I understand that the isolation transformer can convert the voltages, but does it also alter the frequency? For example 230V (50Hz) to 120V (60Hz)? This one is important because the frequency will affect my devices that require 60Hz if they are getting 50Hz.
If the isolation transformer does not change the frequency, what can I use to change the frequency?
You don't really need to change the frequency. Most 60Hz appliances will run on 50 Hz - only motor driven appliances will work a little more slowly. If you do need to change the frequency, then you need to separate the charging function from the inverter function - so all your power flows through the DC bus, always. Only other alternative is a rotary converter.
Transformers do not change frequency.
As @Mike Dorsett pointed out most things will be fine with a different frequency but check your devices.
If you need frequency conversation then you will need to go
Grid -> Charger -> Battery -> Inverter -> loads.
You will need a separate Charger and inverter as the inverter can not connect to grid when outputting a different frequency than grid connection.
on a multiplus the frequqncy that enters is the one that goes out since there is a passthrough mode. but when in inverter mode then you can choose the 60hz. but the transformers can not do that. sorry
