Sun-Pak
From Transformers Wiki
The Sun-Pak is an experimental solar battery created by Sparkplug. The Sun-Pak is able to absorb enough energy from one hour of sunlight to power a Transformer for 24 hours!
The Sun-Pak Prototype is made of metal and fiberglass, and secured externally to the Transformer it's powering by means of an electronic lock. As a prototype, the Sun-Pak is not a sealed unit; it can easily be rewired for adjustments (such as increased power output) but this also means that the prototype is not waterproof, shockproof, bombproof, or acid-proof.
Fiction
Attack of the Insecticons
Sparkplug's invention of the Sun-Pak created a power-struggle among the Decepticons to possess its secret.
The Sun-Pak is central to every possible path in Attack of the Insecticons, and so to recount its involvement in this story would simply mean reproducing the entire synopsis of the book. Inasmuch, to find out more about the possible adventures surrounding this device, read about them at the "Attack of the Insecticons" page.