Francis Knows: kWh/kWp
KWh/kWp is commonly used as a metric to evaluate the overall site and design efficiency of your proposed system, and illustrates the amount of kilowatt-hours one kilowatt of installed solar will produce in one year, and is specific to your site.
Solar installations produce a varied amount of energy throughout the day, as well as each month and each year. This variance is caused by weather, temperature, the age of the solar modules, and the collection of dirt and pollen on the surface of the modules.
From system to system, the amount of energy produced in one year is determined primarily by the angle of the modules away from horizontal and the azimuth, or compass direction, of the system. Additionally, the components selected and electrical code compliance of the installation can affect this output.
It is very common to see 1,200 kWh per kW of panels installed in low-sun areas, near 1,500 in many US areas, and up to 1,800-2,000 or more for tracking systems or very sunny areas of the country.