That depends, full AC draws 5kw for me, so you'd need probably a 10kw system to get coverage for most of the day, and that's a big one, I think requiring a 3 phase connection. I dare say unless you have a fortunate roof shape (all flat or pointing all the right way) you wont be able to fit that on either..

Ah yes, I was being too loose in my language. I should have said: "gets my father enough credits, so HE does not worry about the costs of running the AC", which upon reflection might only be during and and the evenings"