question

Juraj Nikolov avatar image
Juraj Nikolov asked

comparing mppt multiplus II GX vs easySolar II

I have a question which ones of solution is better and if it is necessary to solve it or nor.
1) multiplus II GX 5kva
3x mppt 150/35 bluetooth ; (optoinal + 2x mppt 150/35 bluetooth)
victron ET340 (it is necessary ?)
4x pylontech U3000C
12x 500wp mono panels (3stings of 2series x 2parallel) 6kwp ; (optional + 8 panels and 2strings of 2series x 2parallel together 10kwp)

It is possible to connect 5strings in to GX ?

2) easysolar 5kva (gx+250/100) (optoinal 2x mppt 150/35 bluetooth)
victron ET340 (it is necessary ?)
4x pylontech U3000C
12x 500wp mono panels (1stings of 4series x 3paraller) 6kwp ; (optional +8 panels and 2strings of 2series x 2parallel together 10kwp)


A solution with three strings occurred me to because in the afternoon I have on the roof of the shadows from another house. See picture. roof.jpgAnd whether it would not result in a reduction in performance, when it was in one string (mppt 250/100).The question is if the mppts 150/35 will by charge the battery well, or better as 250/100.


Subquestion:
My house is feeded from grid 3-phase, but I want one phase use to plug to the multiplus II(easysolar II) and have this phase as a backup (for appliances), which I would like to use in the evening from the battery and during the day from the sun, plus the surplus sent to the grid. It is this possible ?

Or I want to much ?

Lot of thanks for help.

Juraj




Multiplus-IIEasySolar All-in-Onesetup
roof.jpg (5.0 MiB)
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

3 Answers
ejrossouw avatar image
ejrossouw answered ·

@Juraj Nikolov Worth reading the ESS document on the Victron website as it will be explain much of your sub question. Yes it can do what you want.

As for which system, it much depends on the space you have and whether you will use VE.Direct or VE.Can connections for the MPPTs. On a GX you can add one VE.Direct MPPT before having to use a VE.Direct to USB dongle or USB hub and dongles. Neither has VE.Can if you considered using VE.Can on the MPPT.

Have a play with the calculator to explore some string options as it will also take temperature into account which is very important. https://www.victronenergy.com/mppt-calculator I'd personally do 3 x strings of four and while the 250/100 can handle 5800W, make sure VOC is not exceed at any time.

Hope this helps to do you planning.

3 comments
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Juraj Nikolov avatar image Juraj Nikolov commented ·

Hi tanks for reply.


Regarding mppt when using 150/35 I can only go via VE.Direct, here I have a question that if I wanted to extend the system with additional strings I would need this cable?

1649057853535.png

And run it through a USB hub that is powered by its own source. From what I've seen on the GX cebro, 15 devices can be connected via VE.direct, which is enough for me.


Even with regard to strings, these parameters have string:

1649059250127.png

If I connect the strings in parallel, the voltage remains and the current is calculated on the busbar. Wit three strings, the voltage will be 119V but the current 105A,

I need still have to clarify this part, maybe I'll find it somewhere in the description of ESS how it works.

I did not find in the documentation how several mppts controllers communicate with each other and how they charge the batteries. Maybe I didn't find the right documentation.

I read this.

DVCC manage it ok, but I don't how, and what a current I will be on the busbar. For example due to fuses for batteries, etc.

https://www.victronenergy.com/media/pg/Cerbo_GX/en/dvcc---distributed-voltage-and-current-control.html

https://www.victronenergy.com/live/ess:start


Thanks.





0 Likes 0 ·
1649057853535.png (120.5 KiB)
1649059250127.png (94.3 KiB)
ejrossouw avatar image ejrossouw Juraj Nikolov commented ·
Yes that is the cable and indeed a self powered USB hub. Worth checking the forums on the USB hubs as there has been some mixed success with different hubs.You should consider using a 6 or 10mm2 PV cable for such a long run as you should not exceed a voltage drop of more than 3V for the string. NOTE - Don't confuse the MPPT output with the panel's VOC/ISC as the MPPT output is 48V/35A in your example.

PS - Some more homework for you when you look up the Smartnetwork document on the Victron website which explain when to use it , limitations and how it works. Prior to that MPPT were simply connected together as is much the case when combining multiple chargers and they individually then charge to the parameter they were configured with.

0 Likes 0 ·
Juraj Nikolov avatar image Juraj Nikolov ejrossouw commented ·

It's this document :)

"https://www.victronenergy.com/upload/documents/Manual-VE.Smart-Networking-EN.pdf"

If yes so great :)

So if I connect the pylontechs to the GX cebro, it will control it practically on its own and in ideal conditions as one big regulator "Each unit will (and should) regulate its own output current" but each mppt regulator must be configured the same and it "should" work :)

This was the information I needed to know, I don't have to solve the algorithm as it does:)) BIG THANKS ;)


As for the cables, I calculated from 6mm2, it should hold out 50A, those 35A will be on that cable often and I think the 4mm2 cable is up to 30A.
The length of the longest string should be max. 15 meters, plus cables on the panels, I estimate those at 4 max. 6 meters. When I give a reserve let it be 25m for the longest string.
The second string should be about 3-4 meters shorter, so 21m
The third string will be max 17m.
I guess I'll have those strings of shorter length.
I will have to measure length and resistance properly and then add up, but I think that 6mm2 could be enough.

I take Isc and Voc as input to mppt foreign max 119.2V and 35A, output should be those 48V and 35A.

I still want to ask, if I can.
How is solved the safety for distribution network technicians when they repair transformer, for example?
How does multiplus find out that it should not send overflows to the network when there will be a technological shutdown of the network? I would not like to harm anyone's health or life.
For example if I use ET340. If it find out that there is no voltage \ current on phase one, so it automatically stops supplying power to the grid?
Do you know some elecrical scheme (or document) which describes how it works ?

Thanks.
Juraj

0 Likes 0 ·
Juraj Nikolov avatar image
Juraj Nikolov answered ·

6x-mppt-100-20-48v-5520wp.jpg (971.2 KiB)
1649251027093.png (3.2 MiB)
1 comment
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

shaneyake avatar image shaneyake commented ·

The voltage from the panels is way to high for the MPPTs, they will be destroyed. 100/20 has a MAX voltage of 100V, if you go over it will damage the MPPT. For those panels with 50VOC, it cold weather they will output more than 50V. You can use this tool from Victron to pick the right MPPT.

https://www.victronenergy.com/mppt-calculator

You are missing the VE.Direct or VE.CAN cables that need to go to each MPPT. Bluetooth won't work in this use case.

0 Likes 0 ·
bella-swan avatar image
bella-swan answered ·

The Multiplus-II-GX (And Easysolar-II-GX) have a built-in board. This is essentially a small ARM computer. All the GX devices are. But the one in the MP-II-GX is based on a quad core 1.2Ghz Nanopi which is the fastest platform of all 4. The Cerbo is the next fastest, followed by the Venux-GX and then the CCGX.

So unless the built-in GX option costs significantly more than the external one, I'd encourage you to go for it.

There is one exception though: If you want to use the fancy analog/digital connections on the Venus-GX/Cerbo-GX, then obviously you have to go for the discrete solution. Also, a Venus-GX has two built-in relays. For the average guy running a residential setup, it makes little difference. Go with what makes the most sense to you.

5 comments
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Juraj Nikolov avatar image Juraj Nikolov commented ·

@bella-swan


Hi,


the difference in the price of multiplus-GX and multiplus + solo GX is about 80 euros, I calmly sacrifice them if it's faster :)

I would soon need to verify that it is possible to connect and control via bluetooth mppt controllers. I try to read the manuals and many of the forums for the help of at least directing me to the manual (documentation).

But honestly, the documentation is very alibi-written: D

For example in this documentation:

https://www.victronenergy.com/upload/documents/Manual-VE.Smart-Networking-EN.pdf


In the third part of the writing, it is possible to connect smartSolarChargre together via VE.SmartNetwork and recommend the use of GX, that pleased me :)

But in part 5 they write that Ve.SmartNetvork is designed for small systems that do not have a GX module.

OK I don't consider my proposed system to be big :))


And now it's essential:

"In systems which the GX device is used "for logging purposes only," VE.Smart Networking can be used to allow chargers to synchronize, or even receive information from sensors."

What is meant by the purpose logging only ... ??? :))


"Keep in mind that if, for some reason, the same information (ie voltage sense) is being received by the charger over BLE and VE.Can / VE.Direct, the information coming over BLE (through VE.Smart Networking) will be ignore. "

What does it mean to receive information via "BLE":))

BLUETOOTH? : D or what ...


So how it is? It is possible that the mppt controllers will be controlled from the BMS battery via the CAN bus which is connected to the GX and the communication of mppt controllers from the GX will be work via bluetooth ?

I got lost in that documentation :)


With this involvement, I would be able to maximize profits from the panel array, as I do not have a well-oriented building and I have shadows.

I think, this will give me better efficiency, but only if it can charge properly and the regulators will not fight each other.


Sorry I wrote up a bit :)

0 Likes 0 ·
shaneyake avatar image shaneyake Juraj Nikolov commented ·
You can not use Bluetooth in a system like this. Basically if you have a GX device you need to wire all your VE.Direct or VE.CAN MPPTs to the GX. Same for BMS.CAN for battery to GX and same for Inverter to GX all needs to be cabled. Everything except VE.Direct uses cheap CAT5e/CAT6 cable.


I would also rather install a Cerbo than a Multiplus-II GX for the simple fact that it is easier to add and expand a system using the Cerbo. It also has 2x CAN ports, one for Battery and one for VE.CAN which is how the bigger MPPTs communicate. The Cerbo is also the most supported from a software perspective in my option.

0 Likes 0 ·
Show more comments
Juraj Nikolov avatar image Juraj Nikolov Juraj Nikolov commented ·

The BLE is a communication protocol for bluetooth ...

0 Likes 0 ·