So it's going to take like 3 feats to fix this.
Combat Casting
Uncanny Concentration
Additional Traits (including Desperate Focus or Focused Mind)
Hmm.. that's +8 to your Concentration roll.
So assuming you are Level 1 with a +3 stat...
1d20=1 roll+8 feats+1 level+3 stat=13
Doesn't quite get you to 'always succeed' on a DC 17 Concentration roll.
At level 9 with a +6 stat...
1d20=1 roll+8 feats+9 level+6 stat=24
DC for level 5 spells is 25 so you are almost there...
At level 20 with a +8 stat...
1d20=1 roll+8 feats+20 level+8 stat=37
DC for level 9 spells is 33, so you are good at that point... but not by a huge margin.
What's the effect of a 1 on a Concentration roll?