It has been rumored that the man who became Illuminate was working in a nuclear power plant and was exposed to some strange form of radiation. It's also been rumored that he was a test subject in a secret government laboratory somewhere. The stories all vary, but the fact remains, he was an ordinary man who suddenly had extraordinary abilities.
The most obvious of these abilities was his ability to glow. Wherever he was present, darkness could not exist. And it wasn't a power that he could turn off. His skin always shone brightly. When he first appeared in public, there was speculation that he could be emitting some kind of radiation himself. But that fear was dispelled by the guys in the hazmat suits with Geiger counters.
Whatever powers his luminescent skin also gives him the ability to fly. It wasn't long before the public discovered that Illuminate had other powers. These powers made him a little more dangerous in the people's eyes.
Illuminate reportedly stopped a mugger who had been attacking a young woman in Philadelphia. In his anger, Illuminate's skin grew so bright that it temporarily blinded both the attacker and his victim. The super powered man grabbed the mugger by the arms to pull him away from the woman. Doctors later reported that the criminal suffered from second degree burns on his arms which looked remarkably like hand prints.
Some people were grateful that the world now had a real super hero. Others were afraid. Those who feared Illuminate included some of the country's top government officials. While it was easy to agree that Illuminate was only trying to help, many people wondered what would happen if his powers continued to increase in intensity. Many asked what would happen if he was no longer able to control himself or his abilities.
Illuminate knew of the people's fears. He may not have known anything of his life before gaining his powers, but he had to believe had was a good man. He only wanted to help those who were unable to help themselves. But not at the cost of their comfort or safety. So he made a decision.
After only a few months in the public eye, Illuminate handed himself over to authorities. He asked them to keep him in a safe place. Not for his own safety, but for the safety of the world at large. He knew he was somehow able to manifest a seemingly endless supply of energy. Thus, he voluntarily became a human power plant, providing free energy to most of the eastern seaboard.
No one in the media has had access to the mysterious Illuminate. It can only be speculated that he is being treated well in a secret facility as he continues to give of himself to keep the lights on.