Bouff34 It should be handled fine.
The issue is that the Growatt API doesn't allow the overlap from charge schedule finishing at 17:30 and an export window beginning at 17:30.
I tried this out myself and on the web Growatt portal, you get a validation message saying conflicting time or such. I then tried it with the API, and indeed got the Inverter success=failed message.
Moving the export start one minute after the end of the charge window worked fine.
If you had set your export to start at 17:31, you'd have been fine.
Hope that helps!
