Solis RHI 6K 48ES 5G Inverter Fox ESS LV5200 Battery - Charging limit ? and export to grid ...

[coolcarper1]

Hi All, just had my Solis 6kw inverter and two Fox LV5200s installed too and noticed exactly the same problem others were having. Charge rate was maxing out at 1300w or 24A, BMS error stating low temp on inverter. Only way of knowing via app appears to be looking at what the charge current limit is.

Just added some insulation around them (rockwool inside insulating bubble wrap) and will see if that does the job over winter months. Hoping the hest generated by the internal resistance of the batteries is enough to get it up to 15c, but hope it won't exceed 30c.

The hest mats might be a better solution in the long term with a modest amount of insulation instead, so if the batteries get hot during the summer months they can still radiate the heat away.

View attachment 124041

This is what I have done and its working well. Some before and after pics and during the warmer months the front panel can be removed.

 

[SeaGal]

Hoping the hest generated by the internal resistance of the batteries is enough to get it up to 15c, but hope it won't exceed 30c.

Welcome!
Fingers crossed, but I only see a 5 degree rise in temp with a fast charge overnight. May need some heat too (though not too much)

 

[Frankie1000]

This is what I have done and its working well. Some before and after pics and during the warmer months the front panel can be removed.

That's perfect, I think the solid construction of the insulation boards is good for moving around as required. I think I'll go down that route when I get chance. I just happened to have some spare rockwool and a roll of insulation bubble wrap.

I've got it set to import tonight during octo go hours and that's at max of 50A so will try check logs in morning to see where we are with charge rates.

It's a little annoying after spending so much on this system that these charge limits are imposed. Would have been nice to be able to tweak the temp parameter as we are fit.

I have a "naked" 5.2kwh self built pack in the garage with a cheap Daly BMS and I'm used to pumping those cells with whatever I can get hold of. I see no issue with 1C charge rates in general but these cold temps we have been seeing has me thinking how safe is it for the cells pushing hard at lower temps? Anyone know of some good papers on LiFePo4 and temperature relationships?

My garage office where that system sits is well insulated but it is frigid right now as im working inside the house most days so may be causing undue stress charging that pack up at 27A at sub zero temps...

I mean, if Fox have deemed it necessary to limit charge rates to 10A (even in parallel as my system is) then there's got to be a reason??? I saw 10A limit just in past hour as it's Baltic up there in loft, and SOC is about 35% so that plays into the charge rate equation too I guess.

Lots of questions and not too many answers!

 

[Frankie1000]

Just a quick update to the insulation hack job (without heaters) and it seems that about two hours into the nightie charging schedule the charge limit shifted up to 100A (just as I had it set to finish at 3am. Shame that it took so long to get there as meant the batteries barely charged last night.

Currently it is sat at 100 charge limit, I might go and test to see if that's actually true by forcing a grid charge as I feel it might shift down again given low SOC.

Will monitor over next few days and see how we end up and will go down heater route if need be.

Also, anyone know about how these packs balance? Do they top balance once full or do they actively balance throughout the charging cycle? If the latter then I see how the BMS might limit charge rate if the cells are somewhat out of balance.

 

[Frankie1000]

Another quick update for anyone who's interested. Just forced charged it at it took pretty much full 100A with ambient loft temp of about 2 or 3c. Seems to have done the trick, but will monitor through the day and see how it shifts as it gets further away from any heat generating charge / discharge cycles.

 

[coolcarper1]

When doing nothing my battery sits at 30a once it receives a charge it goes to 50a and after about 10 mins full at 100a, this is for 2 batteries as I believe you will only get 50a with a single battery

 

[SeaGal]

It's a little annoying after spending so much on this system that these charge limits are imposed. Would have been nice to be able to tweak the temp parameter as we are fit.

That is the nature of LiFePO4 cells, for longevity must not charge below 0 and reduce charge rate below 10 degrees, dependent on SOC.

See my posting here....

Science based discussion on charging LiFePO4 below 32°F

It wouldn't be hard for an engineer designing a BMS to scale charge current with temperature and state of charge. Seems like it could be done in firmware. For example: 10A@-10°C, 15A@-5°C, 20A@0°C, 30A@5°C, 40A@10°C, 100A@20°C. This would allow them to better protect the battery from damage at...

diysolarforum.com

I have a "naked" 5.2kwh self built pack in the garage with a cheap Daly BMS and I'm used to pumping those cells with whatever I can get hold of. I see no issue with 1C charge rates in general but these cold temps we have been seeing has me thinking how safe is it for the cells pushing hard at lower temps? Anyone know of some good papers on LiFePo4 and temperature relationships?

Do not charge at high rates at low temps, especially then above 70% SOC ..See above posting.

Also, this spec from EVE for LF280K cells, is likely to apply similarly to all cells using LFP chemistry.

I mean, if Fox have deemed it necessary to limit charge rates to 10A (even in parallel as my system is) then there's got to be a reason???

YES! Longevity.

 

[SeaGal]

Just a quick update to the insulation hack job (without heaters) and it seems that about two hours into the nightie charging schedule the charge limit shifted up to 100A (just as I had it set to finish at 3am. Shame that it took so long to get there as meant the batteries barely charged last night.

As expected. LFP cells have low internal resistance, so only heat up about 5 degrees for a full charge.

You will need to heat them _before_ charging . Mine have 15W heater, which is keeping them at 20 degrees C with ambient at -3 last night (with 100mm PIR around them)

Also, anyone know about how these packs balance? Do they top balance once full or do they actively balance throughout the charging cycle? If the latter then I see how the BMS might limit charge rate if the cells are somewhat out of balance.

I'm not familiar with FOX ESS ?‍, but it is common for top balancing to take place only during charge and only when cells get to a high-ish voltage (typically around 3.4V).

 

[finalbillybong]

This is what I have done and its working well. Some before and after pics and during the warmer months the front panel can be removed.

I was going to do that (and automate the heating with Home Assistant) but I asked my installer his opinion and he just said he would move everything into a warmer area of my house.

 

[timselectric]

I was going to do that (and automate the heating with Home Assistant) but I asked my installer his opinion and he just said he would move everything into a warmer area of my house.

That's the best option.
All of my equipment (except solar panels, of course) lives in the house with me. And enjoys the same environment that I do.

 

[finalbillybong]

That's the best option.
All of my equipment (except solar panels, of course) lives in the house with me. And enjoys the same environment that I do.

Oh I agree. Now if I could just figure out an issue I'm.having with the batteries discharging past the discharge limit I'll be happy with my system.

 

[Frankie1000]

Hi All,

So ressurecting this a little. I'm pretty sure there is a bit of an issue here but can't be 100% sure, as sunlight has been at a premium these past few days, but I noted that there was light but nothing was going to battery.

System is set to self use with charge between 00:30 and 04:30 (though didn't charge last night as had charge from grid turned off).

So I noted that even as there was sunlight, there was nothing going to battery and the solar number was limited even though house use was low. As soon as it was switched to backup mode, 800+ watts were going into battery. Switching that off and back into self use worked as expected.

It seems it gets confused over night and then just sits there not charging the battery until it is forced.

As far as I can see the only thing on is self use and others are off.

No idea why it's getting stuck and not charging batteries even when there is 600 odd watts of excess over background load?

Note area of graph where I forced it to backup mode then reset it back to self use.

 

[GBRDBRY]

Sorry to have been AWOL from the thread for a while (kitchen remodel before xmas became the priority under direction of the house boss )..

Admiring the insulated environments people have been creating however...

I had decided to push back to the contractors ... and I have just had the Senior installation engineer from ENVOENERGY (who we purchased the system from) here at the house (he drove down from Manchester) after a rather ranty phone conversation from me to their MD...

He confirms 100% they never install in loft spaces, and all training courses, data from battery manufactures etc state this- cold environment being one issue, but accessibility and potential fire hazard being another.

So the BS I was given by the subcontract installers that they "always install in lofts and have never had this issue in 20 years and there must be an issue with Solis " is total sh1t! ...

Basically lazy sub contract installers find it easier, cheaper and faster to make the electrician run a longer cable inside the house from loft to Consumer unit, rather than having to extend the dc cables from panels to inverter outside the house in conduit.
In our case this also had the side effect of him drilling through a soil stack and having to have a plumber round at their cost to repair, with a bathroom out of action for a week ...

He will return himself to move (FOC) both battery and inverter to a downstairs utility space we have right next door to the consumer unit hopefully next week, running DC cables properly outside the house.
Hindsight is great, but this should have been discussed with us at time of install or before.. we had little to no knowledge of the whole Solar project then ... lesson learnt for us and feedback will be given to the MD re the subcontractors they used... I doubt they will be getting anymore work.

As has been said on the thread - keep them in the house where you can get to them and manage their environment .. simples.

Re temp data (cannot state how accurate ambient temp is as using a UBIBOT sensor) - average ambient temp 14/11 to 29/11 was 12.5C with avg charge rate between 30a and 50a when yielding energy. Since cold snap 30/11 to today - average temp in loft space 7.5c (and at times much lower) with avg charge rate 10a-12.5a.

We have "lost" approx 54kw energy to the grid as the days when we had sun and it was cold the battery only charged at around 600w... rest disappeared .. we didn't have the export payments set up with Octopus as were waiting on install paperwork etc ...

Anyhow, long and sometimes emotional journey but hopefully all resolved in a week or so ... I am now preaching to anyone who will listen - if you get solar ensure the battery and inverter are in the house somewhere!

 

[SeaGal]

Result! (apart from the soil pipe)

 

[GBRDBRY]

Result! (apart from the soil pipe)

 

[coolcarper1]

It's good you got it sorted, unfortunately I don't have a utility room so might have to leave it in the loft but feel a bit robbed not been given any of this information before parting with my cash

 

[GBRDBRY]

It's good you got it sorted, unfortunately I don't have a utility room so might have to leave it in the loft but feel a bit robbed not been given any of this information before parting with my cash

My personal advice would be to def push back hard on the company you paid. They are clearly given instructions NOT to install in Lofts or other cold environments. They have to find a more suitable place - or make one - IMO - The interesting comment from the engineer today was that they must be accessible like all electrical equipment - i.e. you would not put your consumer unit in a loft space or outside on a wall in a plastic box... maybe a gap in Part P regs...
We are removing a couple of kitchen cabinets above the washing machine and dryer and having them on the wall .. its a solid wall so I guess we are lucky ... we did have another option of a cupboard in one of the bedrooms, but this didn't feel "safe" either ...

 

[GBRDBRY]

It's good you got it sorted, unfortunately I don't have a utility room so might have to leave it in the loft but feel a bit robbed not been given any of this information before parting with my cash

did you have a survey before install ? If so - def push back hard as that would be deemed as a failure if they stated ok to install in loft space given fact they are told not to... imo Interestingly - was the install team direct employees or subcontractors ?

 

[coolcarper1]

I have pushed back and awaiting feed back. I had a telephone consultation followed by a servayor who came to the property and nothing was said about the loft not suitable or recommended.
The installers are directly employed by the company I used.

 

[GBRDBRY]

Ok, so you had a physical home survey and they said Loft was good . ?.. there is enough facts and information here to challenge very hard.

I wonder if there is an accreditation scheme, any standards out there ... probably not as its possible it an unregulated "industry" and falls in the gaps of Part P etc etc ...

The electrician who came here didn't even know what the Voltage Optimiser was or what it was for ... "Do you know what this is and do you want it installed ?" I did a google and told him ....

In my case he may be a domestic qualified electrician, but has shown lacking on some of the process and recommended SOP's ... We had two Hive's thrown in as part of the deal, long story - 2 annexes on this property - 3 boilers - he couldn't even get them wired correctly - sorted myself after ... Just seems there is a lack of training or standards ?

The information and standards are there but the info may not be getting passed on ? or worse case ignored in favour of speed, cost etc ....

The roofers who did the panel install were good... but again, lesson learnt as no conversation about options / recommendations to install bird guards .. we have a lot of pigeons... another issue for another day ...