Solis 3k 48es 5g and PylonTech US2000C random automatic forced discharge/re-charge cycle

[Grumbles]

Morning all, has anybody seen this on their set up?

I have 20% discharge limit set with 10% forced discharge. About once a fortnight it wakes up, dumps 10% charge to the grid, then re-imports it plus a bit more. Usually this happens between 6am and 8am, but has occurred as early as 12am. I've analysed the patterns and they are always the same over the same duration (1hr 20 minutes). The 10% discharge appears faster than my average nightly usage so I say 'dumping' rather than 'using'. So, when this happens I'm already down by over 1 kWh.

To put that 10% discharge into perspective, that wold usually last me 3 hours at peak time (6-9pm with microwave, kettle, airfyer and 2hrs TV (48") etc. and lights on).

I've had them since November so I could understand about settling in or testing, but I'm nervous that once I manage to get more than 20% (SOC 40%) on an average day I should be able to carry over to the next day (only happened twice so far....). I don't want to see that being dumbed over the summer! It's a 9.6kW system and I plan to change the parameters to 10%/90% mid-march.

Also, what is the point of a forced charge (discharge). If I have set it at 20%/80% why would it go beyond that - and for that matter, why go below 10% on the forced discharge cycle?

Graham.

 

[rpdom]

Very odd. I haven't seen anything like that on mine and I've got the same inverter and batteries as you, although it sounds like you've got more batteries than my two, if 10% lasts you as long as that.

I assume you haven't set any discharge times.

 

[Grumbles]

Thanks rpdom if it is just me then that's very odd!

I haven't gone near the charge/discharge times yet - but will if:
1) I get paid for for not using energy during the peak window testing.
and/or
2) I can get onto Octopus
And because it's all in the loft and the app doesn't let me do it directly it's an even bigger chore!

I suspected, because it's quite random which day it occurs on (Mondays seems most common) but usually at a fixed time (6am) I assumed it was possibly a Solis engineer or something. I passed the same info onto my installers about 4 weeks ago but no answer yet - and I'm not holding my breath.

I have some other issues but I'm saving those for another thread - but have you noticed the occasional 100% SOC blip as well? I know it's just a random figure and I'm pretty sure it's unrelated but if you have the same system.....(I've had 9 such blips since 1st February 2023)

 

[rpdom]

I don't need to go into the loft very often since I asked Solis to enable Remote Control on the App and Solis cloud website. I can set the charge/discharge details and quite a few other things from my phone or PC.

I haven't seen any 100% blips like that, very odd. It may be a temporary comms fault between the batteries and the inverter causing a bad reading. Do you get any alarms logged?

 

[Grumbles]

Wow - I didn't think this was possible? I thought the only way this was possible was via Raspberry Pi being connected to the machine and a second, better receiver elsewhere.

" I asked Solis to enable Remote Control on the App and Solis cloud website"

As I'm having no luck with my installers I might give that a go - thanks!

As for alarms, nope, the only 2 I have are for on the day of installation. It's not much of an issue but when I actually get around to analyse the data (and there will be a lot) it's going to be a small pain to remove the rogue figures!

One last question, (once again I've raised this with the suppliers and was saving it for another thread), have you ever noticed when your batteries cannot handle the power draw and reverts to a mix of batteries/mains? The app states maximum of 20A. I estimate I'm drawing 8 or 9 max. I assume the batteries cannot handle that when they are a bit cold (although chip temperature of the invertor was still 20C)

This example was 10 minutes after I plugged my car in, using a 7A wall box. That should take 3.5kWh per hour. This example is the most drastic although I have seen similar sometimes when the microwave and kettle are on, for example.

My concern here is, once I manage to get to 100% in the summer I wont be able to get rid of the charge when I want to! On an exceptional day I can generate 20kWh and I want to be able to use as much as possible. (One of the main reason for getting the batteries is to make sure I give as little possible back to the grid at 6p when I have to buy it back at 33p! - I wish we should sell it at market rate like the rest of the industry)

 

[SeaGal]

I have 20% discharge limit set with 10% forced discharge.

Assume you meant forced charge?

About once a fortnight it wakes up, dumps 10% charge to the grid, then re-imports it plus a bit more. Usually this happens between 6am and 8am, but has occurred as early as 12am. I've analysed the patterns and they are always the same over the same duration (1hr 20 minutes). The 10% discharge appears faster than my average nightly usage so I say 'dumping' rather than 'using'.

Do you know that you are exporting to the grid at these odd times? The reason for asking is that the graph shows a reduction in SOC from 20% to about 12%, but there is no corresponding change in the "today energy from battery" line, which remains at 1.5kWh. I'm wondering if it what you are seeing is some anomaly with the reporting of SOC, rather than the inverter attempting a discharge to the grid - which you say hasn't (quite correctly) been set.

Also, what is the point of a forced charge (discharge). If I have set it at 20%/80% why would it go beyond that - and for that matter, why go below 10% on the forced discharge cycle?

The Solis itself is powered by DC so, once the sun goes down it will be powered by battery. Once the discharge limit is reached, the Solis will consume around 30W, so there will be a slow trickle used from the batteries overnight. The Force Charge setting is used to protect the batteries from getting discharged too far in that type of scenario.

One last question, (once again I've raised this with the suppliers and was saving it for another thread), have you ever noticed when your batteries cannot handle the power draw and reverts to a mix of batteries/mains? The app states maximum of 20A. I estimate I'm drawing 8 or 9 max. I assume the batteries cannot handle that when they are a bit cold (although chip temperature of the invertor was still 20C)

The RHI should be able to supply 3000W when battery voltage is 55V. When voltage is less with lower SOC, it will be a bit less. And as you have Pylons which, unusually, are only 15 cells, your voltage will be lower too - so, I'd estimate you should be able to draw somewhere around 2800W from batteries alone. That equates to around 57A on the DC side (@49V) or 12A at 230Vac. Not sure where your figure of 20A comes from - you would need a 4.6kW inverter to achieve that current at 230V.

This example was 10 minutes after I plugged my car in, using a 7A wall box. That should take 3.5kWh per hour. This example is the most drastic although I have seen similar sometimes when the microwave and kettle are on, for example.

Your image did not appear - can you resend? BTW; 7A at 230V is only about 1.6kW, not 3.5kW. And, as an aside, you can just refer to power as kW - you don't need to say kWh per hour ?‍?

 

[rpdom]

Wow - I didn't think this was possible? I thought the only way this was possible was via Raspberry Pi being connected to the machine and a second, better receiver elsewhere.

Hooking up a Raspberry Pi is one of my long-term plans. I'm going to try and put it in parallel with the existing datalogger so I can still have the cloud /app data showing.

I've already got a Pi next to my inverter that logs battery and the loft temperature and humidity for me, so it shouldn't be too much of an issue to add the RS485 connection to it.

" I asked Solis to enable Remote Control on the App and Solis cloud website"

As I'm having no luck with my installers I might give that a go - thanks!

Installers don't seem to tell people about this option. You raise a ticket with the Solis service desk and they usually enable it within 1-2 working days. You do need recent hardware for it to work, but that should be a given on a fairly recent install.
Solis Remote Control Ticket details

 

[Grumbles]

Assume you meant forced charge?


Do you know that you are exporting to the grid at these odd times? The reason for asking is that the graph shows a reduction in SOC from 20% to about 12%, but there is no corresponding change in the "today energy from battery" line, which remains at 1.5kWh. I'm wondering if it what you are seeing is some anomaly with the reporting of SOC, rather than the inverter attempting a discharge to the grid - which you say hasn't (quite correctly) been set.


The Solis itself is powered by DC so, once the sun goes down it will be powered by battery. Once the discharge limit is reached, the Solis will consume around 30W, so there will be a slow trickle used from the batteries overnight. The Force Charge setting is used to protect the batteries from getting discharged too far in that type of scenario.


The RHI should be able to supply 3000W when battery voltage is 55V. When voltage is less with lower SOC, it will be a bit less. And as you have Pylons which, unusually, are only 15 cells, your voltage will be lower too - so, I'd estimate you should be able to draw somewhere around 2800W from batteries alone. That equates to around 57A on the DC side (@49V) or 12A at 230Vac. Not sure where your figure of 20A comes from - you would need a 4.6kW inverter to achieve that current at 230V.


Your image did not appear - can you resend? BTW; 7A at 230V is only about 1.6kW, not 3.5kW. And, as an aside, you can just refer to power as kW - you don't need to say kWh per hour ?‍?

Thanks SeaGal, there's a lot of information here and I can't seem to comment like you have. But here goes:
1) I get about the forced charge/discharge - and the perspective, if it was forced charge limit (from your note (3) I think it is) then it would make perfect sense! - so ,yes, forced charge...

2) I've included the readings from 6am to 8:30am for all relevant fields (i.e. anything not zero). The returned to the grid 'today' never matches the UK 12am clock so it doesn't reset properly - but you're right, there is no change during the period - which would suggest nothing has gone to the grid and that the invertor/batteries have used it? if the system went dormant for 8 hours or so, I wouldn't expect a steady decrease in the batteries but a sudden jump from 20% to 10/11% at 6:15 or so? Also, during the drainage period no data in the sheet seems to show it's going anywhere? The recharge, however, is clearly obvious!

3) The 20A limit is on the app - but also states 100A elsewhere. My car has a 6Kw battery, charges is 2hrs so yes, I think you're right, it's a 16A charger (fitted 7 years ago so I forget!). In your opinion/calculations, does that mean I would expect a maximum output of about 3kW from the batteries, the photo would re-enforce that (I've attached it below). At the time of the photo all that was on was that monitor, a few 15w lights, internet etc. so about 300w max from other sources from experience...

 

[Grumbles]

Hooking up a Raspberry Pi is one of my long-term plans. I'm going to try and put it in parallel with the existing datalogger so I can still have the cloud /app data showing.

I've already got a Pi next to my inverter that logs battery and the loft temperature and humidity for me, so it shouldn't be too much of an issue to add the RS485 connection to it.

Installers don't seem to tell people about this option. You raise a ticket with the Solis service desk and they usually enable it within 1-2 working days. You do need recent hardware for it to work, but that should be a given on a fairly recent install.
Solis Remote Control Ticket details

I bought a real of 6A cable last year for me to replace all co-axial TV ariel sockets with ethernet - didn't think of the loft! now I need more sockets!!!

So, off topic further - how do you power the Pi's in the loft - do you have a 3 pin plug there too? If that's the case, I''ll just get an electrician to do the whole re-wiring if he's going up there anyway!!!!

Thanks for the info on tickets!

 

[SeaGal]

Thanks SeaGal, there's a lot of information here and I can't seem to comment like you have.

just press enter after the bit of the reply you want to split up and it opens the reply up to type back yourself...

But

like

here

this!

I wouldn't expect a steady decrease in the batteries but a sudden jump from 20% to 10/11% at 6:15 or so?

did you mean "would"? I would expect a steady decrease in SOC... mine goes down about 1% every 3 hours (with 14kWh of battery).

But if you look at the spreadsheet, you can see the BMS reporting lower battery voltage (from 46.720 at 06:03 down to 46.420 at 07:43). yes the SOC reported stays at 20% for ages, then drops suddenly - including the strange sudden drop from 15 to 11%.

To me that looks like the BMS on the battery is inaccurately reporting the SOC and then catches up with itself when it realises the battery voltage has dropped.

does that mean I would expect a maximum output of about 3kW from the batteries

yes, with no solar 3000W is the maximum the Solis will deliver

, the photo would re-enforce that (I've attached it below). At the time of the photo all that was on was that monitor, a few 15w lights, internet etc. so about 300w max from other sources from experience...

Why is it exporting more than your usage? Doesn't look right to me, unless I have misunderstood the screenshot.

 

[rpdom]

I bought a real of 6A cable last year for me to replace all co-axial TV ariel sockets with ethernet - didn't think of the loft! now I need more sockets!!!

So, off topic further - how do you power the Pi's in the loft - do you have a 3 pin plug there too? If that's the case, I''ll just get an electrician to do the whole re-wiring if he's going up there anyway!!!!

I thought about running the PI from the AC Backup on the inverter, but I used a Passive PoE splitter ate each end of the cable that I ran up into the loft. I feed 12V from a PSU into one end and have a 12V to 5V converter at the other end. I'm using a PI 3A+, so it doesn't use a lot of power.

 

[Grumbles]

To me that looks like the BMS on the battery is inaccurately reporting the SOC and then catches up with itself when it realises the battery voltage has dropped.

That would explain it perfectly - thanks SeaGal.

Why is it exporting more than your usage? Doesn't look right to me, unless I have misunderstood the screenshot.

Nothing was being exported, the solar batteries were feeding the car at max, the SMART meter also supplying the car (and house). I've only had the SMART meters for 4 weeks and it'll be interesting if it ever shows energy being exported - my batteries reached an all-time high on Monday of 68% so with luck I may have a chance of witnessing it in March! Ditto with the Solis amp, so far, that's also always been zero.