Talvez tenha sido Fade-Out por Patrick Tilley ?
Alien Day
The date was Friday, the third of August. For some people the day was just beginning. For others it was the end of another perfectly normal day. Then right across the world every ground and airborne radar screen went haywire
This time it had really happened. An alien spacecraft was in orbit around planet Earth. And nine weeks later civilization was on the edge of a total breakdown more devastating than any nuclear war or natural disaster
Esta é uma combinação levemente improvável, porque o efeito da chegada alienígena é perturbar toda a comunicação de rádio (daí o título, Fade-Out, referindo-se a um conceito de comunicação de rádio) ao invés de desativar toda a eletricidade.