OK, so i thought i knew what i was doing, but apparently not. Please help me in victron land

DIY
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1

OK,

So i am going to look like a boob here, but i dont see a great alternative, please give me a pass this one time… :slight_smile:

So i am looking to do something which on the face of is should be very simple, but feels like its becoming increasingly challenging.

I am looking to do:

A grid tied system of of moderate output G98 compliant.

14 panels with a total output max of in theory 4500w (in reality will be far less in this climate) arranged as two 7 panel strings giving 400v per string.

I am not looking to sell back to the grid, merely offset my baseload usage and chare a small battery to give me a little capacity outside of daylight hours. My goals feel very modest, however i have made my life very complicated.

IU have the panels and i have a battery, the battery is a LG Chem Resu 6.4, she is an old girl and giving me some real problems. My original plan was to use a growatt sph6000 as this has can communication and use a can protocol converter to keep the battery happy, however my network operator would not approve the 6000w inverter, so rather than making my life hard i thought i would “simply” get an inverter that will talk to the battery.

This seems to be the MultiPlus 48/3000/35 and this is where i am becoming unravelled. I am sure you guys all get this natively but i am now presented which what seems to be a requirement for about a million expensive blue boxes to actually complete a system. rather than a single hybrid inverter…

This seems counter intuitive, but I am here to learn.

The obvious and simple solution would be to yeet the L|G chem battery, but i am resistant to this as i have it, and where i live getting a replacement will be challenging and selling the LG will be more challenging still, also i am stubborn and want to make it work, well, just because i do.

I want to do this in as cost effective way as possible. for those of you who know this kit well, what additional victron components do i need above the cerbo and MultiPlus 48/3000/35? Obviously MPPT’s but what, and i assume yet another box to act as a combiner?

Why so hard?

Would love any assistance you can offer.

thanks

Iain

2

Hi Iain, based on your comments on the climate and G98, are you somewhere in the UK?

Are you trying to sell power back to the grid? Not sure why the network operator is concerned unless they have a limit.

What are the panels, as the capacity of 4500w in 14 panels seems a bit different - am asking because that 400V 7-panel x 2 strings eliminates certain MPPT options. eg might be worth making a change (eg doing 12 in a 3x4 arrangement to get that voltage down.) or maybe have a look at something like the https://www.victronenergy.com/inverters-chargers/multi-rs-solar

There’s a lot of smarter folks than me here. Welcome aboard!

3

You better sell the LG and ask a local seller what you need, some resellers here in the Netherlands sell complete Victron and battery sets with cable, fuses and so on.

Local grid regulations may limit the choice, the Victron rs 6000 may be a good choice, but may not be sold or used in your country.

As DIY I would avoid the mp series if you have not computer technical and electrical skills.

5

Hi,

Thank for the response, panels are just a generic black panel (yes likely to be less efficient but look better) from memory they are 330w per panel at 56v. The 400v strings is fairly normal for an all in one hybrid inverter like the growatt i had which have an ideal V of 360-400.

I am in the Isle of man, so Same G98/99 regs but completely different authority. I am not exporting to the Grid but the local regs basically don’t permit more than 3.6KW generation, The grid guys came round for a visit and ultimately know its nonsense, but the rules are the rules. I could try and fight it, but its a waste of time and energy. Over here, no means no. Ultimately its of little real world concern to me as i am very unlikely to generate more than 3kw, but its just meant I have had to sell the growatt.

I can change the panel arrangement, but its less optimal and of course seems to mean even more MPPT’s …

Packhorse Lane (Upper) (strings)
Packhorse Lane (Upper) (strings)1280×1280 124 KB

As you can see it would mean either some sore of 2x 3+4 arrangement, or bridging either side of the centre pitch which could mean shadowing at some angles

6

I would rather not do that, i want to understand How i can make best use of what i have. i can use any inverter under 3.4kw my limitation is sending the keep alive CAN signal to the LG which the Multiplus does, but there are other inverter options that i can look at which should run the LG if the victron solution is too cumbersome. But seems like a weird business model, all be it i do see the advantage of modular design, but only to a point.

the rs 6000 looks like it will manage the spec all be its overkill for the panel output and i dont really want to spend 1500 on an MPPT, 400 on the multiplus, 150 on the Cerbo when there are more cost effective options out there.

I have fair mechanical, and technical skills. frequently repair Ev’s etc (last weekends work below)

20250810_180206
20250810_1802061920×1440 1.18 MB

I am however new to Solar, so just need to understand the options

thanks

7

Due to existing equipment, you have kind of limited choices in the Victron enviroment.

LG Resu 6.4 is not the ideal for Victron but still usable, with 3000W Multiplus, as detailed here. For a compact approach use a Multiplus II 3000W GX device.

As a 3000w inverter is kind of small for a house, the ESS system should be used as a support, i.e. all loads on AC IN, most probably you will also need a power meter, like ET112.

Another option is to use AC Out 1 for critical loads and all heavy loads on AC Out 2. This all depends on your usual and peak consumption.

For the MPPT, Victron says no to any CANbus MPPT (don’t know why), use only MPPT’s with VE direct communication. Because of this limitation, a panel label would be of great help in your search on the Victron MPPT calculator.

Using given data, a Bluesolar 250/100-Tr might do the job, but exact panel data should be known so that maximum voltage of 250V is not exceeded in any circumstances.

For DC distribution and fusing you may use a Lynx Power IN.

However, a slightly compact installation can be achieved with only 2 Mega fuse holders, disconnects like “Victron battery switch” and connect both battery and MPPT directly to MP-II, pay attention to cable lugs, it must be perfectly seated !

8

Thank you for this, appreciated.

The bluesolar looks sensible, but realistically i would be looking at 4 panels per mppt given in direct sunlight i am getting close to 56v so in certainn conditions may marginally breach the 250v cap.

To be honest i am thinking I may be barking up the wrong tree here and would be better off just using a solax all in one as that will run the resu 6.4 and will do upto 360v strings on both mppts…

Be nice to use more flexible kit to allow for future changes but not sure the juice is worth the squeeze to be frank

9

I would be interested to hear your reasoning for this. Of course you can use the full lineup of Victron MPPTs (eben non-Victron omed) including those with Canbus

10

@pau1phi11ips If you have not purchsed, I’d propose considering an easysolar all-in-one as not every device is certified so check the DNO register first. The 2400W 3000kVA should be ok, but I would suggest the 5kVA which with the G98 grid code will be manufacturer limited to the 3.68kW, which only requires a G98 notification and can easily be upgraded to G99 by just changing the grid code if 4.4kW is more acceptable. I used a LG RESU10 despite not on the compatibility list which served me very well.

11

Very interesting. I assume the Resu10 has the same keep alive requirement? Looks to use the Same CAN2.0B protocol also.

Did you also used a GX device to manage the CAN communication or was this actually a single box solution?

12

Hi,

Sorry for any misunderstanding, it is not my reason, please have a look on the Victron document related to LG Resu.

13

The document talks about using a CCGX or VenusGX with version 2.15 minimum, which dates it a fair few years back. Possibly before any other GX was released.

These older GX have only one Canbus, so if you switch its protocol to Canbus BMS, no other Canbus device can be used anymore.

Modern GX like the Cerbo and Ekrano come with two Canbus, so you can set one to VE.Can for your MPPTs while the other is set to Canbus BMS for the battery.

DVCC works fine for mixed MPPT communications

14

Thanks for update !

Despite the odd thing regarding CANbus MPPT incompatibility with LG Resu, I did not question the document, being revised June 2025.

15

I used it with a cerbo GX device. It send the CVL etc data. I only moved away from it due to the limit of two units that could be connected together and the keep alive worked as intended.