During force charge, why is the KH10 inverter limited to 10kW from AC and 1kW from PV (max 11kW total)?
According to the EQ4800 specifications, the nominal operating voltage is 403.2V, and the recommended charging current is 30A (max 50A). A simple P=VA calculation means the recomended charging power is 12.1kW (max 20.2kW).
During force charge, why is the KH10 inverter limited to 10kW from AC and 1kW from PV (max 11kW total)?
During force charge, why is the KH10 inverter limited to 10kW from AC and 1kW from PV (max 11kW total)?
Because it is a KH10 with a maximum AC power of 10kw, a KH7 would be 7kW, the limit is set by the inverters power limit or the (BMS maximum charge current * battery volts) whichever is the smallest.
The AC output is used to provide power to the house load when discharging from the battery. AC output is not used to charge the battery.
The inverter is connected to the battery by DC not AC. The Datasheet for the inverter specifically contains the DC specifications of the battery for charging and discharging.
As previously provided, the EQ4800-L9 operates at a voltage of 400V and the inverter has a maximum charge current of 50A (battery recommended is 30A). This shows the KH10 is capable of charging the battery at 20kW (battery recommended 12kW).
The AC Input specifications are what determines how much power can be used to charge the battery (allowing for AC to DC efficiency which is 97%).
As shown, for Australia, the max AC Input power is 14.5kW.
The inverter is connected to the battery by DC not AC. The Datasheet for the inverter specifically contains the DC specifications of the battery for charging and discharging.
The AC Input specifications are what determines how much power can be used to charge the battery (allowing for AC to DC efficiency which is 97%).
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Apologies, I guess I'm making some incorrect assumptions (that make sense to me) based on the data available to me in the datasheets. I'd very much like to understand how the inverter works (I was promised I'd be able to fully charge the battery during the free 3 hour period). Is there any more detailed reference material available for the inverter? The AC Input power specs are higher than the AC Output. Besides charging the battery, what else is the AC Input used for?
Also why can't the combined available PV + AC be used to maximise the battery charging. If it can only use 10kW from AC, when the PV is producing 2kW or more, why can't the inverter charge the battrey at above 11kW? Where does the 11kW limit come from?
Also why can't the combined available PV + AC be used to maximise the battery charging. If it can only use 10kW from AC, when the PV is producing 2kW or more, why can't the inverter charge the battrey at above 11kW? Where does the 11kW limit come from?
Unlike the traditional modular inverter with distinct MPPT and charger, the hybrid inverter has the added challenge with the charge controller being both DC and AC coupled so it can charge from either source or blend the two sources to get maximum charging whilst still meeting the anti-islanding protection requirement; I suspect this is what sets the charge controllers power to the inverter AC maximum power limit.
The inverter internally can handle more power on the vbus than its AC limit, up to the maximum power limits for the combined strings. Where the MPPT's are generating more power than the rated AC output, surplus power will be diverted to charge the batteries. Equally when charging batteries from PV, if there is more DC power being generated than the batteries charge controller can handle, the inverter will export the surplus up to the maximum AC power limit. If the MPPT's don't have a consumer for all the power they are generating they will derate.
In practice what that means is that your battery maximum charge power will be limited to the AC rating of the inverter, which for most batteries isn't a problem as the BMS sets the maximum charge current and that will be the limiting power factor, however with the higher voltage stacks such as EQxxxx and EPxx it is possible the inverter rating could be lower.
Also worth noting the BMS (BMU) is constantly managing the charge current and will ramp up or down depending on temperature, and soc.
A colleague of mine has done a high level schematic block diagram which helpfully details the system losses in the various stages and indicates where a Fox sensor is measuring it’s feed. https://github.com/TonyM1958/HA-FoxESS ... it-work%3F
Sadly Fox haven't shared the direct schematics for their hybrid but over the years a few people have opened them up and reverse engineered them, and they are very similar to the reference diagrams you can find on the internet for other hybrid inverters (Solax).
The inverter internally can handle more power on the vbus than its AC limit, up to the maximum power limits for the combined strings. Where the MPPT's are generating more power than the rated AC output, surplus power will be diverted to charge the batteries. Equally when charging batteries from PV, if there is more DC power being generated than the batteries charge controller can handle, the inverter will export the surplus up to the maximum AC power limit. If the MPPT's don't have a consumer for all the power they are generating they will derate.
In practice what that means is that your battery maximum charge power will be limited to the AC rating of the inverter, which for most batteries isn't a problem as the BMS sets the maximum charge current and that will be the limiting power factor, however with the higher voltage stacks such as EQxxxx and EPxx it is possible the inverter rating could be lower.
Also worth noting the BMS (BMU) is constantly managing the charge current and will ramp up or down depending on temperature, and soc.
A colleague of mine has done a high level schematic block diagram which helpfully details the system losses in the various stages and indicates where a Fox sensor is measuring it’s feed. https://github.com/TonyM1958/HA-FoxESS ... it-work%3F
Sadly Fox haven't shared the direct schematics for their hybrid but over the years a few people have opened them up and reverse engineered them, and they are very similar to the reference diagrams you can find on the internet for other hybrid inverters (Solax).
If the KH10 has a 10kW limit for AC charging the battery, what is the limiting factor for the total charge to the battery (PV + AC) being 11kW?
When PV is above 1kW during force charge, the AC Input power is only 11kW - PV. Here is an example.
When PV is above 1kW during force charge, the AC Input power is only 11kW - PV. Here is an example.
Not sure, do you have home assistant installed? - it would be really useful to see the traces of your BMS max charge power sensor, actual battery charge power, battery voltage and the PV traces (i’m assuming they were being clipped?).
Given the system losses it’s likely the actual charge power going into the battery was 400-500 watts less the 11kW which is getting close to the 10500VA apparent power limit.
Given the system losses it’s likely the actual charge power going into the battery was 400-500 watts less the 11kW which is getting close to the 10500VA apparent power limit.
No I do not have HA installed. How do I get those traces?
The max battery charge current on the inverter is set to 50A. Is this setting on the AC side (240V) or the DC side (400V)? If on the DC side, then the max charge power would be 20kW (10kW AC + 10kW DC ?).
The support person I spoke to said it is a maximum of 11kW becasue it is charging the battery at 220V. Is there another setting only available to installers that sets either the charge voltage or max charge power? I would think (assumption) that the max charge current setting of 50A is on the DC side and the installers have incorrectly set either the voltage to 220V or max power to 11kW (thinking it is charging at 220V).
I currently have 4kW of PV and thinking of adding more so I can fully charge my battery each day. However, if I can't get the full benefits of the 4kW I have now there's no point adding more.
The max battery charge current on the inverter is set to 50A. Is this setting on the AC side (240V) or the DC side (400V)? If on the DC side, then the max charge power would be 20kW (10kW AC + 10kW DC ?).
The support person I spoke to said it is a maximum of 11kW becasue it is charging the battery at 220V. Is there another setting only available to installers that sets either the charge voltage or max charge power? I would think (assumption) that the max charge current setting of 50A is on the DC side and the installers have incorrectly set either the voltage to 220V or max power to 11kW (thinking it is charging at 220V).
I currently have 4kW of PV and thinking of adding more so I can fully charge my battery each day. However, if I can't get the full benefits of the 4kW I have now there's no point adding more.
Other than battery voltage trace which you can see on the web version, without HA you cannot see the BMS current limits.brunofabre wrote: ↑Thu Jan 01, 2026 10:23 pm No I do not have HA installed. How do I get those traces?
Correct, the max battery charge current in the inverter defaults to 50 for the KH and that is that maximum allowable DC charge current to the batteries, but the BMS maintains it's own Max DC charge current which changes depending on temperature and SoC - this image is based on a slightly older BMU specification but shows it effectively. (it is managed by the BMS and cannot be set)brunofabre wrote: ↑Thu Jan 01, 2026 10:23 pm The max battery charge current on the inverter is set to 50A. Is this setting on the AC side (240V) or the DC side (400V)? If on the DC side, then the max charge power would be 20kW (10kW AC + 10kW DC ?).
The support person I spoke to said it is a maximum of 11kW becasue it is charging the battery at 220V. Is there another setting only available to installers that sets either the charge voltage or max charge power? I would think (assumption) that the max charge current setting of 50A is on the DC side and the installers have incorrectly set either the voltage to 220V or max power to 11kW (thinking it is charging at 220V).
There are max AC limits in the settings which are used where the grid has a limited supply, I don't think they are responsible but you can check them in Settings, on-grid, Export Control, ImportLimitCur (normally set to 100A AC or your supply fuse limit), and some inverters have ImportLimitPwr (normally set to 30,000 unless you have a restricted supply).
That's a hard one to answer for me, in the UK / Europe where the PV is mostly used to charge the batteries through the day (and run the house through the night) with any surplus exported at a export tariff (so more PV generation is always a good thing) - it appears you have differing requirements in Aus using the batteries to load shift.brunofabre wrote: ↑Thu Jan 01, 2026 10:23 pm I currently have 4kW of PV and thinking of adding more so I can fully charge my battery each day. However, if I can't get the full benefits of the 4kW I have now there's no point adding more.
Based on the BMS battery charge current grid you provided, I would be operating in the range of 50A 21<T<44 and 10%<SoC<90%.
My ImportLimitPwr is set to 15100W and the ImportLimitCur set to 63A (Grid voltage is 240V).
We have established that the max AC Input power for the KH10 is 10kW (240V @ 41.67A). What I really want to know is what is limiting the total charge power to the batteries to 11kW? When my PV is above 1kW, it will reduce the AC Input power so that AC Input power + PV power = 11kW (as shown by the app screenshot).
What is happening:
PV=2.72kW
Load=0.81kW
Grid=9.09kW (0.81kW to Load, 8.28kW to Inverter)
Battery Charge=11kW (2.72 from PV + 8.28kW from AC Input)
What I expect to happen:
PV=2.72kW
Load=0.81kW
Grid=10.81kW (0.81kW to Load, 10.0kW to Inverter)
Battery Charge=12.72kW (2.72kW from PV + 10kW from AC Input)
There seems to be something that is restricting the total (PV + AC) battery charge current to 11kW. I want to know if this is a configuration setting that has been incorectly set.
When I eventually got through to phone support (in Australia), they said the limit was due to the 220V AC voltage for 50A max charging current to the battery. The 50A max charging current to the battery should be at the battery DC voltage not the AC voltage. I suspect the 11kW limit has been set due to the misunderstanding of the DC vs AC voltages.
My ImportLimitPwr is set to 15100W and the ImportLimitCur set to 63A (Grid voltage is 240V).
We have established that the max AC Input power for the KH10 is 10kW (240V @ 41.67A). What I really want to know is what is limiting the total charge power to the batteries to 11kW? When my PV is above 1kW, it will reduce the AC Input power so that AC Input power + PV power = 11kW (as shown by the app screenshot).
What is happening:
PV=2.72kW
Load=0.81kW
Grid=9.09kW (0.81kW to Load, 8.28kW to Inverter)
Battery Charge=11kW (2.72 from PV + 8.28kW from AC Input)
What I expect to happen:
PV=2.72kW
Load=0.81kW
Grid=10.81kW (0.81kW to Load, 10.0kW to Inverter)
Battery Charge=12.72kW (2.72kW from PV + 10kW from AC Input)
There seems to be something that is restricting the total (PV + AC) battery charge current to 11kW. I want to know if this is a configuration setting that has been incorectly set.
When I eventually got through to phone support (in Australia), they said the limit was due to the 220V AC voltage for 50A max charging current to the battery. The 50A max charging current to the battery should be at the battery DC voltage not the AC voltage. I suspect the 11kW limit has been set due to the misunderstanding of the DC vs AC voltages.