naeemvip3

I'm sorry to hear that. It's scandalous that the inverter lets you do this.
I can confirm that Axpert King 5kW firmware is only for 5kW models; it's not one of the ones that handles two power levels with the same firmware.
So the only way out of your problem is to load 3kW firmware. Alas, though I have nearly a dozen King main firmwares, they are all 5kW.
You will have to get a firmware update from your supplier.
The only alternative would be to replace the control board with a new one, specifically intended for 3kW Kings, pre-loaded with 3kW firmware. That's going to be even harder, I suspect. There are many variations on control boards, and many of the variations are quite subtle. And of course, the firmware loaded onto the processor is invisible.
I wish my news could be better.

Only from the supplier that sold you the inverter. Or from some web page / forum / etc where someone has posted a firmware update file that they obtained from their supplier. It doesn't have to be for your brand, but it has to be for your model. So for example if you have a Mecer SOL-I-AX-3K then you can use the firmware for an MPPSolar PIP-3024MK, for example (because they are the same machine with a different logo on the front). The "Zoo" post may help with identifying what is what.