FoxESS Community - Owners & Installers Forum

phew. glad i put in my install date - i was thinking when i first set up, why does it matter!
im actua;;y happy about the overproduction as long as its not drastic..
i use forecast to set charge limits on battery, so doing slightly more from the sun is ok for me..

AdamNewberry wrote: ↑Sat Mar 07, 2026 12:29 pm phew. glad i put in my install date - i was thinking when i first set up, why does it matter!

It's used to predict how much the panels have degraded, and why production has reduced over time.

However it's just that, a prediction, and tweaking that alone can better match production with forecasts.

AdamNewberry wrote: ↑Sat Mar 07, 2026 12:29 pm i use forecast to set charge limits on battery, so doing slightly more from the sun is ok for me..

I'm not sure if Solcast does better in Australia because they are/were an Australian company, or that forecast.solar doesn't do as well because the site is European based, but forecast.solar can be all over the place some days, since doing lots of parameter tweaking on Solcast settings, it's pretty close most of the time, but the API limit is very limiting.

You can tweak the panel efficiency in the solcast setup, I think it is set at 90% originally which represents a decade of degradation. Try about 96% for a new installation and see how it performs on a clear day. It's hard to compare it on a cloudy day because it's mostly the clouds which determine that day's production.

Looks like degredation defaults are by panel type
I'm pretty sure that for hobbyists accounts, solcast only gives you forecasts in kW, and you then need to turn that 30min guesstimate into a kWh number.

This is what it gives you for hobbyist accounts (this is my west array):
Note you cannot specify the cell technology, only an efficiency factor. Also, it does not seem to take the installation date into account for hobbyist accounts, since if I recall correctly, it was at 90% from the start, and I had to manually set it to 96%.

Regarding the kW to kWh conversion, the Solcast integration on home assistant will do this for you for the overall generation, and the individual array generation.

From what I've seen, in the UK, solcast consistently performs significantly better than forecast.solar.

WyndStryke wrote: ↑Sat Mar 07, 2026 2:05 pm Note you cannot specify the cell technology, only an efficiency factor. Also, it does not seem to take the installation date into account for hobbyist accounts, since if I recall correctly, it was at 90% from the start, and I had to manually set it to 96%.

I had to set our 3kW system to 90% and the 1kW system to 80% to get matching forecasts.

WyndStryke wrote: ↑Sat Mar 07, 2026 2:05 pm Regarding the kW to kWh conversion, the Solcast integration on home assistant will do this for you for the overall generation, and the individual array generation.

Since I'm using it in a python script I just multiply it by 0.5 for kWh, my comment was making it known that's what you get, that's all.

WyndStryke wrote: ↑Sat Mar 07, 2026 2:05 pm From what I've seen, in the UK, solcast consistently performs significantly better than forecast.solar.

Just have to tweak the settings properly before that will happen.

The Solcast forecast for today suggested that we might get ~20.0kWh for both systems and we've had 19.1kWh with the panels still doing a couple of light bulbs worth of power.

forecast.solar this morning said we'd get ~8kWh, although the forecast did improve as the day went on in subsequent forecasts.

AdamNewberry wrote: ↑Tue Jan 13, 2026 8:32 pm also gents,
fox updated my evo firmware last night - i can now write MaxSOC on grid via the inverter.
the only constraint is that mode scheduler must be disabled (have queried if there is a way for me to toggle that via modbus).
But for me - i was only using mode scheduler for forced charge overnight - now i can set the max SOC on grid, I can default to the older Force Charge periods. Happy days.

Managed to get a full control loop going now!
Checks solar forecast tomorrow - works out a reasonable Max SOC at 7pm and writes it to the register.
Force charge happens in the last 100minutes of the IOGo cheap rate overnight.
To handle IOGo intelligent dispatching, HA checks the dispatch windows, and if car is plugged in - if plugged in, moves zappi from eco+ to fast to enable charge. Limits the battery discharge current to a value that roughly allows only the house load to discharge - to avoid battery drain into the EV.

and created a nice dashboard for that too!

Hi Adam,

I’m currently trying to set up a similar automation, but I haven’t been able to find the entity you mentioned, “MaxSOC on grid.” Should this perhaps be number.min_soc_on_grid instead?

Also, has anyone found a way to force the battery to discharge? I have an export limitation and would like to discharge the battery before recharging it with solar energy, to help minimise clipping.

Another idea I’ve been considering is a method to export all solar energy when my panels are generating below the export limit, and only charge the batteries when generation exceeds the export limit.

I’ve already written automations to divert excess power to charge my car and switch on the immersion heater, but once these no longer require power, the excess energy ends up being clipped.

If anyone has any suggestions or ideas, I’d really appreciate hearing them.

Thanks,
Brian

Hi Brian. It’s not an entity. It’s via the actions tab in HA. You want to write to register 41010.

Hi Adam,

Thanks for getting back to me so quickly.

Can you share the modbus document you received from Fox. The document vinayrk posted on this thread doesn’t have the register you mentioned.

Thanks

Brian

Sure, Brian, apologies I missed this message.
Also i just got notice that the pull request was merged to the main branch on the modbus integration on github.
if anyone wants to give it a try!

Cheers
Adam

Hi all,

I'm getting my installation this time next week and I've been reading this thread with interest.

What id like to know is if there is an way currently to access the full read/write modbus integration via either an ethernet cable or via WiFi, instead of having to resort to a elfin or similar?

I've read elsewhere that Fox disabled accessing modbus via ethernet for example, so just trying to ascertain the correct approach.

Thanks

Hello

Reading from my EVO 10-5-H works fine over WiFi. The difficulty seems to be getting an accurate list of which register is which. The 20251215.V1.05.04.00 pdf seems to be the closest I've found so far. I tried writing to a couple of registers but they just seem to time out. I've found an API that should do what I'm looking for so hopefully that works...

elljay wrote: ↑Thu Apr 02, 2026 4:05 pm Hello

Reading from my EVO 10-5-H works fine over WiFi. The difficulty seems to be getting an accurate list of which register is which. The 20251215.V1.05.04.00 pdf seems to be the closest I've found so far. I tried writing to a couple of registers but they just seem to time out. I've found an API that should do what I'm looking for so hopefully that works...

That sounds great. I'll download the document and have a look at it. What API have you found?
Thanks

I've found a few bits of info:

The Fox ESS official API is here

The Fox Installer site with Firmware Release notes is here, though they've only been updating them since January..!

Can't remember where I downloaded the Fox Modbus 20251215 definition from, but have attached it to this post...

That's great thank you. I've asked my installers to install the modbus for me looking forward to getting it all set up etc if I can wrap my head around it

I've got the elfin device, used the settings guide, all matches. Wired upto pins 11&12 on the coms port of my Evo.

I can ping the elfin on my network and get a response, but still get a timeout error.

Any advice welcome

The error:

Error connecting to your adapter or inverter. Ensure the adapter is properly configured and is correctly wired to your inverter (see the setup link above), then try again. Details: Modbus Error: [Input/Output] Modbus Error: [Connection] CustomModbusTcpClient 192.168.1.136:502; Connection to (192.168.1.136, 502) failed: timed out; Connection to (192.168.1.136, 502) failed: timed out; Connection to (192.168.1.136, 502) failed: timed out; Connection to (192.168.1.136, 502) failed: timed out; Connection to (192.168.1.136, 502) failed: timed out; Connection to (192.168.1.136, 502) failed: timed out; Connection to (192.168.1.136, 502) failed: timed out

Edit: I figured it out , it's because I had DHCP enabled.

I now have an invalid register error where all items are unknown.

I've looked at the page on the original modbus for a fix but there's no beta version for the Evo fork.

MartyS,

Have you followed these instructions to set up the Elfin?

https://github.com/nathanmarlor/foxess_ ... Elfin-EW11

Brian

BOD wrote: ↑Fri Apr 10, 2026 4:00 pm MartyS,

Have you followed these instructions to set up the Elfin?

https://github.com/nathanmarlor/foxess_ ... Elfin-EW11

Brian

I have indeed. All matches what the pages advises.

I'm assuming I'm correct in putting the wires in 485a and 485b and not the meter 485 inputs.

My pull request for my evo support feature has been merged to main branch but not yet released by the maintainer.

AdamNewberry wrote: ↑Fri Apr 10, 2026 5:10 pm My pull request for my evo support feature has been merged to main branch but not yet released by the maintainer.

Ok thanks Adam. Shouldn't my Evo work with your version in the meantime?

It should do as others have gotten it to work.
Not sure you use Claude or ChatGPT but I find putting error logs there more or less gets me to the solution eventually

MattyS wrote: ↑Fri Apr 10, 2026 4:59 pm

BOD wrote: ↑Fri Apr 10, 2026 4:00 pm MartyS,

Have you followed these instructions to set up the Elfin?

https://github.com/nathanmarlor/foxess_ ... Elfin-EW11

Brian

I have indeed. All matches what the pages advises.

I'm assuming I'm correct in putting the wires in 485a and 485b and not the meter 485 inputs.

Those are the correct inputs. I had an issue where my installer told me he had used a different pair of wires to the ones he had actually used. Check the pins are wired to the wires you are using. Also check the wires are the correct way round.

Another thing to check is the port on the inverter display is set to 502.

Brian

I seem to be just making it worse

Some of the registers throwing errors are ones I assume should be working regardless.

Interestingly, the integration seems to think I have a 10kWh inverter. I have a 5kWh. Maybe that's a clue