Capacity factor is the electricity a power plant actually produces over a year, divided by what it would produce running at full power every hour. Wind farms in Canada typically land somewhere around 30 to 40%, because the wind doesn't always blow at full strength. That doesn't mean turbines sit idle two-thirds of the time. They generate at partial output most hours, and capacity factor is just one of several numbers needed to compare energy sources fairly.
Key takeaways
- Capacity factor = actual annual output ÷ (rated capacity × 8,760 hours).
- Canada's wind fleet averages roughly 30% or a bit more; newer turbines at good sites often do better.
- Turbines produce some electricity most of the time, just rarely at full rated power.
- Every energy source has a capacity factor below 100%, including nuclear, hydro and gas.
- Cost per unit of energy, reliability and grid fit matter more than capacity factor alone.
The basic formula
Capacity factor compares real output with theoretical maximum:
Capacity factor = energy produced in a year ÷ (rated power × 8,760 hours)
Example: a 4 MW turbine running flat out all year would make 4 × 8,760 = 35,040 MWh. If it actually produces 12,300 MWh, its capacity factor is about 35%.
A quick estimate for Canada
We can roughly estimate the national figure using public data. The Canadian Renewable Energy Association reported nearly 19 GW of installed wind capacity at the end of 2025, and Statistics Canada reported wind generated about 50.5 million MWh (50.5 TWh) in 2025.
- If roughly 18.5 GW was operating on average through the year: 18.5 GW × 8,760 h ≈ 162 TWh possible.
- 50.5 ÷ 162 ≈ 31%.
This is a back-of-the-envelope figure, since capacity was added through the year and output varies by region, but it's in line with typical onshore wind performance.
Why wind farms don't run at 100%
The wind varies
A turbine reaches its rated (maximum) power only at fairly strong wind speeds, often around 11 to 14 m/s. Below that, output drops quickly, because power rises with the cube of wind speed. Most hours fall somewhere in between. Our guide to how wind turbines work explains cut-in, rated and cut-out speeds.
Very high winds
In storms, turbines shut down to protect themselves.
Maintenance and outages
Scheduled maintenance and repairs take turbines offline, though modern wind farms are typically available more than 95% of the time.
Curtailment
Sometimes the grid can't take all the power, because of transmission limits or low demand, or turbines are slowed to protect bats during migration (see wind energy and wildlife).
Icing
In Canadian winters, ice on blades can reduce output or trigger shutdowns, though winter is often the windiest season.
Capacity factor isn't the same as "running time"
A common myth is that a 33% capacity factor means turbines run only a third of the time. In reality, a well-sited turbine generates some electricity most hours of the year. It's just usually below full power.
| Measure | What it tells you | Typical wind value |
|---|---|---|
| Capacity factor | Average output vs. maximum | ~30–40% onshore; higher offshore |
| Availability | Share of time the turbine is able to run | Often 95%+ |
| Hours generating | Share of hours producing any power | Often well over half |
How other sources compare
| Source | Typical capacity factor range | Main limiting factor |
|---|---|---|
| Nuclear | ~80–90%+ | Refuelling and maintenance outages |
| Hydro (reservoir) | ~40–60% (varies widely) | Water availability, operated to follow demand |
| Natural gas (peaking) | Often below 15% | Runs only when needed |
| Natural gas (combined cycle) | ~40–60% | Fuel cost and demand |
| Onshore wind | ~30–40% | Wind variability |
| Offshore wind | ~40–50%+ | Wind variability (steadier winds) |
| Solar PV in Canada | ~12–20% | Night, seasons, clouds, snow |
Values are approximate ranges. Low capacity factors aren't always a sign of weakness. Gas peaking plants have low capacity factors by design, and hydro dams often hold back water for when it's most valuable. See our hydro guide and the related post on how hydroelectricity works.
Why capacity factor still matters
- Sizing: to produce a given amount of energy, a wind farm needs more rated capacity than a nuclear plant.
- Costs: higher capacity factors spread fixed costs across more electricity, lowering cost per kWh.
- Siting: developers chase sites with stronger winds to raise capacity factors.
- Technology: taller towers and bigger rotors have pushed capacity factors up over time, because they capture more energy in moderate winds.
Making variable power work on the grid
Grid operators plan for wind's variability using:
- Geographic diversity: wind farms spread over large areas don't all slow down at once.
- Forecasting: wind output can be forecast hours to days ahead.
- Flexible partners: hydro reservoirs, batteries and gas plants fill gaps.
- Transmission: linking regions smooths supply and demand.
Canada's large hydro fleet makes it especially well suited to integrating wind. Explore more on our wind page and the glossary.
Frequently asked questions
Is a 35% capacity factor bad?
No. It's normal for onshore wind and reflects the nature of the resource, not inefficiency. The more relevant question is the cost of the electricity produced, which for wind is competitive with other new generation.
Why do offshore wind farms have higher capacity factors?
Winds at sea are stronger and steadier, with nothing to slow them down. Offshore turbines are also larger. Read about offshore wind in Atlantic Canada.
Does capacity factor change from year to year?
Yes. A calm year lowers wind output, and a dry year lowers hydro output. That's why long-term averages are used for planning.
The bottom line
Capacity factor is a useful measure of how much energy a power source delivers compared to its maximum, but it's easy to misread. Wind farms in Canada typically produce around a third of their theoretical maximum because wind varies, and they still generate power most hours. Combined with Canada's hydro and growing storage, that variable output is a valuable part of a clean grid.
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