and 425V, max 11A per tracker, with the sweet spot around 380V. That means that voltage-wise 6 panels is just fine (puts you around 300V on a cold morning, 240V most other days), but since the Imp on the 550W modules is 13.2A, you’re still screwed even if you go with less panels.
There is some evidence to suggest that a firmware update allows the sunsynk to do 13A per tracker. You’re still on the limit, and I have no idea what happens if you exceed it. Some sources suggest that the MPPT may not be able to stably track the power point. Also, the 13.2A is an STC value (standard test conditions), which is typically more than we really get in South Africa. In other words, you may be able to (just barely) get away with it. But you may as well put up all 6 panels if you’re going to do that.
I remember this same scenario playing out with Goodwe inverters in the past, when the panels also started to exceed the capability of the inverter’s MPPT.
As @plonkster said, whether you have 5 or 6 or 10 panels in series, the current will be the same.
The minimum number of panels that you should have per mppt is 4 assuming the Vmp is in the mid 40s. I have seen people run too low voltage and then they have endless issues with the mppt not being able to generate power consistently.
Regarding the current, when the 5kw Sunsynk’s were first released, they could handle 10A and the current would be limited to 9.9A. I hit this pretty often as my panels were rated 10.4A. What this meant was that I was losing some power from the panels (0.5A x Vmp) the inverter can now accept 13A anything above would be limited.
The voltage in this case is far more important. If you exceed the voltage of the mppt, you release the magic smoke.
TLDR: try to get panels that match the Imp of the inverters 13A and the Combined Vmp of the array string should be within the mppt operating range.
In that case I would say the 13.2A panels is going to be fine.
I don’t remember the exact details, but basically a short circuit should not cause so much current to flow that the switching gear (MOSFETs most likely) cannot handle it. The MPPT will generally limit the current to below this value, but during a fault condition, it could exceed it. There is often a little room above the max value, and as noted, this is at STC.
So you should probably be okay with those panels.
Those panels are fine with the Sunsynk.
The absolute limit is a bit more intricate to determine than alluded to above, and generally indicated for the inverter - but in the case of the Sunsynk, it is not. Basically, either your switching devices (FETs) have to have a lot of margin, or you have to respond faster than the worst case slope (mostly determined by the inductance). I suspect in the case of the Sunsynk they have ample margin on both, which is why they don’t indicate max panel Isc (the 12kW 3ph is the only one I know that does have a limit indicated in the datasheet).
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True. Another example would be the MPPT RS. Max PV current is 18A, but the Isc is 20A, so you have almost 10% room at the top.
What made this question hard to answer, is that it wasn’t clear to me which value this is. What I’ve read elsewhere seems to suggest it will limit the max at 13A, but without that second Isc number, it was difficult to say how much room there is.
At least the main question was answered: The neighbour who was told to limit to 5… was told wrong 
Thx to all for the input i appreciate
Why is nobody talking about Isc?
A few things to consider:
- NEVER EVER go over the V(oc) rating of the MPPT, that’s instant sparks
- Never go over the I(sc) of the MPPT, that is instant work smoke coming out.
So in this case you have a Isc rating of 14Amp, (I think, too lazy now to double check). So using the IEC standards your preferred Isc rating on the MPPT should be Panel Iscx1.25 = 17.2A
So you need to ensure that your 5kW can handle 17.2A at least.
Now, this is where it gets ugly, for some reason Sunsynk decided it is not pertinent to provide the Isc value of the MPPT and the max current as on the datasheet (older versions) or the nameplate is the Imp(Max)…
The bad news here is that the new datasheet gives you a 17A MPPT-Isc, so will you risk your inverter?
You can ignore IEC best practice and not use the 1.25x… You can, up to you.
As for the Imp, what will happen if you have 11A MPPT so you will lose out on 2A, 40V = 80W give or take?
This does have benefits in the winter when most others will not be able to get the maximum out of the modules you will.
Risk vs Reward…
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