Sun's End — Richard A. Lupoff

The last thing computer circuit planner Daniel Kitajima remembered was being hit by a crane at an orbital construction site. Waking up 80 years later - in 2089 - he found that most of his body had been destroyed...but he had survived.

A group of doctors had constructed an artificial body that gave him superhuman strength, the ability to survive without food or air, the powers of radar and infrared vision.

All Daniel wanted was to resume a normal life. But his new-found strengths had attracted the attention of powerful people with a devastating secret - that the solar system only has a few centuries to live...