All the current items in the personal inventory as it is now...including ship upgrades not already fitted to a ship etc... are to be stored in your personal hangar. It's to bring the personal hangars every ship comes with when purchased, online. That said, I can't remember if the hangars are coming online with 3.15, it may be later.
On first login to 3.15, you'll be asked to chose and confirm your spawn location, not only for placement of your hangar(s) but as a hospital respawn location should you die. Personal equipment such as armour or weapons and ammunition can also be permanently stored in any of your ships. The downside to that is if you die and your ship is destroyed, you'll lose it all.
All paid for personal armour sets and the like will be restocked automatically at your hangar, stuff bought in game will be lost and need to be repurchased with aUEC in game....either that or you fly out, find your corpse and assuming nobody has robbed it, pick up all the gear you were carrying when you died.