sun above water body demonstrating peak sun hours

What are the Average Peak Sun Hours in Ontario?

Average Peak Sun Hours (APSH) is an essential metric for anyone planning to install a solar power system. This guide will delve into the intricacies of APSH in Ontario, providing you with an in-depth understanding of this crucial concept. On average, Ontario has between 3 and 4.5 peak sun hours per day. However, to unlock the full potential of your solar power system, it’s crucial to understand the concept of peak sun hours and how it impacts solar power generation in Ontario. Let’s get started.

What are Average Peak Sun Hours?

Average Peak Sun Hours (APSH) is the amount of solar insolation, also known as solar irradiance, a square meter of your solar array receives when the sun is at its highest point in the sky. APSH represents the time during which your solar system produces its maximum output. It’s a standard global measure to compare solar potential between different locations.

Importance of Average Peak Hours in Solar Power Systems

peak sun hours Ontario

When installing a solar power system, the power generated by your solar panels largely depends on the sunlight they receive. Peak sun hours, therefore, influence the productivity of your solar panels. By understanding your location’s APSH, you can estimate how much energy your solar panels will produce.

Average Peak Sun Hours in Ontario

In Ontario, the average peak sun hours vary across the province. Generally, Ontario averages between 3 and 4.5 peak sun hours per day, depending on the time of the year and geographical location. For more specific figures on total sun hours, you can consult a peak sun-hours map to represent your location’s solar potential accurately.

Ontario versus Other Canadian Cities

When comparing Ontario to other Canadian cities, the province generally has more average peak sun hours. For instance, cities in British Columbia usually receive fewer sun hours due to their climate and location. However, Ontario’s moderate sun is still less than in more southern regions.

How to Improve Your Solar System Efficiency in Ontario

Optimal Tilt Angle

The tilt angle of your PV panels significantly influences their efficiency. The optimal tilt angle in Ontario is approximately 45 degrees, but this can vary depending on the time of year.

Use of High-Efficiency Solar Panels

Given Ontario’s sun-hours variability, high-efficiency solar panels can maximize the amount of solar energy generated during peak sun hours.

Estimating Solar Power Output in Ontario

To estimate your solar power output in Ontario, consider the APSH, the power rating of your solar panels, and the area of your solar array. This calculation is critical to determining whether investing in a solar energy system will meet your energy needs.

Understanding Solar Insolation and Global Horizontal Irradiation

Critical terms like solar insolation (SI) and Global Horizontal Irradiation (GHI) are vital when planning a solar system. Again, that helps to maximize your solar panel’s solar potential and output.

Solar irradiance measures the concentration of solar energy in a specific area over a set time. It is generally in watts per square meter (W/m²). The amount of SI a place receives depends on several factors, including the time of year, weather conditions, and geographical position. In solar energy, SI often represents a peak sun hour. Also, this is the number of hours per day corresponding to a “peak sun hour,” defined as when solar irradiation averages 1,000 W/m2.

Global Horizontal Irradiation (GHI) is another critical metric in solar energy systems. GHI measures the total amount of shortwave radiation from above by a surface horizontal to the ground. This figure includes Direct Normal Irradiance (DNI) and Diffuse Horizontal Irradiance (DHI). It represents the sum of the sunlight directly reaching the ground (DNI) and the sunlight scattered by the atmosphere (DHI). GHI is especially pertinent for photovoltaic installations, including solar panels, as it estimates how much sunlight a solar panel can convert into electricity.

In essence, SI and GHI tell you the potential of a ‘full sun hour’ – a term used to describe an hour during which the intensity of sunlight is 1,000 watts per square meter. These metrics help determine how many hours of ‘full sun’ a solar system can expect at a particular location, guiding decisions about the optimal setup and positioning of solar panels to maximize energy production.

Daily Global Insolation in Ontario

Like other regions, Ontario’s daily global insolation depends on various factors. These include the time of year, cloud coverage, and the province’s exact location.

As the Earth orbits the sun, the angle at which sunlight hits different latitudes changes, resulting in seasonal variations in insolation. Therefore, in Ontario, the daily global insolation varies throughout the year. Ontario experiences about 3 to 4.5 kilowatt-hours of solar insolation per square meter daily. However, these figures can rise during the summer when the days are longer, and the sun is more directly overhead.

During summer, the province can enjoy up to 6 peak sun hours on a clear day. On the other hand, during winter, the peak sun hours can drop to as low as 2-3 hours due to shorter daylight hours and the sun’s lower angle.

These values are critical for planning a solar energy system in Ontario. With an understanding of daily global insolation and the average number of peak sun hours, solar system owners can size their systems correctly. Furthermore, this ensures the system produces sufficient power to meet its energy needs throughout the year, even when the peak sun hour rate is less.

Remember, the daily insolation is average, and real-world conditions can vary. Therefore, designing solar energy systems with a buffer is recommended, ensuring they can meet energy needs even on days with less than regular peak sun hours. In this way, Ontario’s residents can make the most out of their solar systems, maximizing their energy production and reducing their reliance on the grid.


Understanding the average peak sun hours is crucial when planning a solar power system in Ontario. It directly influences the amount of solar power generated and, therefore, the efficiency of your solar system. By understanding the solar potential of your specific location and adjusting factors like tilt angle and solar array size, you can maximize the benefits of your solar power system in Ontario. This guide provides the comprehensive information you need to make informed decisions about your solar energy initiatives in Ontario.





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