I would be hanging on for them to fit what they quoted, if you go into the Inverter to wire a socket you are leaving yourself open to invalidating the warranty claims. I have a query over the way ours will work, I was assured that in the even of failure our power would stay on up the the capability of the battery, I was expecting either a manual or automatic isolation switch, but he is claiming it's not required. Currently I don't see how all our stored electricity will not be just sucked straight up the road, but waiting until it's fully commissioned before further questions.
Our is still not up & running correctly the panels are producing electricity which we are using, but the battery charger is still not talking to the battery as the firmware on the charger & battery are different, they have fitted the dongle to the charger but all attempts to talk to it have failed, they need a Growatt installers code, the ones they have registered to them don't work.