Ontarians use more than 140 million megawatt hours of electricity a year. Ensuring that there is enough energy to meet that demand is an ongoing and highly-complex process, requiring the close co-ordination of all parts of the system. The IESO is at the centre of it all, directing the flow of power across the province. This section provides an overview of Ontario's power system— from the first flick of a light switch to the final statement on the electricity bill —
and everything in between.