Solar in Canadian winters

It is reasonable to wonder whether solar makes sense in a country known for long winters. The short answer is that winter production is low, but it is a small part of the year, and the rest of the year does the heavy lifting. Here is what actually happens.

Cold helps, darkness hurts

Solar panels are electronic devices, and like most electronics they work more efficiently when they are cool. On a bright, cold day, a panel can produce more power than it would on an equally bright hot day.

The real winter challenge is not temperature. It is daylight. Days are short, the sun sits low in the sky, and its light passes through more atmosphere before it reaches your roof. That combination means far less energy reaches the panels.

What about snow

Snow does cover panels, and a covered panel produces little or nothing. But several things work in your favour:

• Panels are smooth glass, and most are installed at an angle. Snow tends to slide off, often within a day or two of a storm.
• Panels are dark and absorb some heat from sunlight, which helps loosen snow from the bottom edge.
• Snow on the ground can reflect extra light onto clear panels.

Clearing panels yourself is generally not recommended. Climbing on a snowy roof is dangerous, and scraping can damage the glass or void a warranty. In most cases it is best to let the snow clear on its own.

Flat or low-pitch systems hold snow longer, which is something to factor in for those roofs.

How much does winter matter

In southern Canada, the darkest winter months produce only a small fraction of a system's annual energy. Most production comes from late spring through early autumn, when days are long and the sun is high.

This is why solar should always be judged on annual production and savings, not on a single month. A system that produces very little in December may still produce a large share of your yearly use overall.

Why net metering banking matters

Your home tends to use more electricity in winter, especially if you heat with electricity or run lights for longer evenings. Your panels produce more in summer. The two are out of sync.

Net metering bridges that gap. Summer surplus becomes bill credits, and in Ontario those credits can roll over for up to 12 months. The credits you build in June can help offset bills in January.

Without net metering, such as on a system that takes Ontario's HRSP rebate, summer surplus has much less value. That system should be sized more closely to what you use at the time. See net metering vs the rebate for how to choose.

Comparing with other northern countries

Solar is widely used in countries with high latitudes and grey winters. Germany, for example, has a large amount of rooftop solar even though Berlin sits further north than Toronto, Montreal or Vancouver. Latitude alone does not rule solar out.

What matters more for a Canadian home is local sunlight, roof direction, shading, electricity prices and how exported power is credited.

Practical winter tips

• Expect your monitoring app to show very low numbers on short, overcast or snowy days. That is normal.
• Don't climb on the roof to clear snow. If you are concerned, ask your installer about safe options.
• Check that snow sliding off panels won't land on a walkway, entrance or driveway. Snow guards can help in some cases.
• Look at production over a full year, not one month, before deciding whether the system is performing as expected.

When winter really is a problem

Some homes are poor fits regardless of season. A roof that faces north, sits under tall evergreens, or is shaded by a neighbouring building may lose so much winter and shoulder-season sun that the numbers don't work. We will tell you if that is the case for your roof. Learn more in is my roof suitable.

Next step

See your estimated production across the year: check your roof.