@EugeneS Do you have the option of doing an East West split? 

Would definitely recommend it if you can, flattens the peak out and you get solar power earlier in the morning and until later in the afternoon. 

Thanks all, the 9 panels were installed yesterday. All seems good so far. Was overcast when we connected them and reading was at 410v. I have peace of mind with the 9 panels and think I'm still generating more than what I need. 

Hi, read through this post because My 8kw sunsynk will arrive in a few days. Trying to work out the maximum amount of panels I can use and this post was very helpful, 

just a quick question,

the max dc input voltage is 500v and on the 8kw sunsynk spec sheet it states the mppt range 125v- 425v, now is this figure per mppt or for both mppts together.

you mentioned that 9x 540watt panels will be okay on one string on one mppt, but can you add another 9 x 540watt panels on the 2nd mppt. 9 panels east facing and 9 west facing. 
 

if this is possible then won’t it exceed the maximum dc input voltage of 500v if all your panels are almost producing max wattage at mid day? 

Each MPPT can accept up to 500V from the Voc of the panel. You don't add the inputs but they are in parallel in the inverter.

You will never get the highest voltage at mid day. It will be when nearly zero current=power is flowing on very cold mornings.

4 minutes ago, Scorp007 said:

Each MPPT can accept up to 500V from the Voc of the panel. You don't add the inputs but they are in parallel in the inverter.

You will never get the highest voltage at mid day. It will be when nearly zero current=power is flowing on very cold mornings.

@Scorp007Thanks so much

so just making sure it is possible to install 9x 540watt on one string per mppt at a Voc of 49.6v. Making a total of 18 panels without causing potential damage to the inverter 

2 minutes ago, Derek Ramos said:

@Scorp007Thanks so much

so just making sure it is possible to install 9x 540watt on one string per mppt at a Voc of 49.6v. Making a total of 18 panels without causing potential damage to the inverter 

496V just makes it but for me it is too close for comfort when using 10 but 9 is fine.

7 minutes ago, Scorp007 said:

496V just makes it but for me it is too close for comfort when using 10 but 9 is fine.

Thank you

Should the number of panels connected to each of the 2 mppt’s be matched or are they working independantly?  My roof layout allows for 9 panels in a string on mppt 1 and 5 panels in a string on mpp2. 

12 hours ago, D4Solar said:

Should the number of panels connected to each of the 2 mppt’s be matched or are they working independantly?  My roof layout allows for 9 panels in a string on mppt 1 and 5 panels in a string on mpp2. 

They don’t need to match, 9 on mppt 1 and 5 on mppt 2 is fine. It obviously wont be the same amount of wattage but once they come into the inverter the wattage is combined 

Hi @Derek Ramos

I have a dilemma related to the post on not needing to match panels on an mppt.

i have 12 by 650W panels connected in series to an 8Kw Deye inverter. I have read that sometimes the voltage of the panels can fluctuate in winter, so i am concerned that I may exceed the max v input of 500V. If i connect them in parallel and split them into 6 each I'm worried that my solar generation

will be reduced.

 

Both my strings face north and from 11am to 4pm i get full sun on all the panels. Should i split them into 8 on one mppt array and 4 on another, would that be more efficient than a 6, 6 split or does the inverter just total whats being generated regardless of the split? I live in Gauteng, South Africa.

 

i hope my questions makes sense. I am a newb.

 

 

 

 

 

 

 

10 hours ago, Joe Sun said:

Hi @Derek Ramos

I have a dilemma related to the post on not needing to match panels on an mppt.

i have 12 by 650W panels connected in series to an 8Kw Deye inverter. I have read that sometimes the voltage of the panels can fluctuate in winter, so i am concerned that I may exceed the max v input of 500V. If i connect them in parallel and split them into 6 each I'm worried that my solar generation

will be reduced.

 

Both my strings face north and from 11am to 4pm i get full sun on all the panels. Should i split them into 8 on one mppt array and 4 on another, would that be more efficient than a 6, 6 split or does the inverter just total whats being generated regardless of the split? I live in Gauteng, South Africa.

 

i hope my questions makes sense. I am a newb.

 

 

 

 

 

 

 

Hi Joe, 

you are 100% correct, you have to many panels on one string… after getting some professional advice I landed up using 16x 470 watt panels… 8 panels per string just for safety purposes… in future if I don’t find the same panels I can connect all 16 panels on one string by connecting 8 in parallel… but that’s another story.
 

about your setup, if you connected  6 panels on each string it won’t effect your solar production because your panels will still be hitting the same amount of sun time… your inverter will combine both string solar production… even if it did effect your production I would still only put a maximum of 8 for the safety of your inverter. Someone told me that they just make the 150v startup voltage with 4 panels on one mppt so I would suggest going 6 panels per string per mppt. I think you just looking for trouble have 12 panels on 1 mppt. 

The choice should be simple. Does one run the risk of damaging the inverter with all in series or think you might loose a few watt with no damage.  Just the waiting time to have the inverter repaired with no PV system should be enough reason to use 2Px6S.

11 hours ago, Joe Sun said:

I'm worried that my solar generation will be reduced.

It'll be a lot more reduced if the MPPT gets fried...

But the number of panels in series depends on the Voc mostly, and 650Wp panels available today generally have much lower Voc than 550Wp or 450Wp panels.

5 hours ago, P1000 said:

It'll be a lot more reduced if the MPPT gets fried...

But the number of panels in series depends on the Voc mostly, and 650Wp panels available today generally have much lower Voc than 550Wp or 450Wp panels.

And then the current goes to over 17A per string. Using 2 strings in parallel you might end up with the MPPT throttling if there is only 1 MPPT input.

Once again we can't just look at the Voc. Sunsynk with 2 MPPT seems fine.

Hi, thanks guys for all your responses. It was very helpful.

I am going to split into two, as a test I'll go 5  for mppt 1, 7 for mppt 2, slightly higher on one mppt,  still safe for the inverter and overcomes the startup voltage limitation. 🙂

 

 

 

 

 

 

 

 

 

 

 

 

The 8 kW is rated at 22 amps per string, what is the current rating for the panels, remember current adds up when paralleling strings, you will have a good bit of clipping

Just to confirm you can run the PV on a Sunsynk 8kw with only 1 mppt connect? 

What would be the best approach if you wanted to do a East, North, West split? 

11 hours ago, Chris_S said:

Just to confirm you can run the PV on a Sunsynk 8kw with only 1 mppt connect? 

What would be the best approach if you wanted to do a East, North, West split? 

 

11 hours ago, Chris_S said:

Just to confirm you can run the PV on a Sunsynk 8kw with only 1 mppt connect? 

What would be the best approach if you wanted to do a East, North, West split? 

Yes you can use only 1 MPPT but not for the 3 strings you mention. East and West in parallel into MPPT1 as long as the combined current is not over 22A. Then the North string into MPPT2.

To avoid clipping the panels used for East and West should not be with a higher current than 11A. North can be even 650W/17A panels.

6 minutes ago, Scorp007 said:

 

Yes you can use only 1 MPPT but not for the 3 strings you mention. East and West in parallel into MPPT1 as long as the combined current is not over 22A. Then the North string into MPPT2.

To avoid clipping the panels used for East and West should not be with a higher current than 11A. North can be even 650W/17A panels.

Thank you. I have a odd orientation hence wanting to use 3 strings but I'm confused. My largest roof space face's west so I could do 10 panels in series to 1 mppt on this and get sun from 11am to late afternoon. 

My other roofs face direct north and south. The south roof is small but I was outside at 7am and it had good sun. Could I do a 2P5S North, South split here into the other mppt? 

I assume because each orientation is in parallel that once the South string is in shade that it will not affect the output of the North string? 

Or could I do 2 parallel strings with 6 North and 4 South? 

12 hours ago, Chris_S said:

Thank you. I have a odd orientation hence wanting to use 3 strings but I'm confused. My largest roof space face's west so I could do 10 panels in series to 1 mppt on this and get sun from 11am to late afternoon. 

My other roofs face direct north and south. The south roof is small but I was outside at 7am and it had good sun. Could I do a 2P5S North, South split here into the other mppt? 

I assume because each orientation is in parallel that once the South string is in shade that it will not affect the output of the North string? 

Or could I do 2 parallel strings with 6 North and 4 South? 

To say you can or not do 10 in series one would need the Voc of the panels and also the Imp for them.

When using the 10 rather do a 5 string north in parallel with the 5 string south. Although you have sun in summer at 07h00 in winter they might just sit idle. As long as these strings have the same number of panels in series it's fine. 6 North in parallel with 4 south is a no go. Reason is the 6 will be operating at the voltage of the 4 south so you wasting 2 panels year round.