Adding NW facing panels to my current Huawei (with optimizers) setup

[DXT_LT]

Hi,

Was looking for other threads discussing this but could not find. Please point me if you see that I missed a relevant one.

My current setup (installed 3y ago):

• Huawei SUN2000-12KTL-M2 (set up to accept 13.2 kW. but this is rarely reached)
• Modbus integration to Home Assistant (turning on additional load when have lots of solar)
• roof angle is around 30°
• 35 Panels Canadian Solar CS3L-375MS (13.125 kW total):
  • 2 strings (17 and 18 panels).
  • Each String connected to one MPPT (with one pair of DC cables)):
  • Each panel has its own Huawei Optimiser.
  • most face SE. 1 panel faces east'ish. 2 panels face west'ish

• In the image below you can see the pannels
  • Red outline is for the NW roof
  • Orange are chimneys
  • Green is a Solar hot water heater (vacuum tubes)

Last year this setup produced 13035 kWh and met my expectations,
but did not meet my needs

Now to the grand Idea

• the NW facing roof has enough area to fit 25 panels.
• The inverter has a secondary connector on each MPPT for a parallel string.
• I have already a third pair of (unused) DC cables ran from inverter to the roof (had some other ideas ).
• Worked on some Online shade calculators and see that I could expect panels to perform at around 60% on this roof.

What if I installed one more string on this NW roof, and parallelized it with the 17 panel string on it's MPPT?
These panels could also all have their optimizers if it is needed. Especially given that currently all panels have them.
In winter during the day we can have -15°C (but usually most panels are covered with snow).
Also October-March very few irradiance on NW roof

So would it be feasible to install such a parallel string on the same system. how do I size it? should panels be the same model?

• this parallel string option would be cheapest in my case.
• one more could be changing the inverter to accept more strings (sell current inverter). But I can think of several problems.
  • Should be Huawei because of all of the optimizers...
  • Could only find 30KW Huawei inverter with more than 2 MPPT (which is also pricey).
  • if different inverter manufacturer I would have to remove all the optimizers?
• There is of course an option to put a standalone setup for the NW roof.

Looking at all of these options while keeping in mind that the gains would be smaller than normally (due to the NW direction of the roof).

Please share your thoughts.

as a side note. Besides more kWh I hope to have a bit better generation distribution through the day:

 

[zenniz]

Take note that Huawei optimizer has this design limitation, you can only use 1 string per MPPT if you have optimizer installed.

This means that for SUN2000-12KTL-M2 (2 MPPT, 2 input per MPPT), you can't connect anymore strings based on your existing setup.
But you can connect up to 10kW worth of module per string with optimizer or up to 35 modules (So long as sum of DC capacity is less than 10kW) with optimizer per string.
This means that you can connect up to 26 pcs of Canadian Solar CS3L-375MS per string.

Also take note that the max input DC capacity of SUN2000-12KTL-M2 is 18kWp, meaning you can only connect up to 48 pcs of Canadian Solar CS3L-375MS in total but do expect to experience a lot of clipping loss due to overloading.

 

[DXT_LT]

@zenniz Thank you for your insights.

I hope understand what you said correctly. I don't want to disassemble my current system. And I would need to do that, if I wanted to "insert" NW panels into the same string. Because just connecting them to additional MPPT port would mean they are parallel. So it sort of turns my attention to other options.

I just found out that an incentive program started in my country for battery installations. And upon analysing some datasheets and manuals I see a fourth option that includes a battery (which could help me to properly shift excessive power to later hours (to utilise or feed back to grid).
I have a limit of 10 kW to feed back to the grid. Right now my Home Assistant helps me utilize those 3 additional kW by increasing the load in the house. But I hope I could store that excessive energy on the battery and utilise or feed it to the grid in the evening.

I am thinking of adding a new hybrid inverter based system with NW facing panels. Like Solis S6-EH3P15K-H. In this datasheet I see an interesting claim:

• Intelligent AC coupling scheme, easily upgrade existing grid-connected systems

on the instruction I see the diagram and settings:




Which leads me to think that this new inverter could ingest my current grid-tied Huawei based generation.

But the way the settings are described worries me. Looks like in this setup the Huawei system would only work to feed the battery. When the battery is full the system will restrict the output power of Huawei to 0.
Can someone confirm that if set up this way my Huawei system ganerated power would not be fed back to the grid? used just to load the Battery?

My current system is capable to generate up to 90 kWh on a good summer day I wont be able to get this kind of battery

or maybe there is an option to discharge battery to the grid in parallel? Not sure if this is healthy to the battery though...

Any insights would be appreciated

 

[zenniz]

SUN2000-12KTL-M2 does not have any connection port for the battery to be connected directly to the inverter. Also the inverter does not have any built-in communication features to talk to the battery. Your battery setup will need to be AC coupled to your common power distribution board meaning you will need a power conversion unit and a very expensive third party energy management system to synergize the charging and discharging instruction between power conversion unit/battery and the inverter.

To avoid all these complication, I suggest you to get another inverter for your NW roof that have all the built in features for battery.