Most Canadian homes that want to cover their full annual electricity use need somewhere around 15 to 30 modern solar panels. That's roughly a 6 to 12 kW system. To find your own number, divide your yearly electricity use (in kWh) by how much one kilowatt of panels produces where you live, then divide by the wattage of each panel. Your roof space, budget and your utility's net metering rules decide whether you should aim for 100% or less.
Key takeaways
- Start with your annual electricity use. Add up 12 months of bills.
- A kilowatt of well-placed panels in southern Canada typically makes about 1,000 to 1,400 kWh a year.
- Modern residential panels are commonly 400 to 450 watts each and take up about 2 square metres.
- Your utility's export rules matter. Under weak export credits, a smaller system often makes more sense.
- Plan for future loads like a heat pump or EV before you size.
Step 1: Find your annual electricity use
Pull your last 12 months of electricity bills, or download usage data from your utility's online account. Add up the kilowatt-hours (kWh). Many Canadian homes use somewhere around 7,000 to 11,000 kWh a year. Homes with electric baseboard heat, heat pumps, pools or EVs can use far more.
Use a full year, not one month. Usage swings by season, especially if you heat or cool with electricity.
Step 2: Estimate your local solar production
The key number is specific yield: how many kWh each kilowatt of panels produces per year. In Canada, a reasonable approximate range for well-oriented, unshaded systems is:
| Region (approx.) | kWh per kW per year (approx.) |
|---|---|
| Southern Prairies (e.g., Calgary, Regina) | 1,250–1,400 |
| Southern Ontario & Quebec | 1,100–1,250 |
| Atlantic Canada | 1,000–1,200 |
| Coastal British Columbia | 950–1,150 |
| Southern interior B.C. | 1,100–1,300 |
These are rough planning numbers. Your installer should model your actual roof, tilt, orientation and shading. Natural Resources Canada also publishes solar potential maps for municipalities across the country.
Orientation matters. South-facing is best. East- and west-facing roofs commonly produce roughly 10–20% less, which can still be worthwhile. North-facing roofs are usually poor candidates unless the pitch is very shallow.
Step 3: Do the math
System size (kW) = annual use (kWh) ÷ specific yield (kWh per kW)
Number of panels = system size (W) ÷ panel wattage (W)
Example: Toronto-area home
- Annual use: 9,000 kWh
- Specific yield: about 1,150 kWh/kW
- System size: 9,000 ÷ 1,150 ≈ 7.8 kW
- With 420 W panels: 7,800 ÷ 420 ≈ 19 panels
Example: Saskatoon-area home with an EV
- Annual use: 11,500 kWh
- Specific yield: about 1,300 kWh/kW
- System size: 11,500 ÷ 1,300 ≈ 8.8 kW
- With 430 W panels: 8,800 ÷ 430 ≈ 21 panels
Example: Halifax-area home, east–west roof
- Annual use: 8,000 kWh
- Specific yield: about 1,100 kWh/kW, minus roughly 15% for orientation ≈ 935 kWh/kW
- System size: 8,000 ÷ 935 ≈ 8.6 kW
- With 410 W panels: about 21 panels
Step 4: Check your roof space
Each typical residential panel is about 1.7 by 1.1 metres, or roughly 2 square metres. Twenty panels need about 40 square metres of usable roof, plus setbacks. Many building and fire codes require clear pathways around the edges and ridge of the roof, which reduces usable space more than people expect.
Things that eat into usable area:
- Vents, chimneys, skylights and dormers
- Shade from trees, neighbouring buildings or a taller part of your own roof
- Multiple small roof faces that don't fit full rows of panels
If your roof won't fit the system you want, higher-wattage panels can help a little. A ground mount is another option if you have the land.
Step 5: Decide what percentage to cover
Covering 100% of your annual use isn't always the goal. Here's how your local rules should steer you:
- Full retail net metering with a yearly bank: sizing close to 100% of annual use usually makes sense. Avoid oversizing, because surplus is often forfeited.
- Lower export credits or net billing: each exported kWh is worth less than one you use. Many owners size to cover daytime and seasonal use, perhaps 50–80% of annual consumption.
- No-export or rebate-linked conditions: in some programs, like Ontario rebates that bar net metering, sizing to what you use in real time, or adding a battery, matters most.
Our net metering guide explains your province's rules. Our payback guide shows how sizing affects returns.
Plan for future electricity use
A home's electricity use often rises when it electrifies. If you're planning a heat pump or an EV in the next few years, consider:
- Sizing up now if your roof and rules allow it. Adding panels later costs more per watt.
- Choosing an inverter with headroom, or microinverters, which make expansion easier.
- Doing efficiency upgrades first. Air sealing and insulation shrink the load solar needs to cover. See our whole-home upgrade sequence.
An EV driven about 15,000 to 20,000 km a year might add roughly 2,500 to 4,000 kWh, depending on the vehicle and climate. Learn more in our EV section.
Frequently asked questions
How many solar panels does it take to power a house in Canada?
For a typical home using 7,000 to 11,000 kWh a year, often around 15 to 30 panels of 400–450 W each. Your location, roof orientation and shading can push that up or down.
Can I start small and add panels later?
Yes, but plan for it. Microinverter systems expand most easily. String systems may need a second inverter. Utility approvals, and in some provinces size rules tied to your past consumption, also apply to expansions.
Does panel efficiency change how many I need?
Higher-efficiency panels produce more per square metre, so you need fewer of them to reach the same system size. They don't change the total kilowatts you need, only how much roof it takes.
The bottom line
Sizing solar comes down to three numbers: your annual kWh, your local yield per kilowatt, and your panel wattage. Run the simple math, check it against your roof space, then adjust for your utility's export rules and any electrification plans. Use your estimate to sanity-check installer proposals. If a quote is far larger or smaller than your math suggests, ask why. Start with our solar overview and the glossary for any unfamiliar terms.
Sundamentals is an independent, non-profit education platform. Program details and prices change often — check current programs for your address in our rebate finder.