Each week Ontario's Independent Electricity System Operator (IESO) publishes a report, with selected metrics for the week (IESO uses Wednesday as the first day of a week). This page contain my estimates of many of those same metrics, and additional metrics either to provide a comparative context, to the prior year, or to provide information on supply mix issues, including estimates quantifying the generation curtailed in Ontario, and the generation, and costs, of distributed generation.

The import/export figures graphed here are from the "Hourly Import Export Schedules" file (as updated weekly). These figures also match the IESO's weekly reported, as demonstrated by comparing the figures in the next table, for the current year, to the IESO weekly report.

The figures in the IESO's "Hourly Import Export Schedule", update weekly, do not always match the figures in the IESO's "Intertie Schedule & Flow Report", which is updated hourly - in fact there is a frequent variance in exports moving through the interties.

Evidence strongly suggests the difference in the two IESO data sets is primarily hydroelectric production that is fed directly into Quebec's grid. It is unknown how, or if, Ontario is compensated for curtailing the supply on it's grid by feeding output directly into Quebec's. When Quebec's reservoirs are low this may be Ontario's preferred supply curtailment option, but it's also used to boost exports (in winter - as Quebec is a winter peaking jurisdiction).

Other known maneuvers occur at Bruce B reactors (steam bypass), and paying non-utility generators to go offline. These curtailment actions are estimated on the following graph, as negative values, and shown along with wind output. Again, the approach is simply programmed to show when generators are operating in the range they would be operating in during curtailment.

Curtailment that is more difficult to track include: the total removal from service of nuclear reactors during high supply/low demand periods, and the economic curtailment of hydro-electric sites.

Wind generation (Tx) is included here because it's important to note that, while it is frequently cited as being important in replacing coal, Ontario continued to add industrial wind turbines after coal-fired generation was eliminated. We do frequently have more baseload supply than our domestic market can handle - and curtailment actions indicate we also increasingly have more supply than export markets are willing to absorb.

Baseload takes a number of forms in Ontario: including nuclear that has the same costs at full output as at reduced output (probably less), run-of-the river hydro with a fixed cost, and sources that are contractually guaranteed payment for supply whenever it is produced. These sources are not only the newer solar and wind contract holders, but historical non-utility generators (NUGs). The following graph shows the hourly contribution of sources I have considered baseload, and all other sources I feel capable of creating estimates for, based on IESO data:

Simplified, graphing only the 'baseload' generation, as indicated in the preceding graph, against Ontario Demand is the simplest graphical indication of the Surplus Baseload Generation condition - although it is still imperfect, as water conditions also determine what the 'baseload', or minimum generation without spilling, is for hydro, and many thermal plants may be more efficiently run overnight, than stopping and starting only during demand spikes during the daytime periods.

I updated this graph (September 24, 2014) to show both the produced baseload power, and the total inclusive of my estimates of baseload generation that was curtailed. This gives a better picture of the surplus that must be dumped on export markets, or paid to forego production.

The next graph illustrates the differences in weekly supply, and demand, over the same week in the previous year. Net Imports are almost always negative in Ontario (only one day in nearly 18 months saw total imports exceed exports), so when the change in net imports is positive, it indicates reduced exports. Similarly, a reduction in Ontario Demand is shown as a positive "Demand Reduction" figure. Along with changes by different fuels sources, this produces a graph that essentially balances the growing, and declining, elements of the system.

The following graphs have been added to this page since week 18 of 2014. The first graph includes estimated values for embedded generation for solar, and wind.

Ignoring embedded generation is a growing weakness of official Ontario reporting as solar is now impacting market pricing, and reported demand (the untracked embedded generation reduces what the IESO reports as demand). The solar estimates are based on day-ahead "Variable Generation Forecasts" from the IESO along with estimates of how much capacity is considered in those estimates, and how much overall solar is estimated to be contracted and in service (by the OPA).

There is also a growing amount of "embedded" wind capacity in Ontario - which I've estimated as 12.5% of the figures reported by the IESO.

The reason the estimates for solar and wind are particularly apparent if estimates are shown for hourly costs - in the same format. There is little reporting on solar generation; what reporting there is indicates that in 2013 total solar generation was 0.8% of Ontario supply (OEB) and the cost of procuring that 0.8% was ~5.1% of total supply costs ("Generation Cost by Resource" tab of OPA "Cost of Electricity Service" spreadsheet).

2016 Addendum

The following charts display data for the same 7 day week in previous years. The IESO's weekly reporting starts each Wednesday, so the n^th week of a year is the week beginning on the n^th Wednesday. Showing the data for the same week over a six year period will demonstrate changes in supply mix and the cost of electricity supply to the various market segments.

The supply demonstrated here includes estimated distribution connected (Dx) generation as well as IESO grid-connected (Tx) and curtailed generation. Not estimated is curtailed public hydro.

The total cost of the supply charted above is estimated as:

The supply priced above either services "Ontario Demand", export markets, or is curtailed (generation is cut). The chart below reflects the same data as the chart above. Note that Ontario Power Generation reports 3.2 million megawatt-hours of hydro-electric generation was curtailed in both 2014 and 2015. I do not estimate that curtailment, so the charted value is very conservative:

Consumption of supply is slightly different. "Ontario demand" includes generation lost in transmission, and generation that powers generators. Monthly "Consumption" is provided by the IESO upon requests, and is something I estimate as it is necessary both for rate calculations and to determine the cost impact of "Class A" consumers (background here). These consumers were limited to consumers with a monthly peak demand over 5 megawatts, but the threshold was lowered, for some industries, to 3 MW as of July 2015.

Costs are not evenly distributed. Exported supply gets what the market can attain while Ontario consumers pay the full cost of supply through the global adjustment mechanism - a mechanism designed to transfer costs from Class A consumers to everybody else (Class B).

Rates can vary greatly between consumer classes:

Class B consumers, which include residential consumers on the regulated pricing plans that reflect forecasts of Class B commodity costs, pay the average cost of supply plus an amount to compensate for exporters, and Class A consumers, generally paying less than the average cost of supply:

Weekly reports are not archived in this format, but the weekly spreadsheets with the embedded data, and graphs, are archived in this folder.