...Because Solaris believed he was firing a k-nite bullet into the Sun... And believed this would kill Prime... And believed his death would end the Dynasty.
If anything that just proves Prime himself was the battery.
__________________
"I am tired of Earth. These people.
I am tired of being caught in the tangle of their lives."
Also, are we really trying to act like Prime himself can't just amp the Dynasty whenever he feels like it?
ie. even IF the Super Sun itself were the Dynasty's sole battery in the 853rd century, and even IF, say, Prime and Kal ventured to another era and Kal's powers began to wane... Do you really think that Prime couldn't simply bring him back up to full power with a gesture?
Rhetorical question: we know he can. We saw him do so on panel, when he originally bestowed said amp to the Superman of the 700th century.
__________________
"I am tired of Earth. These people.
I am tired of being caught in the tangle of their lives."