The only wormholes you can solo are class 1 and 2 with 3 being a possibility. For the 1s and 2s a Drake is plenty of firepower and tank to handle the sites. You may run into problems if you happen to get a good number of repping sleepers in a wave, but you should be able to overcome them with patience.
One thing to remember though is the wormholes are bound by a maximum jump mass so you may not be able to get a battleship into a class 1 or 2 from empire. If you're already in W-Space this is easier, but can still be a issue. Be sure to check the mass restrictions and limits with wormhole thingie or EVE HQ before doing anything in W-Space.