Solar Panel Output Calculator (Canada)

How to use this calculator

Enter six numbers and the calculator returns daily, monthly, annual, and 25-year energy output, plus dollar savings:

1. Array size (W) — total panel wattage. A 7.5 kW system is 7,500 W (popular Canadian residential size).
2. Peak sun hours per day — see provincial averages above. Default 3.8 is a Canada-wide populated mean.
3. System efficiency (%) — 76% accounts for higher snow and winter losses. Pure summer-only operation can hit 80%.
4. Panel age (years) — 0 for new install.
5. Electricity rate (C$/kWh) — provincial averages: Quebec 8 c, Manitoba 10 c, Ontario 14 c (TOU), BC 11 c, Alberta 18 c (Default), Atlantic 16–18 c.
6. Annual rate escalation (%) — Canadian retail electricity has risen 2–3%/yr historically. 2.5% is a balanced default.

The formula

daily_kWh    = array_W × peak_sun_hours × derate / 1000
annual_kWh   = daily_kWh × 365
lifetime_kWh = sum over 25 years of annual_kWh × (1 - degradation)^year

A worked example for a 7.5 kW system in Calgary:

• 7,500 W × 4.3 sun-hr × 0.76 = 24.5 kWh per day
• 24.5 × 30.4 = 745 kWh per month
• 24.5 × 365 = 8,953 kWh per year
• At C$0.18/kWh Alberta default rate: C$1,612 in year-1 bill savings
• Lifetime (25 years, 0.5% degradation, 2.5% escalation): about C$53,000 in savings

Output reference table by system size

Using 3.8 peak sun hours, 76% derate, 0-year age, C$0.16/kWh, and 2.5% annual rate escalation:

A 15 kW system at 3.8 PSH delivers comparable annual output to a 12 kW system in Phoenix — that’s the Canadian winter penalty.

What changes Canadian output

Province and latitude

Saskatchewan and southern Alberta are the Canadian solar sweet spot — clear skies, dry climate, and high irradiance. Ontario and Quebec are average. BC coast (Vancouver, Victoria) and the Atlantic provinces sit at the bottom because of cloud cover. NRCan PV Potential maps quantify this for any postal code.

Tilt — steeper than US

Canadian latitudes (45–55°N) call for steeper tilts than US installs. The tilt calculator shows latitude tilt is best for year-round, but 5–10° steeper than latitude maximises winter production and helps shed snow. Roof-pitched systems often live with 25–30°, which costs 4–6% versus optimal but is the practical reality for retrofit installs.

Snow

Snow blocks 100% of production until it slides off. Steeper tilts (40°+) and dark frame panels speed snow shedding. December and January production on a typical Ontario rooftop is 25–40% of the annual monthly average; June is 160–180%. Annual totals account for this — don’t size based on summer production.

Cold temperature gain

Cold panels actually produce slightly more than rated. -10°C cell temperature on a sunny February day gives 110–112% of nameplate. This partly offsets the short-day penalty. Canadian PSH calculations from NRCan already include this gain.

Snow albedo

Fresh snow on the ground reflects 70–80% of incident sunlight back at panels. A bifacial array (50–55% bifaciality) gains 5–10% annual production from snow albedo in northern installations. Worth the 5% panel premium if you have a ground-mount or open ballasted roof.

Why the 76% derate (not 78%)

Canadian residential systems run about 2 percentage points below US PVWatts default because:

• Snow losses: 1–3% annual on tilted arrays, more on lower-pitched roofs
• Inverter efficiency in cold: actually slightly higher than US summer baseline
• Soiling: 1.5% (less than US average due to more rain/snow rinsing)
• Wiring losses in cold: marginal benefit (lower copper resistance)

Net: 76% is the right default for Canadian residential. Bump to 79–80% for a southern BC install with no snow concern; drop to 73% for a flat Toronto rooftop with poor snow shedding.

Common Canadian mistakes

• Sizing for summer: A system that “covers” summer use will only produce 30–40% of need in December.
• Ignoring snow: A 30° pitch holds snow for days; 45°+ sheds quickly. Match panel tilt to your snow situation.
• Quoting from US sites: EnergySage, NREL PVWatts, and SEIA data is US-only. Canadian sizing must use NRCan/RETScreen.
• Forgetting CSA C22.1: All Canadian residential PV must comply with CSA C22.1 (Canadian Electrical Code). Inverters and isolators must carry CSA marks.

Sources

• NRCan Photovoltaic Potential and Solar Resource Maps — provincial output benchmarks
• CanmetENERGY RETScreen Expert — official Canadian sizing tool
• Canada Greener Homes Loan — federal financing program
• Solar Industry Magazine — Canada — install and incentive tracking
• HomeStars Solar Cost Reports — provincial install pricing