The Independent Electricity System Operator and transmitters work together to ensure energy is connected and transmitted reliably and safely across the province. The Independent Electricity System Operator is responsible for ensuring overall system reliability and for balancing both supply and demand for the province in real time. It is also responsible for forecasting demand and supply of electricity, and for rules, settlements and financial operation of the $13-billion wholesale electricity market.

The Independent Electricity System Operator's role in the FIT Program is to assess and provide approval to connect a renewable energy project to the high-voltage transmission system.

There are six transmitters in the province, the two largest being Hydro One, with 29,000 kilometres of high- and low-voltage transmission lines, and Great Lakes Power, with 644 kilometres of high-voltage transmission lines. Ontario's other transmitters are Canadian Niagara Power, Five Nations Energy, Cat Lake Power Utility Limited and Niagara West Transformation Corporation.

Transmitters work with FIT Program participants to complete their system connection.