Drawing from grid when batteries 80% charged

[ringding]

Hi all,

We've had our system installed for over 2yrs and have been very pleased with it. However, for the first time, I've seen a behaviour that I don't understand, and seems wrong.
Today the batteries are pretty much 80% charged, and yet the system is drawing from the grid to meet the load. It's supplementing this with a small amount of power from the panels. System is set to "self use".

We've recently switched to Octopus Flux, so don't really want it drawing from the grid unnecessarily in the expensive period betwee 4 and 7. Is there a way to force it to use the battery?

[ringding]

I should add that I've 'confirmed' the draw by looking at the in house smart meter panel, which shows approimately the same load. So I think the ESS panel is showing something representative of what's really happening.

[ringding]

Very odd. After an hour of unecessarily drawing from the grid it's now returned to normal.

Don't like things I don't understand (which is a lot!), but I'll live with it. At least it led me to discover there's a forum for Fox ESS!

[Dave Foster]

It's unusual for it to do that, forgive me for going through the more obvious things first that could cause it (I will discount temperature as it is mild at the moment) -

If you have a charge period set (even if the charge from grid is disabled) it will stop the battery from discharging - your charge periods should always be set to 00:00 if not in use.

What are your minsoc settings (they should both be set to 10-20%)

Do you use schedules (Force Charge / Discharge) - if so were any left enabled ?.

Lastly, is your battery firmware up to date - if the batteries are in a state if imbalance it is possible the BMS paused their operation - if you can let me know what batteries and version (i.e. HV2600 V1) I can check latest firmware for you. You can check the battery firmware at the Inverter's panel by clicking on About, Bat Ver (it will show M:xxxxxx and S:xxxxxxx for each slave), also the latest Foxess app shows battery versions if you click View whilst on the battery screen.

[ringding]

I think you've hit the nail on the head! I had a 'charge from grid' set the day before yesterday, to top up before the expensive part of our tariff. I turned it off afterwards, but the times are still in the entry fields. Looking at the inverter details it did the same today, drawing from grid when the battery had charge, so I think you must be right.

Thank you for the heads up, as that's something I wasn't aware of.

[Rolandgreen]

I am a new PV+battery user, (Feb 2023) I wondered at the -ve battery figure,then realised I was charging the batteries from the grid. I disabled this, but they still charged from the grid, so I changed the "time period" to just a few minutes....ignored by the system. Any ideas on this?

[reef]

Did you set the time period on the cloud site or in the app? I've never had the time windows stick using the app and always used the site.

[AnnetteBishop]

Just had solar installed, 25/03.
In self use mode the batteries always charge from grid, so we are pulling large loads once PV, stops (at night).

If I use max feed in to grid battery drifts down to 20% min SoC, , switch to self use and the system grabs a full charge from the grid.

Just reading there's a max state of charge that could be set, this sets max draw from grid, lets say 30% and forces system to pick up rest from Solar, but I have no idea where this setting is.

Firmware version 1.6.

Any clues?

[Dave Foster]

Just had solar installed, 25/03.
In self use mode the batteries always charge from grid, so we are pulling large loads once PV, stops (at night).

If I use max feed in to grid battery drifts down to 20% min SoC, , switch to self use and the system grabs a full charge from the grid.

Just reading there's a max state of charge that could be set, this sets max draw from grid, lets say 30% and forces system to pick up rest from Solar, but I have no idea where this setting is.

Firmware version 1.6.

Any clues?

Which inverter and batteries do you have ?.

In self use mode if there is sufficient solar it should cover the house load and then charge the batteries - it should never charge from the grid unless you have a charge period set to do that - do you have any charge periods set ?.

Could you post a picture of your real time energy flow from the app (or the website) - it sounds as if your CT clamp has been put in facing the wrong way at installation.

[AnnetteBishop]

I worked out how to set the Max SoC, but its made no difference.
Numerous chats with Fox help desk and installer visit the problem seems to be that we have an issue with the CT clamp on the incoming mains, its not wired in but has a transmitter, not using the Internet. (Not fully up on the tech here). We have a 3 storey town house with a lot of steel in the building. Dropping a wired connection will be tricky. Can we get a WiFi enabled CT clamp that communicates with the inverter then the system can use our home network?? Saves a lot of holes in walls.

[Dave Foster]

I’m not aware of any wifi based CT clamps - there are more complicated solutions that require an RS485 meter to be fitted (replaces the a CT clamp), there is then a LORA device that will transmit the signal to another LORA device fitted at the inverter (up to 3,500 metres in open air).

This is a known good device https://www.pusr.com/products/serial-r ... 206-p.html but by the time you’ve bought a pair of these and fitted an RS485 meter in all honesty it would likely be cheaper and certainly more reliable to run a cable between them.

[AnnetteBishop]

The electrican is visiting on Tuesday. He originally fitted some sort of wireless device, not tech enough to fully understand, but he gets the issues. Running cables is not so easy but might be the best option as you say.

Thanks for the information.

[AnnetteBishop]

Ureka! Its all working as it should. The inverter did not know what the mains feed was doing. My fears of my house looking like a Swiss cheese were unfounded, just a tiny bit of white trunking, near skirting, in a cupboard- result.

Electrican used installed cat5 cable (its in every room),
Definitely worth considering for anyone else with similar issues.