I built high frequency inverter but i did the ful calculations and test I get 3.5 kW from 5kw so what I did is add one more transformer and the inductance increase and I was able the get the full 5 watt continuously and the voltage didn't drop but in the bigger industry they won't do that because it causing more money to build it to work the same as low frequency inverter its possible to build high frequency inverter to work the same as low frequency inverter it just requires more parts and cost goes up

It will be more fair to compare with the good brand of high frequency inverter like Sunsynk, Deye, etc. And even you locally manufactured high frequency inverter, it still cannot working under bad voltage scenario. The limitation of high frequency inverter doesn't due to the "Import".