A little grid impord during No Discharge state

[zlakes01]

As the title say Solax modbus allow a smal grid import (approx 350 W) when the inverter is in "No Discharge" mode.

[TCWORLD]

Grid import is the expected behaviour if there is insufficient solar to cover the house load in this mode.

Could you provide more information - what operations are you performing? Remote control Mode 1 or Mode 8? Graphs of solar/house load/grid would help. As would enabling debug logging for a while while the mode is running.

[zlakes01]

I use Mode8. In the picture is typical grid support when PV is sufficient. The log is attached.

home-assistant_solax_modbus_2026-07-19T08-06-46.730Z.log

[TCWORLD]

Looking at the logs, I think what you are seeing are losses that are not being accounted for as its hard to know what exactly these loses are going to be.

Essentially in excess conditions, the control loop calculates "solar - house load", the result is the amount forced into the battery to charge.

However the reported solar power is actually higher than reality as it doesn't include any of the losses through the MPPTs into the DC bus. The inverter also has losses that aren't known so the house load calculation is not always accurate. The net result is there will be some discrepancies which are not accounted for, particularly at high powers.

That 370W on a 10661W of solar is only 3% which is well within the realm of expected losses so it's not entirely surprising.

In the past in some of the control modes we've included measured grid power to augment the calculations, however that leads to some very undesirable behaviour for conditions with rapidly changing loads and solar.

I'll have a think on it, but at the moment with the limitations we have (slow update rate, generalised logic not accounting for inverter specifics) the currently exhibited behaviour does not seem terrible.

[zlakes01]

This phenomenon is not present in disabled state. Otherwise it would be lost as explained.

[TCWORLD]

The losses are there when disabled. The difference is that the inverters own internal control loop has faster access to the data than we do, and is fully tuned to the specific hardware to account for it.

If you create a sensor that sums inverter power and total battery power, and subtracts the result from PV total power, you'll find the result is non-zero regardless of what mode is being used.

This is mine for example (I named my sensor Self Power, though it's basically losses):