Three Panel Technologies in Common Use

Residential solar installations in Canada currently rely on three photovoltaic panel technologies: monocrystalline silicon, polycrystalline silicon, and thin-film. Each technology involves a different manufacturing process, which affects its cost, physical footprint, and behaviour under the irradiance and temperature conditions typical of Canadian climates.

The choice between them depends on available roof area, shading patterns, household electricity demand, and budget. There is no universal best option; the right type depends on the specific installation context.

Monocrystalline Silicon Panels

Monocrystalline panels are cut from a single continuous silicon crystal grown through the Czochralski process. The resulting cells are uniformly dark in appearance and achieve laboratory conversion efficiencies above 26% for the best research cells, with commercial residential modules typically rated between 18% and 23% under standard test conditions (STC).

For Canadian homeowners with limited south-facing roof area, monocrystalline panels generate more electricity per square metre than the alternatives. This density advantage is meaningful in urban neighbourhoods where roofs may be partially shaded or fragmented by dormers, skylights, and mechanical vents.

Temperature Behaviour in Cold Climates

All silicon panels produce more power in cold conditions than in heat. A typical monocrystalline panel carries a temperature coefficient of approximately −0.36% per degree Celsius above the STC reference of 25 °C. Canadian winters keep panel temperatures well below 25 °C for months at a time, meaning actual output can exceed the STC rating during cold sunny days in January or February — a counterintuitive benefit of northern installations.

Snow accumulation is the offsetting factor. Panels mounted at shallow angles may retain snow longer than steeply pitched ones. The surface coating of most commercial panels is smooth enough to shed snow gradually, but sustained heavy snowfall can reduce output to zero for days at a time in regions such as Montréal, Ottawa, or Edmonton.

Note on STC vs. PTC ratings: Standard Test Conditions (STC — 1,000 W/m², 25 °C, 1.5 air mass) do not reflect real operating temperatures. The PTC (PVUSA Test Conditions — 1,000 W/m², 20 °C ambient, 1 m/s wind) rating is closer to outdoor performance and is the figure used in California Energy Commission listings, which many Canadian installers reference.

Polycrystalline Silicon Panels

Polycrystalline panels are produced by pouring molten silicon into square moulds and allowing it to cool. The resulting ingot contains multiple crystal grains, giving the cells a characteristic blue-speckled appearance. The manufacturing process is less energy-intensive than growing a single crystal, which historically translated into lower module prices.

Efficiency ratings for polycrystalline modules in the residential market typically fall between 15% and 18%, requiring larger roof area for the same output as an equivalent monocrystalline system. On large, unobstructed south-facing roofs — common in suburban Ontario, Alberta, or Saskatchewan — the lower cost per watt of polycrystalline panels can make them financially attractive.

Market Context

By the mid-2020s, the price gap between monocrystalline and polycrystalline modules narrowed significantly as manufacturing scale increased for both types. Many installers moved toward monocrystalline as the default option even in cost-sensitive projects, reflecting improved manufacturing economics rather than any fundamental change in polycrystalline performance.

Thin-Film Panels

Thin-film photovoltaics deposit one or more layers of semiconductor material — commonly cadmium telluride (CdTe), copper indium gallium selenide (CIGS), or amorphous silicon (a-Si) — onto a glass, metal, or plastic substrate. The resulting panels are lighter and more flexible than silicon wafer modules.

Conversion efficiencies for commercially available thin-film residential panels generally range from 10% to 14%, lower than crystalline silicon. This means a thin-film installation of equal output requires notably more roof area. However, thin-film panels degrade less sharply under partial shading and maintain proportionally higher output under diffuse light conditions — a relevant consideration for British Columbia's overcast coast or the Atlantic provinces where cloud cover is frequent.

Durability Considerations

Some thin-film formulations — particularly older amorphous silicon products — have historically shown faster degradation rates than crystalline silicon under sustained UV exposure. CdTe and CIGS modules have improved significantly; commercial manufacturers of CdTe products publish 25-year linear power warranties comparable to crystalline silicon.

Side-by-Side Comparison

Characteristic Monocrystalline Polycrystalline Thin-Film
Typical module efficiency 18–23% 15–18% 10–14%
Roof area for 5 kW system ~25–30 m² ~30–35 m² ~40–50 m²
Relative upfront cost (per W) Moderate–High Moderate Low–Moderate
Performance under partial shade Poor–Moderate Moderate Good
Cold-climate temperature benefit High High Moderate
Typical warranty period 25–30 years 25 years 25 years (CdTe)

Bifacial Panels

A growing category of monocrystalline modules captures light from both the front and rear surfaces. Ground-mounted or racking-elevated roof installations can see production gains of 5–20% from reflected light reaching the rear surface, depending on the albedo of surrounding surfaces. Snow-covered rooflines and light-coloured membrane roofing can enhance rear-side irradiance during winter months.

For standard flush roof mounts with limited clearance between panel and roofing material, bifacial gains are minimal and the premium cost of bifacial modules may not be justified.

Inverter Compatibility

Panel type affects inverter selection. String inverters — the most common configuration in residential systems — perform best when all panels in a string share the same orientation and face uniform irradiance. On roofs with multiple faces or intermittent shading, microinverters or DC power optimisers allow each panel to operate at its individual maximum power point. The additional cost of microinverters is sometimes offset by higher annual energy harvest on complex roof geometries.

External References

Panel specifications and efficiency ratings are published by manufacturers and independently tested by organisations including:

General reference information only. Panel specifications change as manufacturers update product lines. Verify current specifications directly with manufacturers or distributors before making purchasing decisions. This content does not constitute engineering advice.