Cracked heels are caused by more than just overexposure and lack of moisturizing. Cracked heels are a sign that you are deficient in zinc and omega-3 fatty acids.
Home remedies for cracked heels
Before bedtime, wash your feet with warm water and dry them. Liberally apply petroleum jelly on your feet, massaging it into the rough and cracked areas. Wrap each foot with plastic wrap. Put socks on and sleep that way. Repeat the process nightly until your feet are fine. It shouldn't take more than a week... probably less.