Transfer BTC between two wallet in two different devices? I have to format my pc, so I have downloaded a BTC wallet also on my tablet. Is there a way to send BTC without commission fees?
It might be possible to export the private keys from your PC wallet and import them into your tablet's wallet. The details and practicality of this would depend on which wallet software you are using at each end.

It would certainly be easier just to create an address on the tablet and send all the coins there. You may have to pay a transaction fee (most people don't call it "commission") but it's not likely to be more than a few pennies.