Example with 400W panels, 4h sun: 37.5 ÷ (400 × 4 ÷ 1,000) = 37.5 ÷ 1.6 = 24 panels
📊 Calculation Standards:
Peak sun hours sourced from Natural Resources Canada (NRCan) solar radiation data. System loss default of 20% follows CEC 2024 guidelines, accounting for inverter efficiency, wiring losses, soiling, and temperature derating. Last updated: February 2026.
Peak Sun Hours by Province
Peak sun hours represent the number of hours per day when solar irradiance averages 1,000 W/m² — the standard used to rate solar panel output.
Province / Territory
Avg Peak Sun Hours/Day
Best Region
Notes
Alberta (AB)
4.5–5.0h
Southern AB
Canada's sunniest province
Saskatchewan (SK)
4.2–4.8h
South SK
Excellent solar resource
Manitoba (MB)
3.8–4.2h
Southern MB
Good solar potential
Ontario (ON)
3.7–4.3h
SW Ontario
Windsor area gets the most
British Columbia (BC)
3.5–4.8h
Okanagan, Interior
Coastal BC much lower than interior
Quebec (QC)
3.5–4.1h
South QC
Strong summer solar, lower in winter
Nova Scotia (NS)
3.3–3.8h
South Shore
Viable but lower yields
New Brunswick (NB)
3.2–3.7h
South NB
Similar to NS
PEI
3.3–3.7h
—
Relatively consistent
Newfoundland (NL)
2.8–3.5h
Avalon Peninsula
Lower yields, still viable
Frequently Asked Questions
How many solar panels do I need for a 1,000 kWh/month home?
A home using 1,000 kWh/month needs roughly 26–30 standard 400W panels in most Canadian locations (assuming 4 peak sun hours/day and 20% system losses). In Alberta with 4.8 peak sun hours, you'd need closer to 22–24 panels. In Nova Scotia at 3.5 hours, you'd need 30–34 panels for the same usage.
What is a "peak sun hour" and why does it matter?
A peak sun hour is one hour of sunlight at 1,000 W/m² intensity — the standard used to rate solar panels. A 400W panel produces 400 Wh (0.4 kWh) in one peak sun hour. If your location gets 4 peak sun hours per day, one 400W panel produces 1.6 kWh/day. More peak sun hours = fewer panels needed for the same output.
What size solar panels should I choose?
For residential rooftop systems: 370W–420W monocrystalline panels offer the best balance of efficiency and cost. For off-grid cabins or limited roof space: 200W–300W panels are common and easier to handle. Larger wattage panels mean fewer panels needed but cost more per unit — the total system cost per watt is usually similar regardless of panel size.
How much roof space will I need?
A standard 400W panel is roughly 1.7m × 1.0m (about 1.7 m² or 18 sq ft). For a typical 24-panel system you'd need about 40 m² (430 sq ft) of south-facing roof space. Add 20–30% extra space for mounting gaps and maintenance access. East or west-facing roofs reduce output by 15–20% compared to south-facing.
Should I oversize my solar array?
Yes — sizing to 110–125% of your calculated need is common practice. This accounts for panel degradation (~0.5% per year), cloudy days, winter production drops, and any future increase in your electricity usage. In Canada especially, winter sun hours can be 40–60% lower than summer, so sizing for annual average means winter shortfalls.
Does this include battery storage?
No — this calculator sizes your solar panel array only. Battery storage is calculated separately based on how many days of autonomy you want. Use our battery runtime calculator to size your battery bank once you know your daily energy needs.