best switch for bidirectional converter

[alo]

i want to do a project regarding creating electrical energy from renewable energy.since renewable energy does not provide a constant input, i use a battery as a back up supply.so if the input higher than the desired voltage level, the voltage should be supply to the battery. on the other hand, when the input is lower, the battery will back up the supply in order to maintain the output level. the desired voltage level is around 200-400V and the battery is 400V. so, the problem is which semiconductor is the best switch to control the flow of the voltage ( in and out of the battery)?

 

[BrownOut]

Connet a diode between the renuable source and the battery. When the renuable source drops .7V below the battery voltage, then the battery will supply the current.

 

[alo]

what kind of diode is the best for that application???
mosfet or igbt???

what if the voltage just around 12V.. what transistor should i used as switch???

 

[tcmtech]

Use a diode with a higher current rating than what amount of amps the device is drawing.

 

[alo]

ok...i have another question...
from my research from the internet, most of high voltage(HV) application pick igbt as the switch...

so, why is igbt always be the device of choice for HV (more than 1000V) and mosfet always br the device of choice for LV(less than 250V)?