How many solar panels does an average Ontario home need?

About eighteen 440 W panels, which is a 7.9 kW array. That comes from two published figures. The Ontario Energy Board defines a typical residential customer as using 750 kWh a month, or 9,000 kWh a year. Natural Resources Canada puts a south-facing Toronto array at 1,163 kWh a year for every kW installed. Nine thousand divided by 1,163 is 7.74 kW, and 7.74 kW of 440 W modules rounds up to 18 panels. Your own bill is the number that matters, though, and it is the first field on the calculator for that reason.

Where do I find my annual kWh?

On your hydro bill. Most Ontario utilities print a twelve-month usage history or a bar chart of monthly kWh, and adding those up is the most accurate input this calculator can take. If you only have one bill, multiply that month by twelve and treat the answer as rough, because Ontario homes swing hard between an air-conditioned July and a dark December.

Should I size the array to cover 100 percent of my usage?

Usually at most that, and rarely more. Under an Ontario net metering agreement the credit for power you export is applied against the electricity you consume, and any credit still unused after twelve months is reduced to zero. So a system generating well beyond what the house uses is buying capacity whose output expires. Sizing at or a little under your consumption is the common advice, and the slider in the calculator is there so you can see what a smaller array costs you in coverage.

Does the panel wattage change how many I need?

Directly. The array size in kW is fixed by your consumption and your location; the panel count is just that size divided by whatever each module produces. A 7.74 kW array is 18 panels at 440 W but 20 at 400 W. Higher-wattage modules mean fewer panels and less roof for the same output, which matters when roof area is the constraint rather than budget. The three options here are real modules: Silfab's SIL-440 QD and Canadian Solar's HiKu CS3W-455MS both publish their own specifications.

Why does the calculator give a range for what the array generates?

Because Natural Resources Canada gives one. Its photovoltaic potential figures already apply a performance ratio of 0.75 to cover inverter and weather losses, and NRCan states that most systems land within about 10 percent of the published value. Printing a single number would be claiming a precision the source does not offer. Snow cover, a dirty array, a partly shaded roof and an unusually cloudy year all sit inside that band.

Will the panels I need actually fit on my roof?

That is a separate question and it is the one that most often forces a smaller system. Eighteen 440 W modules occupy about 378 square feet of bare panel, but a real array needs room between rows and clear of vents, chimneys and valleys, which is why array density on a roof runs 15 to 20 watts per square foot rather than the roughly 21 the module footprint alone suggests. Our roof size tool works that out both ways round.

How many solar panels do I need?

Two numbers decide it: how much electricity your house uses in a year, and how much a kilowatt of panels produces where you live. The second one is published by Natural Resources Canada for every municipality in the country. The first one is on your hydro bill.

Last updated August 25, 2026By The SolarPanelFinder Rooftop Desk

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So the short answer for an average Ontario house is about 18 panels. But average is doing a lot of work in that sentence, and a house with electric heat, a heat pump or an EV can use double the typical figure. Put your own annual kWh in below.

How many panels does your house need?

Electricity you use in a yearIt is on your hydro bill. The OEB treats 750 kWh a month as typical.Where the house isSets the yield figure from the NRCan table.Panel sizeShare of your use you want coveredGoing far above 100% throws credits away. See below.

For 9,000 kWh a year in Toronto

18 panels - a 7.92 kW array

That is 18 modules of 440 W each. Whole panels only, so the array lands a little above the exact size you asked for and covers about 102% of what the house uses.

Electricity you want the panels to cover: 9,000 kWh
Annual output per kW installed in TorontoNatural Resources Canada, south-facing at latitude tilt: 1,163 kWh
Array size that works out to, before rounding: 7.74 kW
Rounded up to whole 440 W panels: 18 panels = 7.92 kW
What that array should actually generateNRCan's stated margin, about 10%: 8,290–10,132 kWh

Sizing past what your home uses is rarely worth it in Ontario. Under a net metering agreement the credit for surplus power is reduced to zero after twelve months, so generation you never consume expires rather than accumulating. The panel count is also a capacity answer, not a roof answer: check the array fits before you order it.

The method

Why your own bill beats any average

The yield figure is published and stable. Your consumption is neither, and it is the input that moves the answer most.

The generation half of this calculation is unusually solid. Natural Resources Canada models photovoltaic potential on a two-kilometre grid across the whole country and publishes an annual figure per municipality, defined as the expected lifetime average production per kilowatt of installed DC capacity. It already applies a performance ratio of 0.75, which covers inverter losses and the fact that a panel in a Toronto July is hotter and slightly less efficient than the same panel under test conditions. The spread across the GTA is small: Milton is 1,152 and Oshawa 1,167, against Toronto's 1,163.

Consumption is where houses diverge. The Ontario Energy Board reaffirmed 750 kWh a month as its standard definition of a typical residential customer in its 2023 review, and that is a reasonable default for a gas-heated house with ordinary appliances. It is a poor default for a house with baseboard electric heat, a cold climate heat pump, a hot tub or a car charging in the driveway, any one of which can push annual use past 15,000 kWh. That is the difference between 18 panels and 31, so the twelve-month total from your own bill is worth digging out.

One more thing shapes the answer, and it is specific to Ontario. Net metering credits you for exported power against the electricity you consume, but the Ontario Energy Board is explicit that unused credits are reduced to zero after twelve months. An array sized well past what a house uses therefore generates surplus that expires rather than banks. That is why the coverage field defaults to 100 percent rather than to the largest array the roof will take, and why an installer proposing something much bigger should be asked to explain what happens to the extra.

Frequently asked questions

How many solar panels does an average Ontario home need?: About eighteen 440 W panels, which is a 7.9 kW array. That comes from two published figures. The Ontario Energy Board defines a typical residential customer as using 750 kWh a month, or 9,000 kWh a year. Natural Resources Canada puts a south-facing Toronto array at 1,163 kWh a year for every kW installed. Nine thousand divided by 1,163 is 7.74 kW, and 7.74 kW of 440 W modules rounds up to 18 panels. Your own bill is the number that matters, though, and it is the first field on the calculator for that reason.
Where do I find my annual kWh?: On your hydro bill. Most Ontario utilities print a twelve-month usage history or a bar chart of monthly kWh, and adding those up is the most accurate input this calculator can take. If you only have one bill, multiply that month by twelve and treat the answer as rough, because Ontario homes swing hard between an air-conditioned July and a dark December.
Should I size the array to cover 100 percent of my usage?: Usually at most that, and rarely more. Under an Ontario net metering agreement the credit for power you export is applied against the electricity you consume, and any credit still unused after twelve months is reduced to zero. So a system generating well beyond what the house uses is buying capacity whose output expires. Sizing at or a little under your consumption is the common advice, and the slider in the calculator is there so you can see what a smaller array costs you in coverage.
Does the panel wattage change how many I need?: Directly. The array size in kW is fixed by your consumption and your location; the panel count is just that size divided by whatever each module produces. A 7.74 kW array is 18 panels at 440 W but 20 at 400 W. Higher-wattage modules mean fewer panels and less roof for the same output, which matters when roof area is the constraint rather than budget. The three options here are real modules: Silfab's SIL-440 QD and Canadian Solar's HiKu CS3W-455MS both publish their own specifications.
Why does the calculator give a range for what the array generates?: Because Natural Resources Canada gives one. Its photovoltaic potential figures already apply a performance ratio of 0.75 to cover inverter and weather losses, and NRCan states that most systems land within about 10 percent of the published value. Printing a single number would be claiming a precision the source does not offer. Snow cover, a dirty array, a partly shaded roof and an unusually cloudy year all sit inside that band.
Will the panels I need actually fit on my roof?: That is a separate question and it is the one that most often forces a smaller system. Eighteen 440 W modules occupy about 378 square feet of bare panel, but a real array needs room between rows and clear of vents, chimneys and valleys, which is why array density on a roof runs 15 to 20 watts per square foot rather than the roughly 21 the module footprint alone suggests. Our roof size tool works that out both ways round.

Sources

Where these figures come from

Natural Resources Canada, Photovoltaic potential and solar resource maps of Canada - annual kWh per kW installed, per municipality, and the 10% accuracy statement
Ontario Energy Board, Defining Ontario's Typical Residential Electricity Customer (2023 update) - 750 kWh a month as the typical residential consumption
Ontario Energy Board, Net metering - how credits work and the twelve month expiry
Silfab Solar, SIL-440 QD - 440 W at 1721 by 1133 mm
Canadian Solar, HiKu CS3W-MS datasheet - 430 to 455 W at 2108 by 1048 mm

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