well that all depends are you hitting it hard on the ground causing loss of momentum or are you getting hurt without loosing momentum?

With: tuck harder
without: u could be rolling a little to far on your side, on the edge of the hip bone.
 there is no magic tip I can give, just adjust, play around with it untill it feels smooth and don't hurt.

Try lying on your back and tuck your arms and legs as if you're in transition state of roll. Think of how you come out of the roll while rocking forward to get up. How does your back touch the ground and which specific part of your body touches the ground before you come out of the roll (is it your hip bone, hip, butt, side or any specific part)? Try to figure out which angle you come out of the roll is optimal for you that won't hurt your hip bone. Then practice the one angle that does not give you any pain.

There are no shortcuts. You're just going to have to drill your rolls on softer surfaces many many times until you get it.

It took me almost a year and a half to get comfortable with rolls on concrete. So just keep working on it.