Business ideas for a spacious roof top? -

I would like to start a business near our home. My parents own a commercial building just a couple of blocks away from our house and all of the rooms are already occupied except for its spacious roof top... I was thinking of putting up a computer shop there or making it a chill spot for students with billiard tables and all, WITHOUT ALCOHOL, but I don t know, I am still sure of what to put up. I would need some ideas... help me please.

Use it to generate solar power