Armor which has been unequipped still charges. Burner generator equipment is not currently supported. Any other equipment types should be supported. Solar panels are charged assuming a 70% average efficiency based on the normal Nauvis day/night cycle.
Armor can only tracked by using the unique item_number property, so in order to start being tracked, one of three situations MUST occur:
1. the armor must be equipped/unequipped by a player, either when the mod is first loaded or any time after OR
2. the armor must be in a player's inventory when the mod is first loaded OR
3. the armor must be opened while the mod is loaded.
Newly crafted armor is not tracked. In vanilla, this shouldn't matter since it wouldn't have any equipment in it TO charge anyway, and if you open it to add equipment it starts being tracked.
Due to engine limitations armor is only updated when it has been re-equipped or opened. I'm not aware of any other situation in vanilla where it would actually matter, but interactions with scripts may break this.