User blog comment:FairyRaven/Fairy Tail Chapter 368: The Third Seal, Review and Commentary/@comment-24066070-20140127014759/@comment-24066070-20140128202953

I re-read the page of the chap and it clearly says 500 times the power of Jupiter. (MangaHere version of the chap)

Imagine 500 GH ships floating around Magnolia, all firing their Jupiter. Would certainly redecorate the landscape.

But it is indeed strange why it would need to be installed in the guild. I'd say anywhere in Magnolia would be fine.