We were on the Grand Princess trans Pacific Sydney to San Francisco last year in April. In Samoa all electricity to section 7 of the ship failed which meant all cabins in section 7 , vista lounge and all public areas at the aft of the ship had no ac , lights anything!….they were unable to fix for 5 days until a part was flown into Honolulu.
Luckily there were enough free cabins for people to be moved….some were moved from suites to inside.
Princess compensated every one on the ship by giving us 50% of our cruise fare as a FCC…I believe those who had to move cabins were given a higher percentage of compensation.
We were in section 6 and ac worked in our area….it was just in the corridors that effected us and not being able to use facilities in the aft of the ship for 5 days. To be honest it did not affect our cruise enjoyment as we just used other areas of the ship. We were very great full for the 50% FCC and felt Princess were very generous.