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Embedded (Distribution-Connected) Variable Generation

Ontario's energy needs are in part being met by small-scale generation located within distribution networks. This increasing amount of embedded generation is reducing the amount of energy needed from the grid to serve local communities and is changing the way the IESO operates the system.   

Growing Impact of Embedded Solar and Wind Generation

Solar and wind facilities located in the service territories of local distribution companies are  contributing to broader provincial needs  with solar generation, in particular, working to reduce summer peaks when air conditioning use is at its highest. By producing electricity closer to where it's consumed, embedded generation has the added benefit of relieving congestion along the transmission lines and reducing line losses.

At the end of 2015, there were nearly 3,000 megawatts (MW) of IESO-contracted embedded generation helping to meet Ontario's electricity needs.

Impact of Solar Embedded Generation on Provincial Demand Row of solar panels


On a sunny day, the increase in morning electricity demand is less than on a cloudy day, as electricity produced by the sun's energy provides for greater levels of local needs.

Forecasting Embedded Generation Output​

The IESO takes into account the increasing levels of local generation as it operates the provincial grid. Just like grid-connected wind and solar generation that is connected to high-voltage transmission lines, these facilities are variable, which means their output levels change according to the availability of the wind or sunlight. By putting in place a forecast for embedded wind and solar generation, the IESO has a more accurate picture of the whole power system. Better and more accurate information means better and more efficient decisions when operating the grid.

The IESO is now actively registering all embedded variable generators equal to or larger than 5 MW with its centralized forecasting service. This forecast is published as the Variable Generation Forecast Report. It includes a forecast of all transmission-connected variable generation and a forecast for embedded variable generation that is currently registered with the IESO.

As of March 2016, about 1,260 MW of embedded wind and solar generation are reflected in the centralized forecast. For more information on data requirements, operational monitoring, training and registration with the centralized forecasting program, see Centralized Forecasting. Generators (and LDCs with embedded generators) can contact Customer Relations for more information.