Your best guess is good enough to get started. Location quality is determined by the direction your roof faces and the amount of shading on your roof. South-facing roofs with absolutely no shading are ideal.
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What is Site Quality
What is Site Quality?
Site quality is a number that converts the amount of solar panels you install on your roof to the amount of electricity your panels will produce. A 1200 site quality means 1,000 watts of installed solar panels will produce 1,200 kilowatt-hours of electricity over the course of a year.