Hi all. 

I'm connecting my Deye 12kw 3 phase inverter 

What does it mean 2+1 MPP tracker?

It has 2 independent MPPTs
The one MPPT allows for two strings with a max input of 26A the second MPPT can accept 1 string limited to 13A.

Edited February 24, 20224 yr by zsde

Thank you 

So I currently have 16 455w pannels in banks of 8 which I was going to connect into pv1 and pv2 should I put them both on pv1 and leave pv2 available if I add more panels?

Thats what I would do. That leaves you PV2 for another string with maybe different orientation. I assume all your current panels are orientated in the same direction.

Yes they all are 

No issue then to put your two strings on MPPT1 and leave MPPT2 for future expansion. 

On 2022/02/25 at 8:07 AM, zsde said:

No issue then to put your two strings on MPPT1 and leave MPPT2 for future expansion. 

If the panels are in a different orientation should you put it on a different MPPT?

What happens to amps and VOC if you put two strings on MPPT1? Do you add them or is it independent?

Edited November 13, 20223 yr by Milan188

I am also curious why the one MPPT can take two strings, does it parallel them internally ? 

Plus 1 on if the one MPPT with 2 strings can be different directions.

35 minutes ago, Dylboy said:

I am also curious why the one MPPT can take two strings, does it parallel them internally ? 

Plus 1 on if the one MPPT with 2 strings can be different directions.

As long as the Vmp is the same on say a east and west string as well as the same current you can connect them to 1 MPPT. Just ensure total current is not more than MPPT max current or the MPPT will throttle at its max level.

1 hour ago, Milan188 said:

If the panels are in a different orientation should you put it on a different MPPT?

If panels are different orientation and your Inverter has two MPPT, then the ideal is to connect each of these strings to it's own MPPT. 
 

 

34 minutes ago, Dylboy said:

I am also curious why the one MPPT can take two strings, does it parallel them internally ?

Some inverters have two MC4 connections for the same MPPT, and yes, they are paralleled right after the input connectors. 
 

 

35 minutes ago, Dylboy said:

Plus 1 on if the one MPPT with 2 strings can be different directions.

Never ideal to parallel two strings with different orientation as there will be inherent losses. It will work but it's much more efficient to do paralleling with strings with the same orientation. Thats why Inverters with two MPPT should be used when having to contend with different orientation.

Aweosme thanks for the info all.

I always do put different orientations on seperate MPPTs but this 2 strings in one MPPT is cool and if the conformation of my understanding below from previous reaponse is true then this opens up a few more options when it comes to installations.

So then to make sure I'm on the same page...

We can have a East and West on the MPPT with 2 inputs as they paralleled them but as long as the Vmppt and Imppt are the same. ?

IF that is the case then if we have 1 MPPT can we then do the same of 2 strings of same ratings but opposite orientation but Parallel them then it's ok ? 

 

 

Edited November 13, 20223 yr by Dylboy

1 hour ago, zsde said:

Never ideal to parallel two strings with different orientation as there will be inherent losses. It will work but it's much more efficient to do paralleling with strings with the same orientation. Thats why Inverters with two MPPT should be used when having to contend with different orientation.

Why are there losses if it is done like this?

 

1 hour ago, Scorp007 said:

As long as the Vmp is the same on say a east and west string as well as the same current you can connect them to 1 MPPT. Just ensure total current is not more than MPPT max current or the MPPT will throttle at its max level.

Should I add the amps of the two strings together to check the max current or is it the max amps for each string?

Edited November 13, 20223 yr by Milan188

1 hour ago, Milan188 said:

Why are there losses if it is done like this?

 

Should I add the amps of the two strings together to check the max current or is it the max amps for each string?

If you have say a east and west in parallel bothe would be within about 15% of each other on the volts side. In midday the current will be the same. Early the east will have high current while west will have low current.

One just adds the Imp of the panels together to get the peak current in the 11h to 14h time period. Thus if there is throttling it will be during the peak period. Morning and afternoon no throttling should take place.

East West string will produce about 25% less than say a North facing string if they at the same angle.

4 hours ago, Scorp007 said:

If you have say a east and west in parallel bothe would be within about 15% of each other on the volts side. In midday the current will be the same. Early the east will have high current while west will have low current.

One just adds the Imp of the panels together to get the peak current in the 11h to 14h time period. Thus if there is throttling it will be during the peak period. Morning and afternoon no throttling should take place.

East West string will produce about 25% less than say a North facing string if they at the same angle.

I understand the losses with having an east/west array compared to a north facing string. 

For the MPPTs: If I connect both strings to MPPT1 and each string produces a current of 14amps, will the current be clipped to 13amps each because the max current for the 12KW Inverter on MPPT1 is 26amps?

Edited November 13, 20223 yr by Milan188

7 minutes ago, Milan188 said:

I understand the losses with having an east/west array compared to a north facing string. 

For the MPPTs: If I connect both strings to MPPT1 and each string produces a current of 14amps, will the current be clipped to 13amps each because the max current for the 12KW Inverter on MPPT1 is 26amps?

Being in parallel the voltage stays the same but the current adds up. Thus with each string at 14A it means the panels can generate 28A but the inverter can only accept 26A.Thus about 2A is lost.

The current would be 14A if both strings would have been in series as 1 string. This however would exceed the Voc of the inverter for 1 string.

Having said this in Gauteng we normally only get short bursts of the max amps the panels can provide. 80-90% is a good average on good days. Yes at times one can get over 100% for some short bursts. This is based on what I found on my system over 3.5yrs.

3 hours ago, Scorp007 said:

Being in parallel the voltage stays the same but the current adds up. Thus with each string at 14A it means the panels can generate 28A but the inverter can only accept 26A.Thus about 2A is lost.

The current would be 14A if both strings would have been in series as 1 string. This however would exceed the Voc of the inverter for 1 string.

Having said this in Gauteng we normally only get short bursts of the max amps the panels can provide. 80-90% is a good average on good days. Yes at times one can get over 100% for some short bursts. This is based on what I found on my system over 3.5yrs.

Thank you for the explanation. I think I will keep my panels on separate MPPTs and just swap them so that the north one is on MPPT1.

On 2022/11/13 at 11:48 AM, zsde said:

Never ideal to parallel two strings with different orientation as there will be inherent losses. It will work but it's much more efficient to do paralleling with strings with the same orientation. Thats why Inverters with two MPPT should be used when having to contend with different orientation.

How about paralleling two strings with different number of panels? Im planning a setup with 23 panels, 15 mounted on roof and 8 on balcony, all facing same direction, although the angle of roof is 2 degrees less when compared to balcony mounting brackets. Considering my options on 2+1 MPPT inverter I have either 7+8 and 8 (separate connections for roof and balcony) or 8+8 and 7 (mixed connections)

1 hour ago, zellb said:

How about paralleling two strings with different number of panels? Im planning a setup with 23 panels, 15 mounted on roof and 8 on balcony, all facing same direction, although the angle of roof is 2 degrees less when compared to balcony mounting brackets. Considering my options on 2+1 MPPT inverter I have either 7+8 and 8 (separate connections for roof and balcony) or 8+8 and 7 (mixed connections)

The strings should have the same Voltage (or very close) to place them in parallel, ie. you could do two strings of 8  in parallel on the 1st MPPT with 2 inputs, and put the other 7 panels on the single-input MPPT. But not mix a string of 8 and 7 in parallel.

If the panels are facing generally in the same direction it should be fine, and a 2-degree difference in angle will not make a significant difference to the panel Voltage. Otherwise drop a panel and put 7+7 in parallel on the roof if in doubt.

9 hours ago, zellb said:

How about paralleling two strings with different number of panels? Im planning a setup with 23 panels, 15 mounted on roof and 8 on balcony, all facing same direction, although the angle of roof is 2 degrees less when compared to balcony mounting brackets. Considering my options on 2+1 MPPT inverter I have either 7+8 and 8 (separate connections for roof and balcony) or 8+8 and 7 (mixed connections)

The reply from @GreenFields would be the efficient way to connect your 3 strings to a 2+1 MPPT.

8+8 to 1 MPPT and 7 to 2 MPPT should be fine.