During the day there is a lot of PV production. The house is empty and a lot of surplus is generated.
The summer sun heats up the house and heat builds up not only in the air but also in the structure.
When people come home in the evening, the house is hot and the air conditioning has to be switched on. There is no more PV production and energy is consumed from the grid (more expensive than the surplus payment).
The air-conditioning is switched on during the day to a greater or lesser extent depending on the available PV surplus. The cool air does not allow “structural heat” to build up.
When people come home in the evening, the house is already cool and there is no need to run the air conditioning.