How much energy your system can generate depends on a number of factors.
Configuration
A solar PV system can either be affixed to your rooftop or to the ground (e.g., in your backyard). A professional installer can provide advice on the optimal location and configuration of the system on your property.
Orientation
The optimal orientation of rooftop solar panels in Canada is south-facing, but east- and west-facing orientations can provide around 70% of the output of a south-facing solar PV system.
Obstructions
Your installer will assess your roof and/or yard size and survey the area for any obstructions, both current and future. A professional assessment, including the measuring of solar irradiance (how much sunlight falls on your roof or yard) is required to estimate your potential system production. If you intend for your solar panels to be installed on your rooftop, you will typically need at least 3.7 m (12’) x 3.0 m (10’) of unobstructed area (clear of chimneys, roof vents, skylights, gables and other protrusions).
Roof condition
If you intend to install panels on your rooftop, the roof covering (e.g., shingles) should be less than 10 years old, so that the solar PV system can remain in place for the duration of its warrantied life (e.g., 25 years). Since 2012, the standard for “solar-ready” roof construction in Canada has been a load limit of 5 lbs per square foot from the solar panels, racking and other equipment. A qualified solar installer will determine compliance.
Calculating potential output
As the weather is not always consistent from year to year, production from your solar system can vary over time. Your installer should be able to offer some averaging factors for the fluctuation.
In addition, your solar system can produce power for well over 20 years, so you will need to account for any future obstructions: Is that sapling going to branch over your solar panels in a decade?
Your solar installer will assess your solar potential using tools and calculators that take into account all of these important variables. Some free tools are available to customers to perform a preliminary check for solar potential. Check back with us for links to tools here as more options become available.
Calculating your energy needs
Your electricity consumption may change over the years as well. Improving energy efficiency, purchasing an electric vehicle, using your AC system or your electric heating will increase your usage. These decisions may affect the overall size of your system.