How Many Solar Panels Do I Need?
Free Canadian solar sizing calculator. Uses NRCan irradiance data, average household consumption (11,000 kWh/yr), and 400 W panel specs for accurate provincial estimates.
How Many Solar Panels Do I Need?
How to use this calculator
Enter five figures and the tool returns the system size in kW, panel count, required roof area, and estimated annual production:
- Monthly electricity use (kWh) — average from 12 months of bills. Statistics Canada 2026 puts the residential average at 920 kWh/month, but provinces with electric heat (QC, MB, BC) average 1,200–1,500 kWh/month.
- Peak sun hours per day — NRCan publishes 30-year mean values for any postal code. Continental Canada averages 3.0 (Vancouver) to 4.6 (Regina).
- Panel wattage (W) — 400 W is standard for residential CSA-certified panels in 2026 (Canadian Solar, Silfab, REC).
- System efficiency (%) — use 76% for typical Canadian installs. The 2-point reduction versus the US default reflects snow losses and longer winter inverter idle time.
- Offset target (%) — most provinces offer net metering at retail rates, so 100% offset is the standard target. Saskatchewan and BC are exceptions where time-shifted credits favour battery pairing.
The formula
required_kW = (annual_kWh × offset / 100) ÷ (peak_sun_hours × 365 × derate)
panel_count = ceil(required_W ÷ panel_wattage)
roof_area_m² = panel_count × panel_area × 1.08 (mounting clearance)Worked example for a Calgary home:
- Monthly use: 850 kWh → annual 10,200 kWh
- Peak sun hours: 4.5 (NRCan Calgary 30-year mean)
- Derate: 76%
- Required: 10,200 ÷ (4.5 × 365 × 0.76) = 8.17 kW
- At 400 W per panel: ceil(8,170 ÷ 400) = 21 panels
- Roof area: 21 × 2.1 m² = 44 m²
- Annual production: 8.4 kW × 4.5 × 365 × 0.76 = 10,489 kWh
Reference table by Canadian city
Using 76% derate, 400 W panels, 100% offset, household 920 kWh/month:
| City | PSH | System size | Panels | Roof area |
|---|---|---|---|---|
| Vancouver | 3.0 | 13.3 kW | 34 | 71 m² |
| Edmonton | 4.2 | 9.5 kW | 24 | 50 m² |
| Calgary | 4.5 | 8.8 kW | 22 | 46 m² |
| Regina | 4.6 | 8.6 kW | 22 | 46 m² |
| Winnipeg | 4.3 | 9.3 kW | 24 | 50 m² |
| Toronto | 3.8 | 10.4 kW | 26 | 55 m² |
| Ottawa | 3.9 | 10.2 kW | 26 | 55 m² |
| Montreal | 3.7 | 10.7 kW | 27 | 57 m² |
| Halifax | 3.6 | 11.0 kW | 28 | 59 m² |
Vancouver looks oversized, but its mild winters and lower BC Hydro rates mean residents typically install smaller systems and accept partial offset rather than fitting 34 panels.
What changes the panel count
Provincial irradiance and tilt
CSA C22.1 doesn’t dictate tilt, but NRCan recommends latitude tilt for year-round optimisation. Most Canadian sites benefit from a slightly steeper tilt (latitude + 5°) to favour spring/fall production over summer surplus. The solar panel tilt calculator computes the optimum for your latitude.
Net metering rules by province
- Ontario, Alberta, BC, NS, NB, PEI: 1:1 retail-rate net metering, annual true-up
- Quebec: 1:1 with Hydro-Québec, monthly carry-forward
- Saskatchewan: production credited at SaskPower’s avoided-cost rate (~7¢/kWh) — much lower than the 17¢/kWh import rate
- Manitoba: 1:1 retail rate
In provinces with poor net metering economics (SK, parts of BC), undersize the array to match daytime self-consumption rather than annual offset.
Cold-climate inverter behaviour
Modern transformerless inverters (Enphase IQ8, SolarEdge HD-Wave) operate down to -25°C without de-rating. Older central inverters in Quebec and Manitoba installs may shut off below -10°C for several morning hours, costing 1–2% annual production. CSA C22.1 plus CSA C22.2 No. 257 require all inverters to be tested for the climate zone they’re installed in.
Roof loading and snow
CSA SS6/CSA O86 timber-frame roofs handle solar dead loads (12–15 kg/m²) without alteration in zones 1–3. Heavy-snow zones (Quebec, northern Ontario, BC interior) need additional snow-load review per NBC Part 4. The solar panel roof load calculator walks through this.
Common Canadian mistakes
- Underestimating winter consumption. Electric-heat homes consume 2× the summer load in January. Always pull 12-month bill averages, not summer-only.
- Ignoring panel-temperature gain in summer. Even Calgary hits 30°C+ in July, and panel cell temperatures reach 60°C, knocking 12–14% off rated output.
- Skipping CSA-certified panels. ESA (Ontario) and provincial inspectors require CSA-certified equipment. Imported panels without CSA marks won’t pass inspection.
- Assuming Greener Homes Grant is still open. It closed February 2024. Federal incentives now flow through the interest-free Greener Homes Loan and provincial programs.
How this differs from an installer’s quote
NRCan-trained installers (look for CanmetENERGY-listed designers) use PVsyst or Helioscope tied to your exact site, with 30-year TMY3 irradiance and shading from LiDAR. This calculator uses provincial averages and CSA standard losses, so expect ±10% variance versus a real quote. Use it for budgeting and roof-fit verification before booking installer assessments via HomeStars.
Sources
- NRCan PVPMC Photovoltaic Potential Maps — irradiance by postal code
- CanmetENERGY Renewable Energy Resources — solar resource assessment
- Statistics Canada Residential Energy Consumption 2026 — provincial household kWh
- Canadian Solar Industries Association CanSIA — installed capacity and panel-mix data
- HomeStars 2026 Solar Cost Survey — provincial pricing benchmarks
- CSA C22.1 Canadian Electrical Code — installation standards