you need to allow for replacement of the springs once every five years at least.
The hinge (end of blades) is polyurethene now so should not need replacing until 10 - 15 years old.
Blades need replacing only if you are unlucky to have them damaged by being hit by something (very expensive).
Glad you found the photos useful.
Are you going for a grid connected system? Do they allow that in Ireland yet?