Sun's End is a novel by Richard A. Lupoff published in 1984.
Sun's End is a novel in which the main character awakes in 2089 rebuilt as a bionic superhuman with telepathic powers, and is now the wealthiest man in the entire solar system.
[1] Dave Langford reviewed Sun's End for White Dwarf #89, and stated that "Lupoff poses a problem: how to save 26 billion people from dying as the Sun overheats?
He and his hero simply turn their backs on the question.
Thumbs-down to both of them.