Under such circumstance (SOL mode), under WAPDA once output current of the inverter becomes equal to the input current, you need to cross verify that as how much energy your solar panels is producing and how much from solar panels is going back into charging the battery bank. Most likely, power produced from Solar panels is not sufficient at this moment and 100% of it is going back into charging Batteries. That’s why Inverter has gone into by pass mode and transferring the entire input into your output.
Honestly, if you will look at the manual, since inverter is made in Taiwan, Manufacturer has messed up in
explaining SOL and SBU in manual. Refer to Page 15, you may have to signup
https://voltronicpower.com/content/download/Manual/AxpertVMII-PF1_manual.pdf
Now if you will trust me, I will dictate you the settings on your inverter try it for few days and let me know the results. then later, i will tell you about few tweaks to suit your own requirement. Least you would know as what you want and can command your inverter to do so.
Select Following
01: Select SBU
02: Maximum Charging Current,
Select 20 A ( AMP Rating of Batteries/10) =20 MAx, so you cant exceed this, lower it is, better you are, i would have selected 15, if it allowed me to set 15.)
03: AC input range :UPS
05: User Defined: USE
09: 50HZ
10: 230 Volts
11: Maximum Utility Charging
Current: 10A
12: Setting Voltage Back to
Utility Source: 23Volts
13: Setting Voltage Back to
Battery Mode: 28.8Volts
16: Charge Source Priority: Solar
+ Utility OR CSO (Solar First) depends on you. as both are ok
22: ON
23: BYE
26: Bulk Charging Voltage: 28.8 Volts
27: Floating Charging Voltage: 27Volts
29: Low DC cutoff Voltage:
21Volts, Lower to 20.5 if it has an option to select
let me know if you have any questions for these settings, these are for lead acid batteries and 24Volt system
P.S: your few setting were wrong like
11: Utility Charging current: Should be 10 as otherwise you are commanding inverter not to charge the batteries from solar. as in 02: maximum charging current= Solar + Utility= 20 so if utility in no: 11 is 20 then it wont take anything from solar once utility is available.
12: if you dont want to drain the batteries then you can keep it to 24Volts
13: Voltage back to battery mode: 28.8Volts
16: is ok
run things in SBU, i have selected user defined settings on battery because i am more comfortable in dictating the batteries as what i want rather then embeded variable in flooded type which i cannot see. Dont use equalization setting because it requires adjustment of few more variables down the line which i have never tried so wont comment. turning it on blindly will kill your batteries.