Well the one is stealing which will get noticed if you consume a significant amount and the other.
And solar power panels are still too expensive their roi is even worse than the mining rigs and I doubt that anyone who writes here and claims free electricity has a high end solar system.
Define "a significant amount", it doesn't matter if you've got 1 person running 20Ghash or 40 people just running 500Mhash each, the latter probably won't be noticed by landlords or universitys especially if they live in a large dorm where it's split between say 10 people. I get free electricity in that I don't have to pay it, but be welcome to not believe me it doesn't matter to me if you do.