Part 1: Cold Weather Advantage
Why Your Panels Love an Ontario Winter
As a solar installer, the first question we get when the temperature drops is always the same: “Do solar panels even work in an Ontario winter?”
It’s a fair question. We’ve all seen a roof blanketed in snow and thought, “Well, that’s that for a few months.”
This is the biggest myth in the solar industry, and we’re here to bust it.
Not only is the idea that “solar panels don’t work in winter” false, but the truth is, in some ways, solar panels work even better in the cold.
The “Light vs. Heat” Misconception
The core of the myth comes from a simple misunderstanding. We associate the sun with heat, so we assume solar panels need heat to work.
They don’t.
Solar panels are photovoltaic (PV), which means they convert light (photons) directly into electricity, not heat. In fact, solar thermal panels do exist (they’re often used for heating pools), but they are a completely different technology.
For your home’s photovoltaic panels, heat is not just unnecessary—it’s the enemy.
Electronics Like to Be Cool
Think of your solar panels as a piece of electronics, just like your laptop or smartphone. What happens when your laptop overheats? It slows down, becomes less efficient, and may even shut off.
Solar panels are the same. They are tested and rated at a standard temperature of 25°C (77°F). For every degree above this, a panel’s efficiency actually drops. On a scorching +35°C July day in Toronto, your panels are losing power.
Conversely, for every degree below 25°C, a panel’s voltage and efficiency increase.
This means that a crisp, clear, -10°C January day is the perfect operating environment for your panels. The cold air allows them to convert light into electricity at their peak efficiency, generating more power per hour of sunlight than they can on a sweltering summer day.
The Winter “Bonus”: The Albedo Effect
Winter gives us another surprising advantage. When the ground is covered in a blanket of white snow, it acts like a giant mirror.
This is called the “Albedo Effect”.
Fresh snow reflects 80-90% of the sunlight that hits it. This reflected light bounces back up onto your panels, giving them a “bonus” dose of sunlight from the ground. A 2024 University of Ottawa study confirmed that this reflective boost can increase a panel’s energy output.
The Takeaway: Scientifically, cold is good for solar panels. But this leads to the next logical question: “If the science is so good, what about the very visible problem of snow covering the panels and the short, dark days?”
We’ll tackle that in Part 2.
