I have the same issue. But it is the API from Growatt, which (in my case) allow updates every 5 Minutes. For my homeassistant i now use a Smart Plug with support of enery measurement. Works as expected and i get the date nearly in realtime…
Cheers
My experience is different. I set my Shine Wifi X to 1 min interval and am getting 1min updates in HA. Growatt graphs still update every 5min.
One of my mistake I regret since getting access to make changes to the USB dongle is updating the firmware which was available connecting to the dongle directly according to instructions to change the domain to IP to direct traffic to Grott.
After updating to latest firmware, I got locked out and could no longer logon to the local web console, luckily the update setting wasn’t changed but the domain was configured back to the Growatt website and lost the messages sent to Grott.
As a workaround, since I added an entry in my firewalls DNS for server-au.growatt.com to point to my HA, and got the MQTT traffic back once more.