I have an issue and i'm not sure whether it is related to inverters or batteries

Good morning!

It sounds like an inverter setting. I have a Generac PWRCell solar rig including 18kW of battery storage. My system is also tied to the grid. There are four usable settings on my inverter:

• Grid Tie - Direct export of excess power back to the grid (not to be used of you have batteries)
• Self Supply - Uses the batteries until depleted to the low battery threshold, then swaps to GRID. As the solar panels come back online, they begin to take over when generating more than the house is using; prioritizing home, then battery recharge. Once the batteries are near capacity in this setting (above 95%), the inverter begins to shunt power back to the grid. When the mornings are sunny and clear, I can fully recharge my batteries by 10AM.
• Clean Backup - The house is powered off the grid until the solar panels come online and begin generating power. All of the solar generation goes to charging any trickle depletion on the batteries; load sharing does not happen until the batteries are back to near full capacity (>98%). Over the winter, I kept the inverter in this setting.
• Priority Backup - Uses the grid and solar to fully charge the depleted batteries. I used this once when my batteries were completely depleted and we had bad storm front rapidly approaching the region.

When I am in Self Supply mode (getting there; I live in RI and the days are just starting to get long enough to make it work), I keep my battery low power threshold set to 30%. The batteries will sustain the house until that threshold is hit, then swaps over to the grid. That 30% is also my emergency reserve is something happens and I need some power in the house. It sounds like your system is in some form of "Clean Backup" mode until the batteries reach capacity charge.

One other thing you might look into is a scheduling function in your inverter. If it is active, you may have a ToU setting (Time of Use) that is preventing the inverter from swapping from one mode to another during a period of time.

You also mention you have two inverters. I wonder if there is some mis-match between the settings on either box?

What inverter do you have? Each brand inverter is different.

Mine is an Outback Radian and inline the Gentac can be used with a battery. Actually, the Outback must be used by a battery.

These are custom-built Chinese inverters. They're nothing like Outback or other reputable brands.