With the XP300U, the fan runs permanently as soon as the solar panel is plugged in, which was not the case with the XP300.

Here are the answers I received:

The provider could not give me the answer, but I managed to find the information online :

The Xtorm XP300U is the successor to the popular XP300 and now features the X-Charge function for up to 33% faster charging.

So the article: Xtorm Power Station XP300U 78 Ah is the successor of Xtorm Centrale électrique portable XP300 and integrates the X-?

Charge for up to 33% faster charging.