Choosing Solar Panels for Your Home

The solar panel market offers several distinct technologies, each with different efficiency levels, physical characteristics, and performance trade-offs. For a residential installation in Canada, the choice of panel type affects how much electricity the system produces, how much roof space it requires, and how it performs under specific local conditions.

Panel Technologies

Monocrystalline Silicon Panels

Monocrystalline panels are manufactured from a single continuous crystal of silicon. This structure allows electrons to move more freely, resulting in higher efficiency — typically in the range of 19% to 23% for current residential-grade panels, with some premium models exceeding this range. Their higher efficiency means more power output per square metre of panel area.

For Canadian rooftops where available area may be limited — particularly on bungalows, townhouses, or homes with complex roof shapes — monocrystalline panels allow a larger system to fit in a constrained space. They are also generally better at performing in low-light and diffuse light conditions compared to polycrystalline panels, which is relevant for overcast days and winter months.

Monocrystalline panels are generally more expensive per panel than polycrystalline equivalents, though the cost gap has narrowed substantially in recent years.

Polycrystalline Silicon Panels

Polycrystalline panels are made by melting multiple silicon fragments together. The resulting crystal structure is less uniform, which limits electron movement and produces slightly lower efficiency — typically 15% to 18%. This means more panel area is needed to achieve the same output as a monocrystalline array.

They tend to be less expensive per panel and are a viable choice where available roof area is not a limiting factor. Performance in high heat is modestly better than monocrystalline panels in some cases, though this advantage is less relevant in Canadian climates where extreme heat is limited.

Thin-Film Panels

Thin-film technology deposits semiconductor material in a thin layer on a substrate such as glass or flexible backing. Common variants include amorphous silicon (a-Si), cadmium telluride (CdTe), and copper indium gallium selenide (CIGS). Efficiency is generally lower than crystalline silicon panels, typically in the 10% to 16% range, requiring considerably more area for equivalent output.

Thin-film panels are less commonly used in residential rooftop applications in Canada due to space requirements and cost per watt at smaller scales. They are more prevalent in commercial and utility-scale applications where space is less constrained.

Rated Power Output

Panels are rated by their power output in watts under standard test conditions (STC) — a controlled measurement at 25°C and 1000 W/m² irradiance. Current residential panels typically range from approximately 350 W to 500 W per panel. Higher-wattage panels produce more electricity per unit but are physically larger.

The total system capacity (in kilowatts) is the sum of all panel ratings. A common residential installation in Canada ranges from roughly 5 kW to 15 kW depending on household consumption, available roof area, and budget.

Temperature Coefficient

As noted in relation to Canadian climate conditions, the temperature coefficient describes how much a panel's output changes with temperature. A lower negative coefficient (e.g., −0.25% per °C) means the panel retains more of its output at elevated temperatures. In Canadian climates, the benefit of cold-weather performance enhancement is equally important: on a cold clear day, panels produce above their rated output.

Durability and Load Ratings

Canadian winters impose mechanical loads from snow and ice on rooftop panels. Panels are certified to specific load ratings measured in Pascals (Pa). Standard panels typically carry ratings sufficient for normal residential snow loads, but homes in areas with heavy or wet snowfall should confirm the specific panel's load certification with the installer.

Hail resistance ratings indicate the diameter of hailstone the panel glass is certified to withstand without damage. Most standard residential panels meet IEC 61215 certification requirements, which include a hail impact test.

Warranties

Two warranty types apply to solar panels:

• Product warranty: Covers manufacturing defects. Typically 10 to 15 years for standard residential panels, longer for premium products.
• Performance warranty: Guarantees a minimum power output over time. Typically guarantees at least 80% of rated output after 25 years, with some manufacturers guaranteeing 90% after that period.

The value of a warranty depends on the manufacturer's financial stability and ability to honour it over a 25-year period. Established manufacturers with documented track records are generally preferred for long-term warranty reliability.

Certifications

For residential use in Canada, panels should carry relevant certifications including IEC 61215 (design qualification for crystalline silicon panels), IEC 61730 (safety qualification), and UL or CSA certification as required by local electrical codes. These certifications confirm that the product has been independently tested to established standards.

Roof Considerations

Panel selection also interacts with roof characteristics. Heavier panels require adequate structural support. The roof pitch affects snow shedding and the effective irradiance angle. On complex roofs with multiple sections, micro-inverters or power optimizers may be specified to allow each panel to operate independently, reducing the impact of partial shading on overall system output.