Solax 5.8kw battery depth of discharg

[Pjvo]

Hello everyone,

I have a 6.3kw solar panel system with solax X1 Hybrid G4 V2 inverter, and a solax triple power T-BAT H 5.8 battery.

The system is configured to self consuption, so at night the battery provides energy to the house, and when it reaches the value of maximum depth of discharge I get the energy from the public grid.

Everything seems to be working fine, except that my battery frequently discharged to 5-7% (18 times in 2 months) when solax refers it is 10%, after talking to the installing company they said that their provider had upgraded my battery fimrware.
It never went back to 5%, but still goes to 8 or 9%, I have complained to them, the said that the changed the depth of discharge to 85%, but still in the morning the battery gets to 11% (wich is above the 10% that solax mentions on their site).

Talked to them again, they said that it is because of the battery self consuption.

But if the inverter is configured to 15% shouldn't it stop the battery discharge at that point, and not let it get down to 11% or 8%.

I am only trying to understand if this is normal, I don't want to reduce my battery life cycle due to get bellow the 10% that solax recommends.

Is the battery self consuption a valid argument?

Thank you for any help you can give me.

 

[SeaGal]

Maybe the Solax works the same as my Solis; when the inverter stops using the battery at whatever SOC you have set, the Solis will still use the battery to power itself - approx 30W in the case of the Solis. So it is normal for the SOC to drop below the value specified, especially if the battery is used up early in the night.

 

[Pjvo]

SeaGal, that is one possibility, I will try to find if solax inverters work that way.

 

[SeaGal]

Further thought. The Solis has a minimum discharge SOC setting (i.e. at which the inverter stops using the battery). But, it also has a 'force charge' SOC setting which is typically set lower than the min discharge setting and will trigger the inverter to charge the battery up a few % of SOC from the grid - this is used to stop the battery getting too low. So those values may be something like 15% min discharge value to stop using the battery for house load and 10% force charge setting to stop the battery getting too low. Maybe the Solax has something similar too?

 

[Pjvo]

Thank you, that was spot on, I went to the solax manual and there it was:

d) Self-use mode
In this mode, you can set the power reserve percentage of the minimum
battery state, set whether the power can be taken from the mains side to
charge the battery, and set the amount of power to charge the battery.
For example: set the reserved minimum SOC of the battery capacity to
"10%", which means that when the battery has been discharged to 10% of
the battery capacity, the battery is not allowed to continue to discharge;
When Charge from grid is set to "Enable", the utility power is allowed to
charge the battery; when set to “Disable”, the utility power is not allowed to
charge the battery;
Charge battery to is set to 90%, indicating that the mains is allowed to
charge the battery at 90%.

So now I can change the status of "charge from grid" from disable to enable and set a percentage to charge from grid, keeping the battery always above 10%.

SeaGal, once again thank you.