Hi, hoping someone can explain this to me, on the SunSynk the datasheet says that it has a max DC voltage of 500V, so it is my intention to run two strings of 10x Canadian Solar 410W panels, which would give a VOC of 476V /mpp. But on the very next line in the spec sheet it states that the mpp working range is 125V-425V, can someone please explain this to me? 

In easy terms you should stay under the 425V for your setup, but if there is a spike (short burst) up to 500V the smoke should not come out of the inverter.

The MPPT is a set of electronics to try and optimise the power (Watts) you get from the panels. The panels work at a certain voltage (V) while producing current (I in Amps).
P = V * I

What the MPPT does is to try and keep the current draw such that the voltage stay at the optimum value. So if the voltage drops because the is less light it will limit the current until the voltage recovers. (this is a bit simplified)

The MPPT in your inverter was designed to work within the 125-425V range. While the electronics may not pop if you go over 425V, the MPPT cannot give you the best result. 

So it isn't actually possible to use a full 8kw array made up of 360-410W panels with SunSynk inverters? As either the voltage or amperage will always be out of range 

Correct. You will find most MPPTs will be like this. The power is always the perfect value you could get if all is matched perfectly, but it is not always that easy to find the perfect panel that match. 

With that said, you normally can over spec your panels about 10%-20% on current (the Amps) to make up for imperfect weather and losses. But not on the voltage.
Too much current on a perfect day will just be clipped or worst case reboot the MPPT (if less than 25% over), while too much voltage will make the magic smoke leave the electronics.

Thanks Louis makes sense, in this case I shouldnt have a problem if I keep the panels in series within voltage range and parralel them at the inverter (impp of 9.7A/panel), even though the max amps /mpp is 18A, SHOULD the excess amperage be clipped or WILL the the excess amperage be clipped? 

The inverter should handle that. Nothing you need to do.
 

I have a 8kw Sunsynk and has not experienced clipping yet, I have seen readings as high as 11.5A on single mppt.

I have 18 * 400w mono Jinko Cheetahs panels,  split 9 on each mppt which in theory should only produce 7200w in total but have attained 7600w max so far.

 

6 minutes ago, lancelot said:

I have a 8kw Sunsynk and has not experienced clipping yet, I have seen readings as high as 11.5A on single mppt.

I have 18 * 400w mono Jinko Cheetahs panels,  split 9 on each mppt which in theory should only produce 7200w in total but have attained 7600w max so far.

 

It will not clip the amps if you only have one string on an MPPT as each MPPT can accommodate 18A on the 8kw Sunsynk inverter.

I have 2 strings of 11 x 305w panels on one MPPT and the inverter does clip the Amps to 18A.

On the other MPPT I have one string of 6 x 305w panels and experience no clipping.

I thought so to but see image below where the total Pv amps is 22.2a

7 minutes ago, lancelot said:

I thought so to but see image below where the total Pv amps is 22.2a

Total amps would be 18(PV1) + 18(PV2) = 36A.

If you add a second string to PV1 or PV it will clip the total on that MPPT to 18A.

PV3 and PV4 does not exist on the inverter. It's only on the Solarman app for other inverters that have 4 MPPTs. 

Edited October 13, 20205 yr by Achmat

Ooh so 18A PER mppt,didnt know that thanx.

Good info on here. 

In other words, can i push the 8kW MPPT to 22.2A (ISC) without blowing it up? 

12 Panels per MPPT (6/6 415Wp CS)

VOC 47.8

VMP 39.3

ISC 11.14

IMP 10.56

7 hours ago, Johnny Wasinda said:

Good info on here. 

In other words, can i push the 8kW MPPT to 22.2A (ISC) without blowing it up? 

12 Panels per MPPT (6/6 415Wp CS)

VOC 47.8

VMP 39.3

ISC 11.14

IMP 10.56

Are those figures at STC or NOCT?

Regardless, 12 panels at a VoC of 47.8 = 573.6 volts, will blow the MPPT for sure (and that's not even taking into account low temperatures).

A good panel sizing guide here

I think Johnny Wasinda is refering to putting them in 6s2p giving him 22.28A on the 22.2A limit of the inverter.

That should be fine. The inverter will just clip the extra amsp

Am also trying to determine my best panel config for the upgrade to Sunsynk - although 2x 5kW - and would appreciate a sanity-check of my plan (all figures STC):

• MPPT 1: 8x 380W panels, VOC 48.82V (=390.56 total), ISC 9.95A
• MPPT 2: 6x 380W panels, VOC 48.82V (=292.92 total), ISC 9.95A
• MPPT 3: 8x 465W panels, VOC 51.92V (=415.36 total), ISC 11.59A (NOCT VOC 49.01V = 392.08V total, ISC 9.36A)

All strings into different directions.

That should work, or not?

@leshen You seem to be very knowledgeable around the Sunsynk. Would be able to help me with my question above please? Especially for MPPT 3

Thanks in advance 🙂

Thanks again to @leshen for taking the time to discuss my plan over the phone and give me valuable advice. Really appreciate it !! 👍

28 minutes ago, wolfandy said:

Thanks again to @leshen for taking the time to discuss my plan over the phone and give me valuable advice. Really appreciate it !! 👍

Anytime Andy

45 minutes ago, wolfandy said:

Thanks again to @leshen for taking the time to discuss my plan over the phone and give me valuable advice. Really appreciate it !! 👍

So how do your planned strings look now? Care to share (so that we all benefit)?

5 minutes ago, YellowTapemeasure said:

So how do your planned strings look now? Care to share (so that we all benefit)?

@leshen advised that the string for MPPT 3 will be no problem. The strings for MPPT 1 and 2 can be up to 9x panels (even though I think I will start 6x on each until I can source more of those panels) 

7 minutes ago, wolfandy said:

@leshen advised that the string for MPPT 3 will be no problem. The strings for MPPT 1 and 2 can be up to 9x panels (even though I think I will start 6x on each until I can source more of those panels) 

And at what location is the install? And the azimuth for the panels?

Edited May 19, 20215 yr by YellowTapemeasure

8 minutes ago, YellowTapemeasure said:

And at what location is the install?

In Somerset West

Each string facing a different direction (1 towards morning sun, 2 towards evening sun, 3 towards main direction - sorry, not at home at the moment, so struggling with headings 😉)

If I remember correctly main direction is around 330 degrees, which would make the other directions around 240 and 60

Edited May 19, 20215 yr by wolfandy
Added info

1 minute ago, wolfandy said:

In Somerset West

Each string facing a different direction (1 towards morning sun, 2 towards evening sun, 3 towards main direction - sorry, not at home at the moment, so struggling with headings 😉)

OK, so that makes it

Somerset West:

• MPPT 1 (East): 8x 380W panels, VOC 48.82V (=390.56 total), ISC 9.95A
• MPPT 2 (West): 6x 380W panels, VOC 48.82V (=292.92 total), ISC 9.95A
• MPPT 3 (North): 8x 465W panels, VOC 51.92V (=415.36 total), ISC 11.59A (NOCT VOC 49.01V = 392.08V total, ISC 9.36A)

I'm in Midrand, and I have 2 north-facing strings of 8 380W panels, I concur that I can also put 1 more panel on each string (5K Sunsynk). With you being closer to the ocean, it would be far more temperate, added the fact that your strings are E/W facing, yours is far less risk than mine. 

1 hour ago, wolfandy said:

In Somerset West

Each string facing a different direction (1 towards morning sun, 2 towards evening sun, 3 towards main direction - sorry, not at home at the moment, so struggling with headings 😉)

If I remember correctly main direction is around 330 degrees, which would make the other directions around 240 and 60

I'm also in Somerset West. God luck with the install and keen to compare similar systems with different panel orientation. 

 

My panels are probably about 8° on my carport. So very flat. 

23 hours ago, Achmat said:

I'm also in Somerset West. God luck with the install and keen to compare similar systems with different panel orientation. 

Sounds good 🙂 I'm hoping that my new system will be installed next week (or at least parts of it...). I'll post something here once I have a first bit of data