Solar works well in cold climates, better than many people assume. Germany, the Nordics and the northern US have substantial installed capacity operating successfully. But several design factors differ from temperate practice.
Modules perform better at low temperature. With a typical coefficient around -0.35%/°C, a module at -5°C produces roughly 10% more than the same module at 25°C for equal irradiance.
Clear cold days therefore produce excellent specific output, and snow on the ground raises albedo substantially, which lifts both diffuse irradiance and bifacial rear-side gain. Some northern installations record their best instantaneous output on bright winter days.
The design point most often missed. Module open-circuit voltage rises as temperature falls. String voltage must stay below the inverter's maximum DC input at the lowest expected module temperature, not at standard conditions.
String length must be calculated against the record low ambient for the site, with margin. Exceeding inverter maximum voltage on a cold clear morning damages equipment and voids warranty, and it happens on systems designed with temperate assumptions.
Practically, this means shorter strings in cold climates than the same equipment would allow elsewhere – a real design constraint with cost implications.
Snow blocks light entirely. Annual production losses from snow cover vary widely – from around 1-3% in regions with occasional light snow to 10% or more where cover persists.
What drives shedding:
The tension for commercial flat roofs: low tilt reduces wind load and row spacing, which is why it is chosen – and it is exactly what impedes snow shedding. In snowy regions that trade-off deserves explicit consideration rather than defaulting to the low-tilt standard.
Snow sliding off an array has to land somewhere. On a roof, that means accumulation at the base of each row, and potentially against parapets or plant. On carports and ground mounts, it means a shedding zone that must not be a walkway, doorway or parking bay.
Snow guards and barriers exist but add cost and can themselves cause accumulation. Better to design the layout so shed snow lands harmlessly.
Covered elsewhere but critical here: the combination of array dead load, snow load and drift accumulation around rows governs the structural assessment. Rows of modules act as obstructions that create drifts substantially deeper than uniform ground snow.
Both ASCE 7 and EN 1991-1-3 address drifting, and applying them properly to an array layout requires deliberate analysis. A uniform snow load check across the roof is not sufficient.
Usually not. The economics rarely justify it: winter irradiance is low, so the recovered energy is modest, while access is hazardous and the risk of damaging modules is real.
Hard tools scratch glass, and walking on snow-covered modules is both dangerous and damaging. Where clearing is genuinely warranted – long-persisting cover in a high-value application – use purpose-made soft roller tools from the ground, and accept leaving a thin layer rather than scraping to the glass.
For most commercial installations, letting it shed naturally and accepting the modelled loss is the correct answer, provided the loss was modelled honestly in the first place.