Hi Guys

I  would appreciate it if you could clarify something for me - looking at the 8kw Sunsynk with 14 x 400W panels. I have space on one portion of roof for 4 panels and another portion for 10 panels. I was thinking of putting the 4 panels on 1 MPPT and then splitting the 10 panels between the 2 inputs of the other MPPT. Now the spec says max current input is 18A+18A. Does that mean max per MPPT or max per input? I'm new to this stuff but if it is max per MPPT, I assume my proposal would not work as the amps on the 10 panel MPPT (split 5/5) would be above 18A?

Any help would be much appreciated

 

9 minutes ago, Saul said:

Hi Guys

I  would appreciate it if you could clarify something for me - looking at the 8kw Sunsynk with 14 x 400W panels. I have space on one portion of roof for 4 panels and another portion for 10 panels. I was thinking of putting the 4 panels on 1 MPPT and then splitting the 10 panels between the 2 inputs of the other MPPT. Now the spec says max current input is 18A+18A. Does that mean max per MPPT or max per input? I'm new to this stuff but if it is max per MPPT, I assume my proposal would not work as the amps on the 10 panel MPPT (split 5/5) would be above 18A?

Any help would be much appreciated

 

What are the panel specifications?

There is a good step by step guide here https://unboundsolar.com/blog/string-sizing-guide

 

 

 

Edited March 8, 20215 yr by YellowTapemeasure

Thanks.  Key specs are VoC 49.5V; Vmp 41.17V; Isc 10.3A; Imp 9.72A

From a voltage point of view, between 4-9 panels on a string looks fine. My concern is on current - Imp x 2 will exceed 18A suggesting that the 2 strings in parallel would be problematic, but I don't know if practically speaking it really is.

 

32 minutes ago, Saul said:

Thanks.  Key specs are VoC 49.5V; Vmp 41.17V; Isc 10.3A; Imp 9.72A

From a voltage point of view, between 4-9 panels on a string looks fine. My concern is on current - Imp x 2 will exceed 18A suggesting that the 2 strings in parallel would be problematic, but I don't know if practically speaking it really is.

 

As you can see from the sizing guide, you'll need some more specs than that, like temp coefficient etc. to do a proper plan. Why don't you share the full specs?

If you look at the 8k Sunsynk's DC specs, 10 panels on one MPPT won't fly, not because the current is way over (it will clip it) but it's the high voltage that's the problem. I would be careful of anything over 400V, but that's just me.

Why are you considering such high wattage panels, do you have limited optimal space? If not, consider lower wattage panels, just more of them, it's more economical (better kWp/ Rand).

33 minutes ago, YellowTapemeasure said:

As you can see from the sizing guide, you'll need some more specs than that, like temp coefficient etc. to do a proper plan. Why don't you share the full specs?

If you look at the 8k Sunsynk's DC specs, 10 panels on one MPPT won't fly, not because the current is way over (it will clip it) but it's the high voltage that's the problem. I would be careful of anything over 400V, but that's just me.

Why are you considering such high wattage panels, do you have limited optimal space? If not, consider lower wattage panels, just more of them, it's more economical (better kWp/ Rand).

5 panels on two strings on MPPT 1 would give you just under 250v and just over 19A. This is within the range of the MPPT. 

Second mppt you can have 4 panels giving you 200v and 9.76A. 

Newer models that arrived are rated at 21A+21A

Thanks guys.

 

Yes, wattage is higher because of space issues. But I think the voltage is well within bounds.

@Achmat, I see you have 2 x 11 panels(!) on one MPPT -  not sure what panels you have but are you seeing any issues with either current or voltage?

 

 

 

12 hours ago, Saul said:

Thanks guys.

 

Yes, wattage is higher because of space issues. But I think the voltage is well within bounds.

@Achmat, I see you have 2 x 11 panels(!) on one MPPT -  not sure what panels you have but are you seeing any issues with either current or voltage?

 

 

 

I have 11 x 305w Canadian solar panels on a string and voltage peaks at 370v. I could probably push this to a max of 12 x 305w panels per string. 

Thanks. Are you seeing any clipping of current if/when it exceeds 18A? 

1 hour ago, Saul said:

Thanks. Are you seeing any clipping of current if/when it exceeds 18A? 

Not sure if it has done any clipping but I have seen it reach 18.9A.

 

Thanks.

BTW, is that the Solarman app interface you're using to show the data?

16 minutes ago, Saul said:

Thanks.

BTW, is that the Solarman app interface you're using to show the data?

Yes. Solarman Smart app.