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Help understanding panel sizing capacity for Conext MPPT 100-600

Right now I'm considering:
  • 6 @ SOK Battery | 100Ah 48v | 5.12 kWh = 30.72 kWh
  • 3 @ Trophy | 48V220E-1 48/51.2 Volts, 220 Amp | 11.26 kWh = 33.78 kWh
  • 3-4 @ KiloVault HAB V4 7.5kWh | 48V/150A | 7.5kWh = 22.5 kWh - 30 kWh *Most expensive but closed loop
I don't think I'm ready for the maintenance and setup of FLA, Flooded, GEL, AGM. Was considering EG4, but some users reported compatibility issues with the XW.

When looking at the batteries, check the recommended discharge current vs the current you will need to drive your inverter. Some of the server rack batteries have a really low recommended discharge current.

I have not looked up the batteries you are considering but here is an example of the problem:
The EG4s recommend a whopping 30A as the discharge current! The spec also says it can run a 100A discharge..... but I have never heard an explanation of the recommended 30A vs the 100A.... so I would be hesitant to run them at 100A. For a 6KW inverter, you would need to be able to provide ~140A continuously. This means you would need *five* EG4 batteries to keep it under 30A.

Note: Several of us have asked @RichardFromEG4 about the 30A recommendation several times. In fact, it was discussed on a thread with him in the last day or so. Unfortunately, he has not gotten an answer from the engineering team yet.
 
When looking at the batteries, check the recommended discharge current vs the current you will need to drive your inverter. Some of the server rack batteries have a really low recommended discharge current.

I have not looked up the batteries you are considering but here is an example of the problem:
The EG4s recommend a whopping 30A as the discharge current! The spec also says it can run a 100A discharge..... but I have never heard an explanation of the recommended 30A vs the 100A.... so I would be hesitant to run them at 100A. For a 6KW inverter, you would need to be able to provide ~140A continuously. This means you would need *five* EG4 batteries to keep it under 30A.

Note: Several of us have asked @RichardFromEG4 about the 30A recommendation several times. In fact, it was discussed on a thread with him in the last day or so. Unfortunately, he has not gotten an answer from the engineering team yet.

I just looked up the trophy battery and it does not seem to have a low recommended discharge rate. It seems to be specified at 200A
 
When looking at the batteries, check the recommended discharge current vs the current you will need to drive your inverter. Some of the server rack batteries have a really low recommended discharge current.

I have not looked up the batteries you are considering but here is an example of the problem:
The EG4s recommend a whopping 30A as the discharge current! The spec also says it can run a 100A discharge..... but I have never heard an explanation of the recommended 30A vs the 100A.... so I would be hesitant to run them at 100A. For a 6KW inverter, you would need to be able to provide ~140A continuously. This means you would need *five* EG4 batteries to keep it under 30A.

Note: Several of us have asked @RichardFromEG4 about the 30A recommendation several times. In fact, it was discussed on a thread with him in the last day or so. Unfortunately, he has not gotten an answer from the engineering team yet.
YES, 30A discharge limit, would be very disappointing. We have three EG4 LLs, which would be fairly useless for the intended application, if that is something the BMS would limit, forget, if the LLs also state this limit.

Thanks to you, @FilterGuy, and others, who were asking for answers!

(For a different off grid location, here, we also have Trophy 48V220E-1s ... Hoping that they have no surprises) Thanks again, POD
 
Note: Several of us have asked @RichardFromEG4 about the 30A recommendation several times. In fact, it was discussed on a thread with him in the last day or so. Unfortunately, he has not gotten an answer from the engineering team yet.
Yes, I have messaged them 2 times previously about this. I don't know if you've ever worked with China but they tend to ignore questions frequently and selectively answer others. I'll send another ping.
 
@pvdude and @FilterGuy. At the moment I'll be doing just 1 @ MPPT 100 600 with a PV of 2s1p generating a total of 427.12V @ 24.34A for maximum 7,680kWh - 8,400kWh (w/ bi gain).

Eventually I'll be expanding to 12k. In that regard:
  • Can I put a different size array in the second MPPT 100 600 for example 12 PV total instead of the 16 PV that I'm planning now for the first MPPT? Or should both controllers preferred have the same array size (V/A/W)?
 
Can I put a different size array in the second MPPT 100 600 for example 12 PV total instead of the 16 PV that I'm planning now for the first MPPT? Or should both controllers preferred have the same array size (V/A/W)?
you can put different arrays on each controller.
 
I just looked up the trophy battery and it does not seem to have a low recommended discharge rate. It seems to be specified at 200A
Thank you very much for your input.

For my planed Grid-Tied 6K system consisting of:
  • 16 PV - Q-Cell (XL-G10-480BF) / 24V 480W (525W with bi) / Voc 53.39V @ Isc 12.17
    • Config: 8S1P generating a total of 427.12V @ 24.34A for maximum 7,680kWh - 8,400kWh (w/ bi gain).
  • 1 @ XW 6848 PRO
  • 1 @ MPPT 100A 600V (max 550 VDC @ 35A) w/ up to 8.5kW for overpanel.
  • 1 @ Full XW PDP
  • Rapid Disconnect w/ TIGO's (TS4-A-F)
Which of these 2 batteries setups will you recommend (specs bellow)?
  • 30.7 kWh = 6 @ SOK Battery | 100Ah 48v | 5.12 kWh = 30.72 kWh *Open Loop
  • 22.5 kWh = 3 @ KiloVault HAB V4 | 7.5kWh | 48V/150A | 7.5kWh = 22.5 kWh *Closed loop
The KV HAB V4 system is $2.5k more than SOK for less capacity, but it's closed loop and UL certified.

Just in case, In PR the current NEC code is 2017. I was told UL is not required for the batt backup, just Inverter and PV/Parts.

1658174302659.png
 
Hi Great Discussion - Closed loop certainly is the best way to go. Have you looked at Discover batteries too? They are closed loop.

I'm also planning a similar setup of 16 Q cells in two strings of 8 with the Schneider 100-600 controller / 6848 Inverter.

However the smaller G11 panels which fit nicely on our roof only have a NOCT Vmp of 29.4 V, which makes the voltage of a string of 8 panels only 236 V.

236 V is within the 195 V to 510 V controller MPPT operating range but I've heard that to optimize power transfer the operating voltage for the Schneider 100-600 should be over 250 volts. Anyone know if this is the case? The controller specs and manual don't go into this.

Also - does the sketch below show appropriate breaker protection design for 6,400 W of PV in two strings?

2023-02-21 15_57_48-Window.png
 
236 V is within the 195 V to 510 V controller MPPT operating range but I've heard that to optimize power transfer the operating voltage for the Schneider 100-600 should be over 250 volts. Anyone know if this is the case? The controller specs and manual don't go into this.
I have not heard this.... but that does not mean much. Having said that, Schnider does a good job of documenting their gear so if it isn't mentioned in the manual it probably is not an issue.

Also - does the sketch below show appropriate breaker protection design for 6,400 W of PV in two strings?
Fusing is not required for one (or two) parallel strings, but

1) The wires (as shown) are considered PV input circuits in the NEC and they should be sized for 1.56 x ISC = 1.56 x 13.5 = 21.06A
2) If the two strings combine before the charge controller, after they are combined they are considered PV output circuits. The PV output circuit must be sized for 1.56 x Isc x Number of strings = 1.56 x 13.5 x 2 = 42.12A.
3) You still need a disconnect that breaks both the positive and negative lines. Some people use breakers as the disconnect and that is fine but I would size them for 1.75 X ISC (or greater) to avoid any nuisance pops.

You may be wondering where "1.56" came from.... for more information, please review this resource:


The set-up with the DIN rail terminal strips is interesting, but I would discourage it unless you were running some kind of experiment that needed precise measurements of each panel voltage. (The current is going to be the same everywhere in the string so you can measure that anywhere.) The reason I discourage it for any kind of normal installation is that solar arrays are somewhat infamous for having problems in one of the many connections between the panels. Adding in all those DIN rail blocks just makes it worse.

If there really is a need to measure the voltage of each panel, go for it. However, you should just expect that adding all that wiring and all those connections through the terminal blocks is going to be a problem.

BTW: If you decide to go ahead with the terminal blocks here are a few tips to help avoid the problems.

1) Either be sure to use terminal blocks rated for stranded wire or use ferrules on the wires.
2) The terminal blocks are part of the PV input circuit and must be rated for 21.06A or greater. (ISCx1.56)
3) The terminal blocks need to have connections rated for the size wire you are using. (10AWG)
4) Be sure to use terminal blocks that are rated for something greater than the array Voc. (325VDC)
5) Wire it up and torque each terminal screw to spec. Then wait at least 3 days (preferably with a reasonable temp variation from night to day) and then torque them all to spec again. DIN rail terminal blocks have a reputation for the connection 'relaxing' in the first several days. Some folks blame in on heat expansion/contraction and others blame it on the wires settling in. No matter what the reason, you don't want to take a chance when running that much current through the tiny little DIN terminal blocks
 
The set-up with the DIN rail terminal strips is interesting, but I would discourage it unless you were running some kind of experiment that needed precise measurements of each panel voltage. (The current is going to be the same everywhere in the string so you can measure that anywhere.)

If one opened the breakers and jumpered the exposed individual panel circuit legs to short them one by one, it would be possible to check and measure Isc for each panel from inside the box with the jumper and then Voc without the jumper. The practical problem with this is that unless all of the panels are disconnected one would be working in places at a high DC voltage of up to 325 volts relative to ground. That is probably not a good idea when up on a metal roof.

Although my experience with high voltage extends to working with testing designs for 150,000 VDC capacitor banks to power UV Excimer lasers in a plasma physics lab - HV can be scary even with most everything immersed in a high dielectric strength oil bath. The oil surface at 150 kV becomes a fountain wherever a sharp corner extends into the oil, it polarizes and gets accelerated by the field strength. You should have heard the noise whenever something failed and we had an air breakdown.

Thanks for the excellent observations and design tips on required ampacities and breaker sizes!

By the way for the OP: Rolls now also has LiFePO4 batteries that do closed loop with the Schneider system.
 
have not heard this.... but that does not mean much. Having said that, Schnider does a good job of documenting their gear so if it isn't mentioned in the manual it probably is not an issue.

Well documented indeed but a little hard to understand sometimes.

After digging deeper into the MPPT specs and operating manual I found that that the Schneider 100-600 MPPT does not turn on until 230 V (drops out of operation if voltage falls to 195 V) and does not output 100% power until around 255 V.

So a good idea to design Vmp/V0c string voltages to be as high as possible, while keeping below 600V to avoid the lower voltage output power drop-offs and cutout voltage.

That said, I'm still not sure what the optimum operating voltages might be for each of 24 V or 48 V systems as they don't state that in the manual.

MPPT-100-600-Specs3.png

MPPT-100-600-Specs.png

MPPT-100-600-Specs2.png
 
That said, I'm still not sure what the optimum operating voltages might be for each of 24 V or 48 V systems as they don't state that in the manual.
For the most part, the battery voltage does not matter when it comes to the PV voltage on an MPPT. An MPPT operates pretty much independently of the battery voltage.

The exception to this (that does not apply to your case) is that some MPPT controllers will operate with the PV voltage pretty close to the battery voltage. In most (all?) of these controllers, there will be a spec that says the PV voltage must be X volts above the battery voltage. Usually, this is 3 to 5 volts.
 
After some research and help from members of this forum I've decided to start with a 6k Grid-Tie system and expand to 12kWh within 12-18 months. For the inverter I'll be choosing the Schneider Conext XW 6848 with the full Conext PDP as I plan to expand. Battery size will be 20-30kWh but still haven't decide on brand (SOK, Trophy or KiloVault HAB V4 7.5 because UL listing).

If you are thinking of using the KiloVault HAB batteries because of their closed loop connectivity with Schneider gear you should read this thread by an upset user (an experienced electronics engineer) that indicates that the Kilovault SOC closed loop implementation doesn't fully work with Schneider equipment:

"KiloVault Battery, is it good?"

Other closed loop LiFePO4 battery options for Schneider include Fortress, Discover, Rolls, Pylontech, BYD and EG4. I've heard good things about the first two but am not at all familar with the others.
 
Hello

I have a question about the Schneider Conext MPPT 100 600 6kW Solar PV Charge Controller
is the 550Volt and the 35Amp the total for two strings or for each of the two strings?

Thanks Scat
 
Hello

I have a question about the Schneider Conext MPPT 100 600 6kW Solar PV Charge Controller
is the 550Volt and the 35Amp the total for two strings or for each of the two strings?

Thanks Scat
I’d think it is for the total as the charge controller has only one channel.

There are actually three wire terminal connection points, but they are all on the same bus bar, all leading into the same single circuit.
 
Thanks for the pointer POD. You are correct! I was assuming 150V @ 60A based on some specs I found online.

With the correct specs, I still could do 16 PV instead of 14 PV for:
  • 4 series of 2 PV of 53.39V = 106.78V @ 11.12A = 960W connected in parallel which will bring the total array to 8 PV = 106.78V @ 44.48A = 3,840W / 4,200W (with bi gain).
  • With 2 MPPT 60-150 in the same configuration I could get a total of 7,680W-8,400W (with bi gain). without exceeding the Max PV array rating of 5,250 W for each MPPT.
That will give me the full XW 6,848k and between 832W-1,552W (with bi gain) for over panel.

Looking at the Pro/Cons for going into 2-4 smaller MPPT 60 150 instead of 1-2 larger MPPT 100 600 I found:
  • Power consumption, night time: 2.5 W vs < 1 W
  • Supported battery types: (Flooded, GEL, AGM, Custom) vs (Flooded, GEL, AGM, Lithium-ion, Custom)
After all considerations, I think I'll setup around the MPPT 100 600. Found another SE Technical document detailing that the 100/600 can go up to 8.5kWh in over panneling:

View attachment 102843
@scuba_pr I got the same panels and charge controller (Conext MPPT 100-600). I don't quite follow
  • 4 series of 2 PV of 53.39V = 106.78V @ 11.12A = 960W connected in parallel which will bring the total array to 8 PV
can I just connect 8 panels in series, and then parallel them? Also please give an update on how you feel about this configuration after in use?

Thanks.
 
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