Electrical consumption of a hard disk

[tina2801]

Good morning all

I will create a NAS from a server.
There should be 10 or 15 disk in it.

as I must sizer at best and it is a machine that will turn 24/24 (with the cons that goes with) I must know if the current power supply is sufficient.

so my question is this
on average how much can we estimate the consumption of a disk
3.5 "
2.5 "mechanical
2.5 "SSD

thanks in advance