Greetings fellow solar experts,

I would like clarification regarding the Max PV (DC) input on the DEYE 5KW inverter.
My current setup is:
4 x 550W JA solar panels on MPPT1
8 x 550W JA solar panels on MPPT2

The 4-panel string is east-facing and sits around 180-190V depending on solar output.
The 8-panel string is west-facing and sits around 360 - 370V depending on the solar output.

Total installed PV power is 6600W (obviously under ideal conditions and assuming that all panels get the same amount of sun)
Due to the East/West setup, I probably won't ever get the total 6600W. The max that I've seen was around 5KWh on a good sunny day.

I believe that the JA Solar 550W panels have a rating of 42V at around 13A. 

====================================

My question relates to overspeccing on the solar panels to ensure that I have plenty of solar power during bad weather.
From my understanding, can the inverter only process a max of 6500W of PV power?

My current PV setup is 6600W (theoretical max) which is just about the max of the inverter.
Would it be possible to add another 4 x 550W panels on the east-facing string? 
This should result in a theoretical max of 8800W PV power, with around 360-370V for each of the  MPPT controllers.
During bad weather, and let's say 50% solar efficiency, the max PV power will be 4400W, which probably would be fine.

What will happen during good sunny weather?
Since both MPPT controllers are under the 450V string limit, will the inverter only draw the max of 6500W even if more PV power is available?

Will the inverter balance the Amps being drawn between the 2 MPPT's to the point where it keeps the PV power under 6500W ?

Thanks in advance and looking forward to hearing from the community.

Edited April 4, 20242 yr by Niel Kotze

51 minutes ago, Niel Kotze said:

Greetings fellow solar experts,

I would like clarification regarding the Max PV (DC) input on the DEYE 5KW inverter.
My current setup is:
4 x 550W JA solar panels on MPPT1
8 x 550W JA solar panels on MPPT2

The 4-panel string is east-facing and sits around 180-190V depending on solar output.
The 8-panel string is west-facing and sits around 360 - 370V depending on the solar output.

Total installed PV power is 6600W (obviously under ideal conditions and assuming that all panels get the same amount of sun)
Due to the East/West setup, I probably won't ever get the total 6600W. The max that I've seen was around 5KWh on a good sunny day.

I believe that the JA Solar 550W panels have a rating of 42V at around 13A. 

====================================

My question relates to overspeccing on the solar panels to ensure that I have plenty of solar power during bad weather.
From my understanding, can the inverter only process a max of 6500W of PV power?

My current PV setup is 6600W (theoretical max) which is just about the max of the inverter.
Would it be possible to add another 4 x 550W panels on the east-facing string? 
This should result in a theoretical max of 8800W PV power, with around 360-370V per both MPPT controllers.
During bad weather, and let's say 50% solar efficiency, the max PV power will be 4400W, which probably would be fine.

What will happen during good sunny weather?
Since both MPPT controllers are under the 450V string limit, will the inverter only draw the max of 6500W even if more PV power is available?

Will the inverter balance the Amps being drawn between the 2 MPPT's to the point where it keeps the PV power under 6500W ?

Thanks in advance and looking forward to hearing from the community.

I would not full knowingly that you exceed the maximum do it. It is a 5500W inverter and 6600W is already a overspec. Should it be known what you have connected I would not honour the warranty. Thus the risk is yours. 

Each MPPT is a separate controller and should not balance between them. Logic normally should prevail.

Edited April 4, 20242 yr by Scorp007
Corrected my statement of adding 4 panels to the wrong MPPT

Little sense in adding more panels. The peak AC output is 5kW no matter what panels are connected. The 6500W DC output is only useful if you've got batteries charging from that solar.

Look out for a plaque on the side of the 5kW Deye inverter that indicates a maximum of 3250W per MPPT. Don't know if the newer models have it, but mine does.

If so, I'd rather consider six panels per side, and considering that the loss due to the East or West orientation is in the order of 15%, so in reality your inverter will be in spec.

I know folks over-panel to help against low sun, but bad weather will drop your solar output to 20% of rated power, maybe less.

 

1 hour ago, Scorp007 said:

I would not full knowingly that you exceed the maximum do it. It is a 5500W inverter and 6600W is already a overspec

The official specs of the DEYE 5KW inverter:
5KW max AC output
6.5KW max DC (PV) input

I am currently within / pretty much on the limit of the DC input, at least based on the theoretical maximum output of my panels.
Due to my root setup, I can only point 4 panels east but have space for 8 west-facing panels, hence connecting a 4 panel string to one MPPT and 8 panels to the other MPPT.

If each MPPT can only handle 1/2 of the total DC (PV) input of 6500W, they each should be able to handle 3250W,  assuming that they operate independently.
Yes I understand that the 8 x 550W west-facing string is in theory 4400W max (under ideal solar conditions in a north-facing setup), which would exceed the 3200W limit of each MPPT. In reality, on a sunny day, due to west-facing panels, I don't get the full 4400W potential output of the 8 x 550W panel string.

In regards to the 5KW AC load, I have never exceeded that limit. The max AC load that I've pulled was around 4.5KW.

If each MPPT is limited to handling 3250W each (adding up to 6500W), then my question is slightly different.
During the day, after my batteries are fully charged and my SmartLoad has heated the geyser, my typical AC load is around 500W.
During this 500W load, the inverter / MPPT controller(s) appear to control the amount of power from the panels (based on the load) by manipulating the current.
From my monitoring directly on the inverter, I can see that the PV voltage stays the same at 190-ish Volt and 370-ish Volt during strong sunlight but the Amp is greatly reduced.

I guess I was hoping that the same would happen if there if PV output (Watts) exceeded 6500W while the PV string voltages were with spec.

1 hour ago, GreenFields said:

Little sense in adding more panels. The peak AC output is 5kW no matter what panels are connected. The 6500W DC output is only useful if you've got batteries charging from that solar.

Look out for a plaque on the side of the 5kW Deye inverter that indicates a maximum of 3250W per MPPT. Don't know if the newer models have it, but mine does.

If so, I'd rather consider six panels per side, and considering that the loss due to the East or West orientation is in the order of 15%, so in reality your inverter will be in spec.

I know folks over-panel to help against low sun, but bad weather will drop your solar output to 20% of rated power, maybe less.

 

Hi. Just to clarify:
I don't need nor use the full 5KW AC output of the inverter.
The intention of adding 4 more panels to the existing 4 x 550W east-facing string was due to the string only running at around 190V where 370V is achievable, and getting more PV output to overcome the panel inefficiency during bad weather.

My east-facing roof only has space for 4 panels, hence why I put those 4 panels in a string.
My west-facing roof has space for 8 panels (and more), hence why it has an 8-panel string. 

Assuming that each MPPT controller has a max of 3250W, and the inefficiency of east-west panels setup, I was hoping that I could push 4400W per string and still be in spec. During winter / bad weather 4400W per MPPT would not be a problem but in good sun it could be.

Perhaps 7 panels per string would be safer?
7 x 550W (per string) = 3850W (max) 
3850W (max) minus 15% east-west efficiency loss = 3272W ........... very close to spec.
3850W (max per string)  x 2 = 7700W
7700W minus 15% east-west efficiency loss = 6545W .......... very close to spec.

Just trying to max out the setup without overloading it !
 

6 hours ago, Niel Kotze said:

Hi. Just to clarify:
I don't need nor use the full 5KW AC output of the inverter.
The intention of adding 4 more panels to the existing 4 x 550W east-facing string was due to the string only running at around 190V where 370V is achievable, and getting more PV output to overcome the panel inefficiency during bad weather.

My east-facing roof only has space for 4 panels, hence why I put those 4 panels in a string.
My west-facing roof has space for 8 panels (and more), hence why it has an 8-panel string. 

Assuming that each MPPT controller has a max of 3250W, and the inefficiency of east-west panels setup, I was hoping that I could push 4400W per string and still be in spec. During winter / bad weather 4400W per MPPT would not be a problem but in good sun it could be.

Perhaps 7 panels per string would be safer?
7 x 550W (per string) = 3850W (max) 
3850W (max) minus 15% east-west efficiency loss = 3272W ........... very close to spec.
3850W (max per string)  x 2 = 7700W
7700W minus 15% east-west efficiency loss = 6545W .......... very close to spec.

Just trying to max out the setup without overloading it !
 

As long as you stay within the MPPT specs you can oversize as much as you want , just remember everything over 5kw is DC to DC only so if your batteries are full that power wont be produced. My array is 7,3kwp east west split on 5kw Sunsynk if i wanted to i could easily add 2 more panels but there is no more roof space. East west split production falls off pretty steeply in cape town winters.  

6 hours ago, Niel Kotze said:

Perhaps 7 panels per string would be safer?
7 x 550W (per string) = 3850W (max) 
3850W (max) minus 15% east-west efficiency loss = 3272W ........... very close to spec.
3850W (max per string)  x 2 = 7700W
7700W minus 15% east-west efficiency loss = 6545W .......... very close to spec.

Just trying to max out the setup without overloading it !
 

When we mention efficiency loss we mean over the course of a day. Early/later in the day you have a few hours where each string would produce at maximum and it's in these periods that you will get more power from the 8 panel string into its MPPT where you have the risk. Thus one cannot reduce the total Watts by 15%.

Also as @GreenFields mentioned during bad cloudy days you can easily get only 10-20% of the Watts from the panels so to try and counter this is normally not possible. For these days one would use a generator to supplement. Most times not practical to try and counter it for the bag PV days. Each MPPT must operate at any time within it's own 3250W maximum to be safe. 

 

10 hours ago, Scorp007 said:

I would not full knowingly that you exceed the maximum do it. It is a 5500W inverter and 6600W is already a overspec. Should it be known what you have connected I would not honour the warranty. Thus the risk is yours. 

Each MPPT is a separate controller and should not balance between them. Logic normally should prevail.

That is not correct @Scorp007 it is very common to "over watt" the panels, especially as panels are getting so cheap, as long as the voltage is below the max, the MPPT controls how much power it accepts from the panels and will not accept more than it wants. 

I had 12.7kw on my 8kw without any issue and all Ok's by Sunsynk. 

The MPPT's are both controlled and will both be throttled if there is no where for the inverter to send the power.

Max DC power on the 5kw is 6500W, so that is the maximum amount of DC power that the inverter will accept from the panels assuming that it has somewhere to send the power.

Main reason for over-watting the panels is to still get production on low solar radiation days. 

Good video from Keith at Sunsynk on the topic

 

8 hours ago, Niel Kotze said:

In regards to the 5KW AC load, I have never exceeded that limit. The max AC load that I've pulled was around 4.5KW.

If each MPPT is limited to handling 3250W each (adding up to 6500W), then my question is slightly different.
During the day, after my batteries are fully charged and my SmartLoad has heated the geyser, my typical AC load is around 500W.
During this 500W load, the inverter / MPPT controller(s) appear to control the amount of power from the panels (based on the load) by manipulating the current.
From my monitoring directly on the inverter, I can see that the PV voltage stays the same at 190-ish Volt and 370-ish Volt during strong sunlight but the Amp is greatly reduced.

I guess I was hoping that the same would happen if there if PV output (Watts) exceeded 6500W while the PV string voltages were with spec.

Hi @Niel Kotze

You can pull more than 5kw from the inverter as long as the grid is up at the time. The inverter will pull the power above 5kw from the grid up to a maximum of 35A (Max Passthru in specs) or 8050w @ 230v

Only the amperage can be throttled by the MPPT, not the voltage, that is why it is important not to go over voltage.  

Max Power from each MPPT depends on the voltage of the strings, max amperage it will accept is 13A, MPPT range is 150-425V, assuming you are getting 425V from the string the max power per mppt would be 5525W, the MPPT's will however be throttled to a combined max DC power from the panels of 6500W 

It is also important to keep in mind that PV Panel voltage is inversely proportional to the panel temperature, so the voltage goes up when it gets colder. If you are close to the limit on warm days you could very well be into the smoke/fire territory when it is very cold.  A PV voltage of around 400V is safe. 

32 minutes ago, Sc00bs said:

That is not correct @Scorp007 it is very common to "over watt" the panels, especially as panels are getting so cheap, as long as the voltage is below the max, the MPPT controls how much power it accepts from the panels and will not accept more than it wants. 

I had 12.7kw on my 8kw without any issue and all Ok's by Sunsynk. 

The MPPT's are both controlled and will both be throttled if there is no where for the inverter to send the power.

Max DC power on the 5kw is 6500W, so that is the maximum amount of DC power that the inverter will accept from the panels assuming that it has somewhere to send the power.

Main reason for over-watting the panels is to still get production on low solar radiation days. 

Good video from Keith at Sunsynk on the topic

 

Thank you for the reply ScOObs.
The video explains it very well and it goes along with my supposed expected way how a MPPT controls the wattage.
From my monitoring, I noticed that the current (Amps) fluctuates based on the load that the inverter need.
The video demonstrates that the MPPT  changes the resistance of the string, which in turn controls how much current can flow.

So as long as my panel string voltage is within spec, the MPPT will limit the current (Amps) and thus restrict the Wattage of the string to a maximum of 3250W?
My 8-panel string produces a max of around 370V (as displayed by the inverter's displayed output screen).
So worst case scenario, I waste potential solar output on a good sunny day.

39 minutes ago, Sc00bs said:

You can pull more than 5kw from the inverter as long as the grid is up at the time. The inverter will pull the power above 5kw from the grid up to a maximum of 35A (Max Passthru in specs) or 8050w @ 230v

Only the amperage can be throttled by the MPPT, not the voltage, that is why it is important not to go over voltage.  

Max Power from each MPPT depends on the voltage of the strings, max amperage it will accept is 13A, MPPT range is 150-425V, assuming you are getting 425V from the string the max power per mppt would be 5525W, the MPPT's will however be throttled to a combined max DC power from the panels of 6500W 

It is also important to keep in mind that PV Panel voltage is inversely proportional to the panel temperature, so the voltage goes up when it gets colder. If you are close to the limit on warm days you could very well be into the smoke/fire territory when it is very cold.  A PV voltage of around 400V is safe. 

Thank you for your reply.
An 8-panel string with my JA panels typically end up giving 360-370V.
As you pointed out PV voltage go up when the panels are cold.
Not sure how much the voltage can increase but I assume that 370V should be safe as that is well below 425V ?

5 minutes ago, Niel Kotze said:

Thank you for your reply.
An 8-panel string with my JA panels typically end up giving 360-370V.
As you pointed out PV voltage go up when the panels are cold.
Not sure how much the voltage can increase but I assume that 370V should be safe as that is well below 425V ?

Yes, not going to increase that much. 

You can check in your panels specs but is usually around 0.3%/C increase in VOC, 

19 minutes ago, Niel Kotze said:

Thank you for the reply ScOObs.
The video explains it very well and it goes along with my supposed expected way how a MPPT controls the wattage.
From my monitoring, I noticed that the current (Amps) fluctuates based on the load that the inverter need.
The video demonstrates that the MPPT  changes the resistance of the string, which in turn controls how much current can flow.

So as long as my panel string voltage is within spec, the MPPT will limit the current (Amps) and thus restrict the Wattage of the string to a maximum of 3250W?
My 8-panel string produces a max of around 370V (as displayed by the inverter's displayed output screen).
So worst case scenario, I waste potential solar output on a good sunny day.

If your voltage is 370V, the max amperage the MPPT will accept is 13Av (JA Solar 555W panels are 13.1A I think) so the max power from that string is 370V x 13A = 4810W

5 minutes ago, Sc00bs said:

If your voltage is 370V, the max amperage the MPPT will accept is 13Av (JA Solar 555W panels are 13.1A I think) so the max power from that string is 370V x 13A = 4810W

Yes, that sounds about right. 
My east/west-facing panels don't get the raw output that north-facing panels get.
From my testing, the main benefit of east/west panels is getting more solar output early on and later in the day.
I get very decent power, even at 8 am. This morning, my 4-panel string already produced 800W, even that early.
I don't get the huge during midday though. I suspect that the angle of the midday sun on the east-west panels limits their output.

Speaking of Amperage:
I don't recall my inverter ever going over 10A on the MPPT, probably due to the east-west panel setup.

18 minutes ago, Sc00bs said:

Yes, not going to increase that much. 

You can check in your panels specs but is usually around 0.3%/C increase in VOC, 

Cool thanks - It does not get *that cold* where I live during the day when the sun is out.
I'm in the Cape near the ocean. A cold winter day here might be 10 degrees Celcius.

In that case, I think I can safely run a 8 panel string per MPPT and waste solar output on a sunny day !

I have done some testing today. At around 10:40 am with random clouds, I was getting 2.4KWh - 3KWh from the east and west panels combined.
PV voltage on the east-facing 4-panel string was 185V while the 8-panel string facing west (barely getting decent sun at 10:40 am) was generating 353V.

I don't have any more roof space facing east, but I figured that could mount 4 more panels facing west but add them to the 4-panel string that faces east.
Since I get so much power from the west-facing string, even early morning, I can benefit from 4 more facing west but connected to the east-facing string.
That should boost my morning and overall solar output.

@Sc00bs

Thanks for the video. It was not meant as a Sunsynk specific reply with respect to the maximum current. I know that some inverters if you over panel too much and the current exceeds the maximum when starting up the inverter will just shut down to protect the MPPT or for whatever reason. 

It would not be enjoyable to fit the panels and then find you forced to remove some. 

Thus take it personally I would not input 4810W into each MPPT when there is a label on the inverter to limit PV to 3250W. Because panels are cheap is not enough reason to exceed spec. May be I am just too conservative. 

@Niel Kotze That voltage on the west side does not mean anything during the morning. Watts available would depend on the current that can be produced on the west panels. Also of not much use to check now. See what the west side could produce in winter during the morning period.

I would like to see yields in winter of a East-West series string. 

Edited April 5, 20242 yr by Scorp007

43 minutes ago, Niel Kotze said:

I have done some testing today. At around 10:40 am with random clouds, I was getting 2.4KWh - 3KWh from the east and west panels combined.
PV voltage on the east-facing 4-panel string was 185V while the 8-panel string facing west (barely getting decent sun at 10:40 am) was generating 353V.

I don't have any more roof space facing east, but I figured that could mount 4 more panels facing west but add them to the 4-panel string that faces east.
Since I get so much power from the west-facing string, even early morning, I can benefit from 4 more facing west but connected to the east-facing string.
That should boost my morning and overall solar output.

Be careful with the idea to connect West-facing panels to East-facing panels. You're likely to either cut production if in series, or exceed the current in put in parallel, and either way be disappointed. Maybe think about adding 4 panels through a micro-inverter.

13 minutes ago, Scorp007 said:

Thanks for the video. It was not meant as a Sunsynk specific reply with respect to the maximum current. I know that some inverters if you over panel too much and the current exceeds the maximum when starting up the inverter will just shut down to protect the MPPT or for whatever reason. 

It would not be enjoyable to fit the panels and then find you forced to remove some. 

Thus take it personally I would not input 4810W into each MPPT when there is a label on the inverter to limit PV to 3250W. Because panels are cheap is not enough reason to exceed spec. May be I am just too conservative. 

I fully understand your approach, not wanting to blow up your inverter 🙂
My inverter label does not state the limit per MPPT but only a global max of 6500W.

Going on the specs on the label on my inverter:
PV Input Volage: 370V
PV Input Current: 13A (DC) + 13A (DC) 

If you use the specs that DEYE provides and multiply the 370V with 13A, you end up with a 4810W  (per MPPT)
This is more than the 1/2 of the 6500W total max. Not sure how those numbers add up if they are provided by DEYE.

5 minutes ago, Niel Kotze said:

I fully understand your approach, not wanting to blow up your inverter 🙂
My inverter label does not state the limit per MPPT but only a global max of 6500W.

Going on the specs on the label on my inverter:
PV Input Volage: 370V
PV Input Current: 13A (DC) + 13A (DC) 

If you use the specs that DEYE provides and multiply the 370V with 13A, you end up with a 4810W  (per MPPT)
This is more than the 1/2 of the 6500W total max. Not sure how those numbers add up if they are provided by DEYE.

It's very easy to see how they add up. You can use panels of 80W and use 3 string in parallel being about 13A.Then you do another set and connect in series. Then another one in series. So you can go on as long as the total series does not exceed the 450V or whatever. 

You can also use 50V panels of say 500W of 9 in series. This below 450V. Nowhere does it say you can connect panels of 13Ax450V=5850W per MPPT. These values are the maximum for volts OR Amps. 

15 minutes ago, GreenFields said:

Be careful with the idea to connect West-facing panels to East-facing panels. You're likely to either cut production if in series, or exceed the current in put in parallel, and either way be disappointed. Maybe think about adding 4 panels through a micro-inverter.

Thanks for the information.
It is my understanding that panel voltage adds up. Unless a panel in a string is faulty and breaks the flow of power, adding more panels should add more volts to the string.
Shading on a single panel in the string would also cause issues but that is not a problem in my setup as there are no trees in sight.

I don't have much experience with micro inverters nor how they would interface with my existing inverter.

4 minutes ago, Scorp007 said:

These values are the maximum for volts OR Amps. 

I'm not sure if OR applies. 
VOC is a critical value that may not be exceeded as that will damage the inverter.
Perhaps the inverter can use a max of 450V but will then limit the current to 7.2A. This will keep the wattage within spec.
(450V x 7.2A = 3250W)

Assuming that the PV input voltage is below the max VOC, the MPPT controller will reduce the Amps to stay within the 3250W spec?

11 minutes ago, Niel Kotze said:

Thanks for the information.
It is my understanding that panel voltage adds up. Unless a panel in a string is faulty and breaks the flow of power, adding more panels should add more volts to the string.
Shading on a single panel in the string would also cause issues but that is not a problem in my setup as there are no trees in sight.

I don't have much experience with micro inverters nor how they would interface with my existing inverter.

Yes you are right it adds up. That's why I added a number of series panels as per my 80W post to get up to the 120V start voltage. 

Seeing voltage under low amps on panels does not mean it will stay high when you start loading them and they must produce the amps and amps cannot be produced under low irradiation. 

Yes it will stay within the 3250W as the MPPT will not use more as per the video on a previous reply. 

Not 13Ax370V per MPPT. 

Edited April 5, 20242 yr by Scorp007

30 minutes ago, GreenFields said:

Be careful with the idea to connect West-facing panels to East-facing panels. You're likely to either cut production if in series, or exceed the current in put in parallel, and either way be disappointed. Maybe think about adding 4 panels through a micro-inverter.

"or exceed the current in put in parallel". 
I have 2 x series strings, each connected to their own MPPT. No parallel connection in my case.

2 minutes ago, Scorp007 said:

Yes it will stay within the 3250W as the MPPT will not use more as per the video on a previous reply. 

I don't expect more than 6500W total PV power 🙂
I suppose the dream is to have 6500W available solar power from sunrise to sunset.