Why azimuth comes first
In the northern hemisphere the sun travels across the southern sky, so a roof face pointing due south generally collects the most energy across a full year. East- and west-facing faces collect less annually, but they shift production toward morning and afternoon respectively. A pure north-facing slope is the weakest option at Canadian latitudes and is usually avoided for the main array.
Many Canadian homes cannot offer a clean south face. In those cases an east-west split across two roof slopes is a common compromise: the annual total is lower than an unobstructed south roof, but the production curve is flatter and wider through the day, which can suit a household that uses power in both the morning and evening.
Tilt and latitude
Tilt is the angle between the panel and the horizontal. A widely used starting point is to set the tilt close to the site's latitude, which balances the high summer sun against the low winter sun. Canadian cities sit at relatively high latitudes, so latitude-matched tilts tend to be steeper than those used farther south.
Adjusting away from latitude shifts the seasonal emphasis:
- A shallower tilt favours the summer months, when the sun is high.
- A steeper tilt favours the lower winter sun and also helps snow slide off the glass.
How roof pitch interacts
On a roof-mounted residential system the panels usually follow the roof pitch rather than sit on adjustable racking, because flush mounting is simpler, more wind-resistant, and visually cleaner. That means the existing roof slope effectively chooses the tilt. The table below summarises the qualitative direction of each choice rather than precise figures, which depend on the specific location.
| Choice | Annual capture | Seasonal bias |
|---|---|---|
| South-facing, latitude tilt | Highest | Balanced |
| South-facing, steep tilt | Slightly lower | Favours winter; sheds snow |
| East & west split | Lower | Wider daily curve |
| North-facing | Lowest | Generally avoided |
Orientation and tilt set the ceiling for an installation. Shading from chimneys, vents, and neighbouring trees can reduce real output well below that ceiling, so a site assessment matters as much as the geometry.
Shading and obstructions
Even a partly shaded panel can drag down the output of others wired with it, depending on the system layout. Common residential obstructions include plumbing vents, chimneys, satellite dishes, and seasonal tree cover. A shade study across the day and across seasons gives a more honest picture than a single midday glance.
Practical takeaways
- Treat a clear south roof face as the strongest default, then consider east-west splits where it is unavailable.
- Expect Canadian latitude-matched tilts to be on the steeper side.
- Remember that a steeper tilt both favours winter sun and encourages snow to shed.
- Account for shading before assuming any orientation will reach its theoretical ceiling.
For background on how snow accumulation interacts with these geometry choices, continue with the snow-load and winter-yield guides below. General resources on solar geometry are available from public bodies such as Natural Resources Canada and the U.S. National Renewable Energy Laboratory.