You have 2 options:
1. Install backup cilinderspack/trailer and a H2 compressor and compress a part of the H2 product from the PSA in the backup cilinders.
2. Install a backup cilinderpack/trailer who will be supplied by an gascompany (like Linde or AirProducts)
With option 1 you have to invest yourself in expensive hardware. (cilinderpack or trailer and a H2 compressor). Because your working with H2, the costs will be high.(special materials, safety)
With option 2 you rent the trailer from your supplier. You don't have to invest in the filling part, the H2 compressor. It keeps it more simple and more cheap.
To make the discission in option 1 or option 2 you have to consider how often the PSA goes offstream. How often will you use the backup installation.
An other thing is: Do you get permission to install a pressurised H2 backup installation on your premises?
I'll advice you to ask you local authorities what the rules are for that.
A large volume of pressurised H2 is different then producing H2 onsite with a PSA-unit.
Good luck
Cryotechnic.
"Math is the ruler of your potential succes...."