With that regard, Can I combine the inverter output circuit of let's say (4)grid-tied inverter and the AC output of (1)hybrid inverter and connect it as supply/line side tap? By the way we are using Solax SK-TL5000E hybrid inverter with Emergency Power Supply(EPS) function. Thanks for your input!
When you connect the output of a grid-tied inverter (or 4 of them) to the output of a hybrid inverter (a.k.a. grid-tied battery inverter), this is known as AC coupling. It is important to understand that you can over-charge the battery with this type of system if you don't include design features to prevent it. Specifically, in the event that the grid is down, the sun is shining, and the backup loads are small, the grid-tied inverter(s) will send an unregulated charge back through the hybrid inverter and over-charge the battery bank. Design features to prevent this scenario from occurring should be inherently fail safe. For instance, a voltage sensing relay, using the upper limit of battery voltage as the set point, can be used to drive the coil of a power relay that opens the grid-tie inverter output circuit. If the "normally open" contacts of both relays are used, the system will shut down the grid-tie inverters in the event of a component failure. Or better yet, use SMA inverters that take care of this problem for you automatically.
If you do use relays to prevent over-charging, you will want to set the disconnect voltage at the upper limit of the battery voltage, and the re-connect voltage low enough to prevent the system from cycling on and off continually.
You mentioned connecting the hybrid inverter as a supply side tap. This is confusing. I assume that your hybrid inverter has an AC input that connects to the grid, and an AC output that connects to a backup loads panel. If you connect the grid-tied inverter(s) to the AC output of the hybrid inverter, you cannot also connect them as a supply side tap. You can connect the AC input of the hybrid inverter as a supply side tap, but not the AC output. You need to make sure that your hybrid inverter has the capacity to pass all of the grid-tied inverter current through from its output terminals to its input terminals.