I have see the subpanels in the attic but service panels once a while not very often due the POCO regulations plus local insepctors may have issue with nonOCPD'ed service entrance conductors in the attic space.

BTW Wisconsin say unfused service condutors are limited to 1.5 meter {5 feet} max

France - rather have all it outside much as possible but only allowed indoor short as possible

Unless you have main disconnection outdoor then after that it pretty much unlimited.

Merci,Marc

Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)