FoxESS Community - Owners & Installers Forum

Hi all question.

Have 10.8kw qcell panels installed 2022 with fronius 8kw single ph inverter.

2026 added foxess 42kw eq4800 with kh9.9 single ph inverter. Fronius inverter removed

26 panels east/west orientation on 2 strings.

With the old smaller inverter same time last year i was getting 7.2kw solar production now only 6.5kw with newer larger inverter.

firmware master 1.6 slave 1.02 manager 1.58. read about a 3.3kw cap per string on fox inverter that should have been fixed with firmware update to 5kw.

Anyone else have this problem? Export cap is at 5kw but when I forcecharge battery at 10.9kw solar production stays at 6.5kw.

Any advice/settings changes would be appreciated

There was a firmware release that increased the string limit to 5kW per string (although because of lack of release notes we don't know precisely when), not sure whether this is affecting you here but the latest firmware is Master 1.71, Manager 1.67, Slave 1.03 so you are quite a bit behind the current state.

I'd recommend updating and re-testing over a couple of days, as ambient temps being hotter could easily make that amount of difference through panel derating.

Make sure you get all 3 firmware updates, including 'Slave' as it is very likely the hard string limit is coded there.

Yea I seen on the forum there are firmware updates but I can’t update anything in the app if I go to the devices

niek604 wrote: ↑Mon Aug 10, 2026 9:11 am Yea I seen on the forum there are firmware updates but I can’t update anything in the app if I go to the devices

Fox sometime suspend the update feature, and have recently - best way to do it is to raise a service request through the app click 'Me', 'Submit a ticket', or you can get their local email address from the 'Contact Us'.

In the request make sure you specify your inverter SN, and the string limit problem you are seeing and ask for Master, Manager & Slave to be updated.