Question
The problem: raccoon on our shed roof.
You write of "porcupine strips"?  
What are they?  What is the source for the strips?
Could you diagram how they are used?
Thanks.

Answer
Porcupine wire consists of stainless steel spikes that can be used to prevent climbing animals from climbing. Retail name is Nixalite. Visit nixalite.com

However, they should be used to PREVENT problems. Since you already seem to have a problem, you should first RESOLVE then once the raccoons are gone then use them to help reduce future occurrences.

Details on raccoon control is at http://icwdm.org be sure to read about handling skunks BEFORE YOU BEGIN TRAPPING as they tend to enter traps set for raccoons.
Follow all state and local laws.