New BT/EE Hub connection lost

HELP - I have a new BT Hub and have managed to get everything in the home changed over apart from the link with my inverter using the Givenergy app. I cannot find how I apply the new "key". Can anybody help me (in simple layman terms) as to how I can reconnect to be able to control the Inverter/Batytery settings. Thank you in advance.

johnnutton search the forum for new WiFi, should be many threads to choose from.