Solar Power Tower

The invention of Autobot mechanical artiste Grapple, the Solar Power Tower is an installation for collecting solar energy. Mechanised panels move to maintain an optimum angle depending on the time of day.

Unfortunately it doesn't have any sort of defense against Decepticon attack.

The Transformers cartoon
Grapple and Hoist built a small model of the Solar Power Tower as proof of concept, and the model successfully performed. Unfortunately Optimus Prime denied them permission to build the full tower, on the grounds that it would be indefensible against the Decepticons.

That's where the Constructicons came in. Claiming to have defected from the Decepticon cause, they offered to help the pair build the tower, and provided a pile of energon cubes as proof of their intentions. It wasn't long before the two Autobots were hard at work with the Constructicons, who carefully didn't mention that they were stealing construction materials from the humans for their little project.

Eventually the tower was finished, with just the sun-focussing sphere to place on the top. Though Grapple lamented that he hadn't considered the practical problems of mounting the sphere, the Constructicons merged into Devastator, lifting the sphere into position. And then revealed that they'd never defected from the Decepticons, and were turning the tower over to Megatron.

The other Autobots soon found out about the tower, mounting an attack. With some deft planning, Optimus was able to trick Devastator into destroying the tower himself, and the Decepticons soon fled. The Autobots were left to pick Grapple and Hoist out of the rubble.

Transformers Legends
Grapple and Hoist showed off their Solar Power Tower model to Optimus Prime, but he didn't think the Autobots would be able to defend it against the Decepticons.