Optocouplers are widely used in power electronics to isolate the power stage with the control area. Every optocoupler has a limit of operating frequency. Recently, while working with my hardware setup i noticed that the optocoupler i am using is not good for high frequency. Below are the results i obtained while trying to switch my 4N26 optocoupler.
The pull up resistor can be reduced to get somewhat better result but the true solution is to use high bandwidth optocuoupler.





In order to see the effect of a high bandwidth optocoupler i recommend to use 6N137. It is an 8 pin optocoupler that can switch upto 10Mbit/sec. For the PV inverter, the isolation can be provided using thi IC. Below is the results of 6N137