Solax X1 G4 Hybrid Inverter with DIY eGolf Powerwall

[Alibro]

Hi guys

If you have been following my EV conversion you may remember a couple of years ago I bought a second eGolf battery pack. I only needed a couple of the modules from this pack for my EV so I had a lot of modules waiting for a new project.
Well this is it!
In early 2022 I had Solar panels installed by a professional company. They installed a 4kW array with a Solaredge 3.68kW inverter (the max I was allowed to export without applying for a bigger export) and a Solar iBoost controller to give us hot water. This setup has worked perfectly since then but things change and I now have an MG5 EV as well as my Freelander conversion so have switched to a cheaper night time tariff and I wanted to use the batteries from the 2nd eGolf pack as a powerwall.
I wasn't sure what the best plan was to integrate with my current setup or even if it would be possible to use another inverter along side it but eventually plumped for a Solax X1 G4 5kW Hybrid Inverter which I bought cheap on Ebay even though it was brand new in box. I wanted to be able to charge the Freelander (it only has a 3kW charger) and run the house at the same time so I figured the 5kW inverter would work for this plus there are times we have cooker, kettle and other stuff running so 5kW was the minimum that could cope with such loads. It might not cover everything 100% of the time but I have no intention of going off grid so it's a fair compromise.
This is the inverter mounted in my garage

And here the battery modules are mounted and partially connected

My plan was to use it to charge the batteries using night time cheap electricity and run the house off it during the day but I wasn't sure what would happen with the excess power from the panels and how it would work with the Solar iBoost controller. The current sensors for the iboost and the inverter are now beside each other and as best I can tell they seem to be sharing the power from the solar panels and I don't think much if any is being exported. At least not since it was installed as the weather has not been that sunny.
From a financial point of view it doesn't matter much anyway as my export income is similar to the night time tariff at around 15p per kWh.
If you're in England on Octopus you will probably pay half that but sadly there is little competition here and the price for leccy in NI is stupidly high.
If anyone is concerned I have the export function of the Solax inverter turned off to prevent the leccy board from complaining. It would only be worth exporting if the night tariff was more than the export income anyway.
For now I have no BMS for this pack so am keeping the max voltage low at 3.9V per cell and min voltage at 3.6V per cell and will monitor the cell voltages to ensure none of the cells get out of balance. Hopefully I'll be able to sort a BMS soon.
For this reason I have to run the inverter in Lead Acid mode which is not ideal but should be OK with the voltages being somewhat conservative.

So I still need to monitor the setup and confirm how it will work long term but for now it seems to be working well. I am completely new to Solax inverters so if anyone has any tips or advise please share.
It would also be nice to install some solar for this inverter to save on the night time charging but that is for another day.

[Alibro]

So today I noticed something a bit odd.
We had a fair bit of sun today and it looks like the water heater is taking the lions share of production with just a few watts going into the batteries. However when the water was at full temp I was hoping to see the spare power going into the battery but instead it just continued taking 50 or 60 watts and I presume the remainder went to the grid. It wasn't until I rebooted the Soleredge inverter that the Solax started using the solar power to charge the batteries.
I suspect for most days this won't matter as the battery will be fully charged every morning and shouldn't need the solar but I thought it would be nice if it worked.
This evening I was charging my Freelander from the Solax batteries but noticed when I stopped charging that the Solax still had over a kW being drawn which confused me as the house shouldn't have been drawing anything like that. Turned out the water heater was running so it must have thought the panels were generating. Once I turned it off and on it stopped taking power but this is something I need to watch.

I guess it's hardly surprising the two systems are getting a bit confused.

[Alibro]

Another cause of confusion has been the RCBO tripping several times over the last week. I had an electrician install a 32A socket for it and had assumed he would use a 32A but no. It was 16A so hardly surprising it tripped with a 20A load!
When I checked the way it was installed I realised he had used a single 2.5mm T&E cable for the socket. I'm not an electrician so I don't know if that would be sufficient for a 32A socket but Decided to upgrade by running a second 2.5mm T&E cable as if it was a ring main. It may not make any difference but made me happier doing it, and as I was connecting the cable in I realised the RCBO was only 16A so a 32A unit is on order.

[Alibro]

It looks like I may have an issue with the Solax inverter getting into a hung state.
If the solar panels are generating through the Solaredge and I turn on the Solax, it recognises power being exported and diverts it to charge the batteries so at this point all is well.
The problem I'm seeing is in the morning after charging the car overnight. When I went to the Solax this morning the panels were generating 1.5kW but the Solax was only putting 50W into the batteries even though they were below max voltage. After resetting the Solax it started charging the batteries at 1kW so something had become confused. I still need to confirm if it will power the house when in this state.
I've seen this behaviour a few times so I need to figure out why it is doing it and if it will sort itself out without needing reset.

[muehlpower]

I have a system with 2 Solax X3 G4 inverters and a triple power battery. Everything works as it should for me. Have you set the charging and discharging times correctly?

[Alibro]

I have a system with 2 Solax X3 G4 inverters and a triple power battery. Everything works as it should for me. Have you set the charging and discharging times correctly?

Thanks for the reply
I think so, Forced charge time starts at 02:00 and ends 08:00
Discharge starts at 08:01 and ends 01:59

It seems to charge OK but like I said sometimes gets into a funny state where there is solar being exported to the grid from the Solaredge inverter and it's not until I reset the Solax that it grabs that power and puts it into the battery. I need to confirm what will happen if I don't intervene. I'll keep an eye on this and report back.

One other thing I need to sort is a BMS for the 60S battery and preferably one that the Solax will play nicely with.

[muehlpower]

Why do you use charge/discharge times? I have only set priority self-consumption.

[Alibro]

The price I pay for night time is similar to the price I receive for export so it is better to have the battery fully charged every morning.
Also many days my Solar is not sufficient to charge the battery fully.
The cheaper electricity is from 1am to 8am in the winter and 2am to 9am in the summer, so to save me having to change it twice a year I set it to charge from 2am to 8am.

[muehlpower]

Your discharge time is over midnight, or the end time is less than the start time. Have you tried splitting it up from 8:00 to 23:59 and 00:00 to 1:59?

[Alibro]

I see what you mean.
I'll set the discharge to end at 23:59 then use the 2nd charge discharge option to start discharge from 00:01 until 01:59 and see if that works.
If not I'll just forget about 00:00 to 02:00 as there will be very little drain then anyway.
Thanks for the suggestion.

[Alibro]

Another couple of days and the two inverters plus the water heater seem to be playing nice together.
One of the issues I had was the MCB installed by the electrician was only 16A so when the Solax tried to draw or send 5kW it tripped. I think I was getting confused by this and the fact the Solax will only send 50 or 60W to the batteries when they are nearly charged.
So I changed the MCB to a 32A version and this morning I had Hot water from the morning solar and a full battery and this afternoon I'm topping up my Freelander partly from the battery and partly from solar.

[Alibro]

Good news, I think the issues are sorted and it seems to be working perfectly by feeding the house all day with plenty to spare. I can even add 5 or 6 kWh to my Freelander from the battery pack (I don't have a timer for the Freelander charger to charge it overnight) or heat the hot water tank without emptying the battery although I need to see how well this will work in the winter with little or no solar.
I think the issues I was seeing were down to a couple of things. The electrician had fitted a 16A MCB instead of 32A so when the house was drawing 5kW and sometimes during charging at night, it tripped but this wasn't obvious as the inverter still had power from the battery. The only message on the screen to indicate loss of power was "Idle" which I didn't understand at first. Once I replaced the MCB this stopped. Also it looks like once the forced charging phase has completed it will trickle charge at 50W or so until the voltage drops before taking anything from the solar. I'm not sure what the voltage drop needs to be but probably a couple of volts. Today I put a few kWh into the Freelander and immediately after it started taking 800W from the solar.
It looks like the solar is going into the battery before heating the water but I always knew that might happen and it is easy to boost the hot water if necessary. It does mean some losses in the conversion from ac to dc then back to ac again but I'm not too concerned, it's still a similar price to using oil to heat the water and much better for the environment.

Hopefully things are a wee bit safer now I've added a 25A fuse and contactor to the middle of the pack and a box to cover the modules is in production.

I'm just waiting for an emergency off button so I can kill the output from the pack easily by cutting the 12V to the contactor. It's a 300A contactor so should easily be able to cut the DC current in an emergency. If there was a runaway condition drawing loads of current then the 25A fuse will blow. I also plan to build a wooden cover for the pack today to make it safer.

I guess the big take away from all this is not only will the Solax inverter play nicely with the pre-installed Solaredge inverter but will even sense when the solar is being exported and route the power into the batteries without the solar panels needing to be connected to it.
It does kinda override the Solar iboost water heater but that is not really a problem.

[Alibro]

The box is pretty much sorted now.

x

[tom91]

Nice fire risk. I hope your garage is not attached or built into your house. You could at least have used some materials that would appear to be fire retardant, not that a lithium fire would really be stopped by anything just contained for a little while.

I doubt any insure would touch this if the worst were to happen.

Have you check on your cell balance recently? How far are you from installing a BMS?

[Alibro]

Nice fire risk. I hope your garage is not attached or built into your house. You could at least have used some materials that would appear to be fire retardant, not that a lithium fire would really be stopped by anything just contained for a little while.

I doubt any insure would touch this if the worst were to happen.

Have you check on your cell balance recently? How far are you from installing a BMS?

The balance was good last week. The modules all came from a car with only 10k miles, the current is at most 25A, the max full charge cell voltage is 3.95V and minimum discharge cell voltage is 3.5V.
No it's not ideal running without a BMS but I'm not overly worried and am hoping to have it sorted soon.