So properly you are supposed to have an electrician fit you a separate connection between the consumer unit and any generation equipment, along with a bidirectional RCBO, isolator and correct single line diagram and labelling. You then wire up to 3.68kW of type approved equipment to it and fill in a G98 form and you are done.
In practice people buy stuff like the Ecoflow Stream kit, put a plug on the end of the cable and plug it into the wall and maybe do the G98