Hi there, I am hoping someone can throw some light onto expanding an existing Solar Panel installation once the modules used have all but disappeared off the market.

I have an existing installation of 16 x Canadian HiKu 375w Mono Perc modules (Canadian CS3L-375MS modules with 8 x modules per string x 2 strings) attached to a Deye 8kw Inverter (larger panels were not cost effective when we did the installation 2 years ago).

I upgraded my inverter 10 months ago (from 5kw), and it is now evident that I am not generating enough capacity from my solar panels and continuously have to be supplemented from the Grid, even during the day when the sun is at its peak.

My inverter allows for up to 500v per MPPT, and I am currently on max (@ 0 deg) 349 volts, so I have the possibility to expand by 3 additional modules per string as long as the VoC voltage @ zero degree does not exceed 50v per panel (mindful that Cape Town would rarely...if ever....get to 0 degrees.

The challenge I face is that these 375w modules are no longer available.

I can get Canadian Hiku6 Mon Perc 410w modules and wanted to know if there would be any issues with me expanding each string using these Canadian CS6R-410MS? (I understand that by adding these to the existing strings these modules would experience some capacity loss because I am connecting to 375w panels).

Does anyone see any issues with this?

Any input/advise would be appreciated as I would like to understand how people expand their existing installations down the line when product modules become obsolete or are upgraded by the manufacturers so frequently.

Thanks, Marco

CS-Datasheet-HiKu6_CS6R-MS_v2.1_EN-30mm-frame-1.pdf CS-Datasheet-Hiku_CS3l-375MS.pdf

Edited November 9, 20232 yr by Marcodp
Changed the heading to be more relevant.

40 minutes ago, Marcodp said:

Hi there, I am hoping someone can throw some light onto expanding an existing Solar Panel installation once the modules used have all but disappeared off the market.

I have an existing installation of 16 x Canadian HiKu 375w Mono Perc modules (Canadian CS3L-375MS modules with 8 x modules per string x 2 strings) attached to a Deye 8kw Inverter (larger panels were not cost effective when we did the installation 2 years ago).

I upgraded my inverter 10 months ago (from 5kw), and it is now evident that I am not generating enough capacity from my solar panels and continuously have to be supplemented from the Grid, even during the day when the sun is at its peak.

My inverter allows for up to 500v per MPPT, and I am currently on max (@ 0 deg) 349 volts, so I have the possibility to expand by 3 additional modules per string as long as the VoC voltage @ zero degree does not exceed 50v per panel (mindful that Cape Town would rarely...if ever....get to 0 degrees.

The challenge I face is that these 375w modules are no longer available.

I can get Canadian Hiku6 Mon Perc 410w modules and wanted to know if there would be any issues with me expanding each string using these Canadian CS6R-410MS? (I understand that by adding these to the existing strings these modules would experience some capacity loss because I am connecting to 375w panels).

Does anyone see any issues with this?

Any input/advise would be appreciated as I would like to understand how people expand their existing installations down the line when product modules become obsolete or are upgraded by the manufacturers so frequently.

Thanks, Marco

CS-Datasheet-HiKu6_CS6R-MS_v2.1_EN-30mm-frame-1.pdf 1015.5 kB · 1 download CS-Datasheet-Hiku_CS3l-375MS.pdf 597.74 kB · 2 downloads

Due to the remote possibility of a 464Voc when adding 3 I would only add 2 per string. 

As you have seen the new 410W can provide 13.23A but would be limited to the 10.94A of the 375W panels. You will still see the improvement so not a train smash. Just perhaps spend a bit more time to see if you can't get a seller with the 375W you have. Surely it's not a must do ASAP? just to get a bit more yield. 

Just my layman's 2c. MUST be checked professionally.

I'd think twice about this. Usually you can do it if the panel specs are fairly close, but here it's basically a 13A panel in series with an 11A panel. You can expect to lose around 15% of the output of the new panels by putting them in series with the older panels. Also, as you say, you could only add around 3 per string before you're starting to push the boundaries of a prudent Voc.

Why not consider putting the first two strings in parallel on the first MPPT (22A input - to be checked if it's really 22A or not down-specced), and adding a new string of maybe 6-10 of the new panel in series on the second MPPT. On the understanding that it's okay to have an unbalanced MPPT loading, which is why I'm deferring to people who know better.

Worst case you could maybe drop down to two strings of 7 in parallel of the 375W panel on MPPT1, and put anything you like on MPPT2, it doesn't have to be the same type or a similar size if it's on a different MPPT entirely. Lots of well-priced panels if you shop around, and maybe a cheap 550W  panel x 6 or times 8 could make up for the loss in output from dropping 2x375W panels.

 

Edited November 9, 20232 yr by GreenFields

21 minutes ago, GreenFields said:

Just my layman's 2c. MUST be checked professionally.

I'd think twice about this. Usually you can do it if the panel specs are fairly close, but here it's basically a 13A panel in series with an 11A panel. You can expect to lose around 15% of the output of the new panels by putting them in series with the older panels. Also, as you say, you could only add around 3 per string before you're starting to push the boundaries of a prudent Voc.

Why not consider putting the first two strings in parallel on the first MPPT (22A input - to be checked if it's really 22A or not down-specced), and adding a new string of maybe 6-10 of the new panel in series on the second MPPT. On the understanding that it's okay to have an unbalanced MPPT loading, which is why I'm deferring to people who know better.

Worst case you could maybe drop down to two strings of 7 in parallel of the 375W panel on MPPT1, and put anything you like on MPPT2, it doesn't have to be the same type or a similar size if it's on a different MPPT entirely. Lots of well-priced panels if you shop around, and maybe a cheap 550W  panel x 6 or times 8 could make up for the loss in output from dropping 2x375W panels.

 

Great well thought out suggestion to increase PV to a much higher production. Well done @GreenFields

Some members have found the inverter throttling at about 20A while spec is 22A.

Edited November 9, 20232 yr by Scorp007

Thank you for the insights @scorp007 and @greenfields - I think this is an awesome suggestion.

Just to make sure I am understanding correctly, am I correct to say that I should re-arrange my current/future installation as follows (with a small change from 7 panels to 6 panels to align the watts per MPPT).

MPPT1 - Install 2 x strings of 6 x 375w panels on MPPT1, totaling 12 panels (on MPPT1), as follows:

install 2 x strings of 6 panels in series which I would bring together (paralleled) before going into the inverter? If I am correct this would mean that each string of 6 x 375w panels would give me 2250watts per string x 2 strings totaling 4500w on MPPT1. Looking at the specs that this would give me  (to make sure I do not exceed my inverter spec), my Open Circuit Voltage (VoC), @ 25 degrees, would be 41v x 6 panels totalling 246v and because I am paralleling the 2 strings, my Voltage would not change but my Short Circuit Current (Isc) would double (because I am paralleling 2 x strings) so that would be 11.61A x 2 strings totaling 23.22A.

So, in summary, 12 panels (4500w) with a VoC of 246v and a Isc of 23.22A - all well within Inverter spec which I checked as follows: the Deye 8k Inverter [SUN-8K-SG01LP1-EU] has a MPPT input range of 150vdc-425Vdc and a PV Input current of 26Adc) .......... just as well I checked as I thought it was 500Vdc per MPPT 😞

 

Then for MPP2, I could purchase/install 8 x 550w panels in series - this would give me 4400W on MPPT2 (the VoC and Isc would be fine/in range considering the above inverter spec)

Both MPPT's would be balanced (4500W vs. 4400w), although the Amps would be different (not sure if this is an issue?)

Considering I started with 16 x 375w panels, I would then have 4 x 375 w panels over which I could use to either expand the installation in the future or use elsewhere.

Did I get this right?

21 minutes ago, Marcodp said:

Thank you for the insights @scorp007 and @greenfields - I think this is an awesome suggestion.

Just to make sure I am understanding correctly, am I correct to say that I should re-arrange my current/future installation as follows (with a small change from 7 panels to 6 panels to align the watts per MPPT).

MPPT1 - Install 2 x strings of 6 x 375w panels on MPPT1, totaling 12 panels (on MPPT1), as follows:

install 2 x strings of 6 panels in series which I would bring together (paralleled) before going into the inverter? If I am correct this would mean that each string of 6 x 375w panels would give me 2250watts per string x 2 strings totaling 4500w on MPPT1. Looking at the specs that this would give me  (to make sure I do not exceed my inverter spec), my Open Circuit Voltage (VoC), @ 25 degrees, would be 41v x 6 panels totalling 246v and because I am paralleling the 2 strings, my Voltage would not change but my Short Circuit Current (Isc) would double (because I am paralleling 2 x strings) so that would be 11.61A x 2 strings totaling 23.22A.

So, in summary, 12 panels (4500w) with a VoC of 246v and a Isc of 23.22A - all well within Inverter spec which I checked as follows: the Deye 8k Inverter [SUN-8K-SG01LP1-EU] has a MPPT input range of 150vdc-425Vdc and a PV Input current of 26Adc) .......... just as well I checked as I thought it was 500Vdc per MPPT 😞

 

Then for MPP2, I could purchase/install 8 x 550w panels in series - this would give me 4400W on MPPT2 (the VoC and Isc would be fine/in range considering the above inverter spec)

Both MPPT's would be balanced (4500W vs. 4400w), although the Amps would be different (not sure if this is an issue?)

Considering I started with 16 x 375w panels, I would then have 4 x 375 w panels over which I could use to either expand the installation in the future or use elsewhere.

Did I get this right?

You gave all correct. You don't need to have both MPPTs the same but I will not run say one at 4000W and the other at 6500W.

Instead of having 4 spare panels go 2x7/8x375W for MPPT1 and add the new 8x550W in series on MPPT. I think the Voc will be fine but have not checked their Voc or other specs. 

I make it that you can use 8 in series even for the 375W panels and used as 2 strings in parallel. Let's hear what @GreenFields@GreenFields or other members think .

This gets you nicely to the maximum for the inverter.???? 

47 minutes ago, Marcodp said:

Just to make sure I am understanding correctly, am I correct to say that I should re-arrange my current/future installation as follows (with a small change from 7 panels to 6 panels to align the watts per MPPT).

I'm not saying the Watts per MPPT must be the same. I've got one of my MPPT's in use, and the other has no panels at all, and that's perfectly fine.

What I'm saying is that the inverter has a max input of 10,400W and I don't know if it means you have a maximum of 5200W per MPPT, or if you can go safely over on the one or the other or both. Someone else must confirm that for you.

But I'd try to use different panels per MPPT all the same.

@Greenfields and @Scorp007, thank you for your insights - I have learnt so much from this discussion and now have a way forward, which I had not considered previously.

I really appreciate your input and hopefully other can also learn from this discussion in the future.

The above string configurations suggested could all work Voc in limit. The only aspect to take into consideration is that the Mpp of the charge controller is most efficient at 370v. 

11 minutes ago, GreenFields said:

What I'm saying is that the inverter has a max input of 10,400W and I don't know if it means you have a maximum of 5200W per MPPT, or if you can go safely over on the one or the other or both. Someone else must confirm that for you.

It is possible to overpanel on the 10400w for rainy days and winter months as in summer it will clip excess current but within limits and being very carefull with the maximum allowed input dc voltage of each mppt. Mppt 1 and Mppt 2 does not need to be balanced but good array design would always endeavor to balance as close as possible. For Sunsynk, Deye ,Fronius,Victron it is possible to overclock the inverter rating by 1.5 but i would not suggest this for lower quality MPPTs like Voltronic. So for Deye 8kw it could be 8000 x 1.5 = 12000w then 6kw/ Mppt.

I would like to overstate this to say that voltage is a hard limit and it is wise to calculate effect of cold weather on raising voltage so leave some margin of error on voltage. Current can exceed the stated limit because the controller will only pull the current it can use, Regardless of load the voltage will be what the cells put out subject to how the MPPT controller adjusts voltage and amps. The load has very little control over the voltage, which is why the voltage limit needs to be respected and not exceeded.

Thanks @TaliaB, @Greenfields and @Scorp007.

I have come up with the following configuration which I think is best suited for my install, while being mindful of the space I have available (panels need to be smaller than 2.1m tall) as well as my inverter specifications as follows:

Inverter Spec for Deye 8k Inverter [SUN-8K-SG01LP1-EU]

• Max PV Input power = 10400w
• MPPT input range of 150vdc-425Vdc
• PV Input current of 26Adc

The below configuration (see picture) would give me:

• 9390 watts Max PV power
• MPPT1 = Max 5250w using 2 strings, with a VoC of 305.66v and a Isc of 23.22A
• MPPT2 = Max 4140w using 1 string, with a VoC of 396.8 and an Isc of 14A

From what I can see, I cannot add a 10th panel to MPPT2 as this would increase my 'VoC' above the target range of 425Vdc and I cannot split MPPT2 into 2 strings and parallel them as this would place my 'Isc' above the 26Adc. I also cannot go to a larger panel (e.g. 545W panel) as my roof simply is not big enough to take 2 x 2.18m panels.

Do you see any issues with this config?

CS-Datasheet-Hiku_CS3l-375MS.pdf CS-Datasheet-HiKu6_460MS.pdf IMG_2263.HEIC

41 minutes ago, Marcodp said:

Thanks @TaliaB, @Greenfields and @Scorp007.

I have come up with the following configuration which I think is best suited for my install, while being mindful of the space I have available (panels need to be smaller than 2.1m tall) as well as my inverter specifications as follows:

Inverter Spec for Deye 8k Inverter [SUN-8K-SG01LP1-EU]

• Max PV Input power = 10400w
• MPPT input range of 150vdc-425Vdc
• PV Input current of 26Adc

The below configuration (see picture) would give me:

• 9390 watts Max PV power
• MPPT1 = Max 5250w using 2 strings, with a VoC of 305.66v and a Isc of 23.22A
• MPPT2 = Max 4140w using 1 string, with a VoC of 396.8 and an Isc of 14A

From what I can see, I cannot add a 10th panel to MPPT2 as this would increase my 'VoC' above the target range of 425Vdc and I cannot split MPPT2 into 2 strings and parallel them as this would place my 'Isc' above the 26Adc. I also cannot go to a larger panel (e.g. 545W panel) as my roof simply is not big enough to take 2 x 2.18m panels.

Do you see any issues with this config?

CS-Datasheet-Hiku_CS3l-375MS.pdf 597.74 kB · 3 downloads CS-Datasheet-HiKu6_460MS.pdf 681.77 kB · 1 download IMG_2263.HEIC 887.01 kB · 1 download

All looks OK. I am sure your 14A Isc you meant Imp of 26A as the Isc for the MPPT is 44A as per the specs you placed earlier. 

1 hour ago, Marcodp said:

From what I can see, I cannot add a 10th panel to MPPT2 as this would increase my 'VoC' above the target range of 425Vdc and I cannot split MPPT2 into 2 strings and parallel them as this would place my 'Isc' above the 26Adc.

10 Panels should be okay. The Voc limit is 500V, while the 425V is the upper limit of the Vmp range. Most of the time your panel set would be operating at around 10x38.4Vmp. And you've already taken into account with temperature dips down to 0 degrees, that you'd be outputting 440V max.

It also is an option to put MPPT2 in parallel also, since, as @Scorp007 pointed out, Isc, the maximum short-circuit current, is up to 44A and the 26A refers to the Imp that the 13.24A panels in parallel would clip down to.

Not critical, you have options, and it all seems to work, and be within range.

32 minutes ago, Marcodp said:

The below configuration (see picture) would give me:

• 9390 watts Max PV power
• MPPT1 = Max 5250w using 2 strings, with a VoC of 305.66v and a Isc of 23.22A
• MPPT2 = Max 4140w using 1 string, with a VoC of 396.8 and an Isc of 14A

All looks good. 

Thanks everyone for your valued insights - the learnings have been awesome - thank you.

I have formulated an updated config, using all my existing panels (16 x 375w panels) and 8 x "new" 550w panels, which I believe maximises my solar panel production, mindful of my inverter specs (Inverter Specs for Deye 8k Inverter [SUN-8K-SG01LP1-EU]: Max PV Input power = 10400w, PV Input voltage = 125vdc - 500Vdc, MPPT input range of 150vdc-425Vdc, PV Input Current of 26Adc+ 26Vdc and a Max PV Isc = 44Adc + 44Adc)

This updated config (see pic below) would give me:

• 10400 watts Max PV power (at max power)
• MPPT1 = Max 6000w using 2 x strings of 8 x 375w panels in each string, with a VoC of 346.76v @ 3 degrees ambient temp and an Isc of 23.22A
• MPPT2 = Max 4400w using 1 string of 8 x 550w panels, with a VoC of 419.50v @ 3 degrees ambient temp and an Isc of 14A

As long as there is no issue with the MPPT's being different (from a watt's perspective), this hopefully would maximise my production?

Note: Cape Town has never dropped below 3 degrees ambient temperature)

If this looks ok, I do have a question regarding MPPT1 and the joining (paralleling) of the 2 strings (each using 8 x 375w panels) - is it best to combine these strings using a MC4 "Y splitter" (see pic) on the roof and then having one 6mm cable going to my inverter (through a combiner box)?

or

Is it best to run a separate cable for each of the 2 strings, through their own separate combiner boxes each with fuses, isolator switch and SPD, and then into the inverter using the 2nd PV port available on the inverter (see Inverter picture below - PV1 has 2 ports for + and - and PV2 also has 2 ports for + and -)? 

Does this updated config look ok and if so, what would be the "best" way to parallel the 2 x strings on MPPT1?

Any insights would be appreciated...

CS-Datasheet-Hiku_CS3l-375MS.pdf CS-Datasheet-HiKu6_CS6W-MS_v2.2_F30_F35A_EN_530-555W.pdf

2 hours ago, Marcodp said:

Thanks everyone for your valued insights - the learnings have been awesome - thank you.

I have formulated an updated config, using all my existing panels (16 x 375w panels) and 8 x "new" 550w panels, which I believe maximises my solar panel production, mindful of my inverter specs (Inverter Specs for Deye 8k Inverter [SUN-8K-SG01LP1-EU]: Max PV Input power = 10400w, PV Input voltage = 125vdc - 500Vdc, MPPT input range of 150vdc-425Vdc, PV Input Current of 26Adc+ 26Vdc and a Max PV Isc = 44Adc + 44Adc)

This updated config (see pic below) would give me:

• 10400 watts Max PV power (at max power)
• MPPT1 = Max 6000w using 2 x strings of 8 x 375w panels in each string, with a VoC of 346.76v @ 3 degrees ambient temp and an Isc of 23.22A
• MPPT2 = Max 4400w using 1 string of 8 x 550w panels, with a VoC of 419.50v @ 3 degrees ambient temp and an Isc of 14A

As long as there is no issue with the MPPT's being different (from a watt's perspective), this hopefully would maximise my production?

Note: Cape Town has never dropped below 3 degrees ambient temperature)

If this looks ok, I do have a question regarding MPPT1 and the joining (paralleling) of the 2 strings (each using 8 x 375w panels) - is it best to combine these strings using a MC4 "Y splitter" (see pic) on the roof and then having one 6mm cable going to my inverter (through a combiner box)?

or

Is it best to run a separate cable for each of the 2 strings, through their own separate combiner boxes each with fuses, isolator switch and SPD, and then into the inverter using the 2nd PV port available on the inverter (see Inverter picture below - PV1 has 2 ports for + and - and PV2 also has 2 ports for + and -)? 

Does this updated config look ok and if so, what would be the "best" way to parallel the 2 x strings on MPPT1?

Any insights would be appreciated...

CS-Datasheet-Hiku_CS3l-375MS.pdf 597.74 kB · 0 downloads CS-Datasheet-HiKu6_CS6W-MS_v2.2_F30_F35A_EN_530-555W.pdf 910.41 kB · 0 downloads

Good to see all is turning out fine. 

Our installers will be in a better position to answer around the y-connectors. I am a bang Jan when it comes to these DC voltages as well as the high current on a single MC4. I prefer each string to the combiner box with all the extras. As you have 2 inputs per MPPT I would use it on the inverter and pull each string with 4mm cable to the inverter. 

This will also allow you to do fault finding easier but having access to each string if 1 panel would say have a defective bypass diode or any other fault that can affect the operation of the string. Easy then to disconnect a faulty string and still have the remaining string producing power. 

12 hours ago, Marcodp said:

what would be the "best" way to parallel the 2 x strings on MPPT1?

I know that many installers use mc4 y-connectors for paralleled strings especially for long cable runs to save on cost for copper and they are good for up to 30 amps(1000v) but for one reason i do not use them,safery for me is key so i stick to the least amount of connections on the roof. I normally run the strings to the dc combiner box next to the inverter and parallel them at the  dc mcb's. Below example of pv combiner of an installation i did. This box i still used Onesto spd's but as of late i only use Noark dc mcb's and spd's.

 

 

Edited November 12, 20232 yr by TaliaB

Thank you @Scorp007 and @Taliab - considering I want the best (safest) possible solution, this makes perfect sense.

From what I understand - both the scenarios would work:

Option 1: I could have a 3rd combiner box (so each string has its own fuses, isolator and SPD) and then parallel the 2 strings for MPPT1 at the inverter (this would be an excellent solution but will not be the most cost-effective way)

or

Option 2: I could save on the 3rd combiner box by paralleling the 2 strings MCB for MPPT1 (in the combiner box) - the MCB's, fuses and SPD already exist so there would be no need to purchase additional hardware (fuses, isolators and SPD). From what I understand, I can still then have a single 6mm wire going from my combiner box to the Inverter as the Amp rating would suffice (I've read that the Amp rating, dependent on distance, is > 30A at 15m) - so a perfect solution.

Thanks for your valuable insights - I have got some awesome learnings from this discussion and hopefully others will too.

I do have 1 last question which I touched in this discussion although not really related to it:

Can anyone explain the difference between the following Inverter specs (Deye 8K Inverter as an example):

• PV Input voltage (125vdc - 500Vdc) and MPPT input range of (150vdc-425Vdc)

and

• PV Input Current (26Adc+ 26Vdc) and a Max PV Isc (44Adc + 44Adc)

Both either refer to voltage or Amps - which do you consider when?

7 minutes ago, Marcodp said:

I do have 1 last question which I touched in this discussion although not really related to it:

Can anyone explain the difference between the following Inverter specs (Deye 8K Inverter as an example):

• PV Input voltage (125vdc - 500Vdc) and MPPT input range of (150vdc-425Vdc)

and

• PV Input Current (26Adc+ 26Vdc) and a Max PV Isc (44Adc + 44Adc)

Both either refer to voltage or Amps - which do you consider when?

NB: Voltage is to be considered 1st especially when designing your system as voltage is the part that will "blow up things" if exceeded.

Thank you, although perhaps I need to clarify my question - when would one consider the PV Input Voltage and when would you consider the MPPT Input range as both refer to voltage but have different ranges? So, the question is what is the difference and when would you use/consider each metric?

The same question would apply to PV Input Current and a Max PV Isc ?

Any insights into the difference and when you would consider each metric would be awesome?

3 hours ago, Marcodp said:

Thank you, although perhaps I need to clarify my question - when would one consider the PV Input Voltage and when would you consider the MPPT Input range as both refer to voltage but have different ranges? So, the question is what is the difference and when would you use/consider each metric?

The same question would apply to PV Input Current and a Max PV Isc ?

Any insights into the difference and when you would consider each metric would be awesome?

The input range is once you exceeded the 150V start up voltage the MPPT will still work down to 125V. This is the normal operating band for the MPPT. It seems if you exceed 425V there might be a drop in efficiency but although it is a drop I don't know is the drop 3% or may be 10%.

My MPPTs work at the same efficiency at 60V or at 250V. Cannot say if it had to go over 500V if there will be a drop. Never seen what the drop is for a Sunsynk if you are at 200V vs when at say 400V.

4 hours ago, Marcodp said:

I do have 1 last question which I touched in this discussion although not really related to it:

Can anyone explain the difference between the following Inverter specs (Deye 8K Inverter as an example):

• PV Input voltage (125vdc - 500Vdc) and MPPT input range of (150vdc-425Vdc)

and

• PV Input Current (26Adc+ 26Vdc) and a Max PV Isc (44Adc + 44Adc)

Both either refer to voltage or Amps - which do you consider when?

PV input voltage - 125Vdc-500Vdc - your ultimate limits of operation. Below 125Vdc the inverter will shutdown, or basicaly not produce anything, like at night, or if you've put just 2 panels in series. May as well have nothing. Above 500Vdc you can expect permanent damage to the inverter. This is especially relevant for the Voc - open-circuit Voltage when there's no current flowing in the circuit yet, just before power generation starts. Adjusting for temperature fluctuations, keep the Voc safely away from 500V

MPPT input range 150Vdc-425Vdc - your normal operating parameters. Although around 370V is the optimum Voltage, the normal working range is a bit wider. You need 150V to start up the generation, and once the generation is up and running, the Voltage may drop as low as 125V without shutting down. Above 425V the inverter will start to cut back on generation to protect itself. Any operation away from the recommended range is not efficient.

PV input current 26A+26A - this is the first parameter to consider for normal operation. Imp - the Current at maximum power generation point - should ideally be below this value. In your case it's around (11A+11A) 22A on MPPT1, and 13.3A on MPPT2, so easily within spec.

If the current value exceeds 26A by a small margin that is not a train smash. Say if you wanted your 13.3A panels in two strings at 26.6A on MPPT2. All that would happen is that the inverter would limit the current to 26A, and thereby limit the current to a value below that which your panels produce peak power. Not critical for these small excesses, but you don't want for example 22A of panels on a 13A MPPT of the 5kw sunsynk, that is just a total waste of power.

The Isc - Short-circuit current - is a fault condition. Just be sure that the inverter will not be damaged if your panels have a short circuit, ie. the Isc of the panels in total should not exceed the 44Adc value that the inverter can handle. You seem to be safe on this aspect.

 

This makes sense - thank you @greenfields & @scorp007.

This was an excellent discussion, where general information is limited, and I for one have definitely benefitted from the insights provided.

Hopefully others will also learn/benefit ...

 

Just now, Marcodp said:

This makes sense - thank you @greenfields & @scorp007.

This was an excellent discussion, where general information is limited, and I for one have definitely benefitted from the insights provided.

Hopefully others will also learn/benefit ...

 

I would like to add something to this great topic. 

We sometimes see guys getting a current higher than the Imp. This morning at 10h during cloud edge I got the highest output from this string. The short term output was 11.1A while the spec Isc is 11.2A. Although very high this came at the expense of the voltage dropping down to 31V while the Vmp volts per spec is 39V. This brings me to the fact one must have the voltage and amps in order to know what the maximum Watts was.