The first dungeon I solo'd was Normal Darkshade Caverns 1, you could try that one.
Fungal Grotto, Spindleclutch, Banished Cells, Darkshade Caverns, Elden Hollow, and Wayrest Sewers (all normal version 1) all seem about the same difficulty, solo-wise, so those would be good ones to work with before moving onto the others
Try Volenfell. There's a trick to the final Boss. Out of the three Centurions, one of them stays in one spot as it fires off shock artillery at you. Those bolts have a limited range, which you're safe from in the back of the room. If you keep the fight back there the bolts can't hit you so you're only dealing with damage from the two that chase you. Once you've finished the two, the last one only has about 30% health left since they all share a health pool.
I did Solo things as well on this Sorc "tank" I'm trying to level. Around level 20 I did the first 3 dungeons on normal, so maybe just go for the other two now. If you are patient try wayrest normal. That is an easy enough place.. right?
Video below for some non-entertaining proof, but Sorcers have an unfair enge with their Pets and PvE gameplay.