How do I best use the 2+1 MPPT from the DEYE 12KW?

the_german · Mar 14, 2024

Hello community.
I was away for a long time and a few weeks ago I swapped my 3x Axpert 7200 for a Deye 12kw 3-phase hybrid inverter, which I want to use as an island system with a network bypass via the generator input. Netzparallel is not possible for legal reasons.
Technically, I largely understand how to install the device, but the 2+1 MPPT confuses me.

So far I had 6 MPPTs from the 3 devices and the modules were relatively evenly distributed across all MPPTs. The fact that the 6 areas do not all receive full sun at the same time or are shaded differently was a very useful solution.

To make it easier for those reading along, I'll include the values of my PV modules and the values of the inverter.

Max power 230w +/-3%
Max voltage 29.7V
Max current 7.75A
Open circuit voltage 37.2V
Short circuit current 8.3A

I have 46 modules spread over 3 roofs
18x PV field 1 (2x9)
14x PV field 2 (2x7)
14x PV field 3 (2x7)
I can change the fields to 1x18,14,14 without much effort.

The DEYE can handle a maximum of 15600W, which I can't reach because the modules are already 15 years old and together they would only be 13600W.
The MPPT range is 200V-650V (start voltage 160V)
MPPT1 has 2 inputs with a total of 26A (34A Max.PV ISC)
MPPT2 has 1 input with 13A (17A Max.PV ISC)

My question is. Can I use MPPT1 (2 inputs) with 2 different voltages, e.g. use 14 and 18 modules or does the voltage have to be approximately the same? And how will the MPPT behave because each of the 3 possible fields is in the sun or is shaded at different times.

I would be grateful for a few suggestions.

denmek · Mar 26, 2024

Hi, the best is of course 18 x PV to MPPT 2 and Field 2& 3 parallel on MPPT1, pls use junction box with fuses for combining the PV fields.

houseofancients · Mar 27, 2024

the_german said:
Hello community.
I was away for a long time and a few weeks ago I swapped my 3x Axpert 7200 for a Deye 12kw 3-phase hybrid inverter, which I want to use as an island system with a network bypass via the generator input. Netzparallel is not possible for legal reasons.
Technically, I largely understand how to install the device, but the 2+1 MPPT confuses me.

So far I had 6 MPPTs from the 3 devices and the modules were relatively evenly distributed across all MPPTs. The fact that the 6 areas do not all receive full sun at the same time or are shaded differently was a very useful solution.

To make it easier for those reading along, I'll include the values of my PV modules and the values of the inverter.

Max power 230w +/-3%
Max voltage 29.7V
Max current 7.75A
Open circuit voltage 37.2V
Short circuit current 8.3A

I have 46 modules spread over 3 roofs
18x PV field 1 (2x9)
14x PV field 2 (2x7)
14x PV field 3 (2x7)
I can change the fields to 1x18,14,14 without much effort.

The DEYE can handle a maximum of 15600W, which I can't reach because the modules are already 15 years old and together they would only be 13600W.
The MPPT range is 200V-650V (start voltage 160V)
MPPT1 has 2 inputs with a total of 26A (34A Max.PV ISC)
MPPT2 has 1 input with 13A (17A Max.PV ISC)

My question is. Can I use MPPT1 (2 inputs) with 2 different voltages, e.g. use 14 and 18 modules or does the voltage have to be approximately the same? And how will the MPPT behave because each of the 3 possible fields is in the sun or is shaded at different times.

I would be grateful for a few suggestions.

You did the exact same swap as I did, although I went with the sunsynk version

Mppt 1 is parallel over 2 mc4 connections.
Panels connected to these should be as close as possible in amps and VOC.

Mppt 2 is a seperate mppt ( with lower amps) so you can put another string here of different voltage and amps to mppt1

I would try to max out the mppt1 in voltage as much as you can, but do give yourself 50v playroom.
That means you can get to 600v max on your strings, and still have a 60v safety margin.

As to amps, you can go over the max amps per mppt1 by about 20% , safely, this is called overpaneling.
In full sun that means the inverter will pull the max amps the mppt's are rated for, but in cloudy weather ( in Germany just as bad as here in the Netherlands) you will get more in comming power

shadowmaker · Mar 27, 2024

Going above 650V on MPPTs seems to be ok as my setup is usually sitting at 650-750V (stay under max 800V) and production is very good. Every panel set with different sun direction (azimuth) should be connected to only one MPPT to get best outcome. So even if you can parallel two strings into MPPT 1, production will suffer some if those arrays don't get the "same" sun.

You should use as high PV string voltage as possible while staying under 800V all the time. 18S x 37,2Voc makes 669,6V so you should be fine even with -35C.

You can use different string voltages for your two inputs on MPPT1, but it will hurt production. Ideally they should have identical voltages with both arrays facing identical sun direction and tilt.

Quattrohead · Mar 27, 2024

You can leave them exactly as they are and just wire them into the new inverter, they are perfect as is.

How do I best use the 2+1 MPPT from the DEYE 12KW?

the_german

New Member

denmek

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houseofancients

Solar Wizard

shadowmaker

Solar Addict

Quattrohead

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