im changing my wifi router next week do i need to do anything ?
im sure the installers asked for the wifi passwords when setting it up ?
im changing my wifi router

xander best thing to do is when you set up the new router, change the SSID (network name) to what your old one was and keep the same password. Everything, not just the inverter, will reconnect!
Find the IP of the inverter on the current router
http://<that-IP> in your browser, login with admin/admin (i'll bet its not been changed)
Go to the menu option AP Interface - note down its SSID (Network name) and set a password. (this possibly hasn't been done and could be opening your network up to the outside)
That'll allow you to get back into the device directly after changing your router.
Then from the menu options for STA Interface, you can see and update the SSID and pass phrase of your new router.
The easiest option as mentioned above is change your new routers details to the old details.
But if you do decide to do otherwise, this guide may be of use https://kb.givenergy.cloud/article.php?id=1
Perhaps check that you can access the inverter's own access point, so you have another way in if there are problems.