Solar pool

What a solar pool does is not clear, but what is known is that it contains destructive energies within.

Fiction

IDW Generation 1 comics

Garrus-9 had a solar pool. After Nemesis Prime was killed by Galvatron and the Darkness passed on to an unwanting Optimus Prime, Galvatron gave Optimus two options: throw himself into the solar pool or give him the Darkness. Optimus chose both, giving the Darkness to Galvatron and throwing him into the solar pool, seemingly destroying him.

Later, the solar pool proved ineffective as Galvatron emerged from it. Spotlight: Sideswipe