with regards to the death of superman. that was the reason he didnt die, b-cuz he had absorbed so much solar energy his body was still alive after his brain function ceased. since when does superman have limits?
in the Else World title Superman:The Darkside. supes needed more solar energy to deafeat darkseid and light ray, of the new gods scarificed himself by giving superman his life essence, thus making him stronger. so it trluy makes sense that continued exposure to solar energy would make him even stronger.