Shows Average Daily Sunlight Hours Available For Solar Electric (Solar PV) Panels

solar insolation chart shows average USA sunlight conditions
This solar sunlight availability chart shows the average hours of DNI (Direct Normal Irradiance). Of course diffuse, reflected and refracted light as well as high-angle-of-incidence radiation can still be collected. To estimate the net daily production of a stationary solar panel facing south and elevated to an angle to match the latitude, a good rule of thumb is to simply multiply the peak watts (as stated on the solar panels UL Listing) by the above DNI values for your area. This calculation will provide a conservative estimate of the average net daily production of a solar panel. Indirect insolation and high angle insolation (early morning and late afternoon) is disregarded in this simple calculation so as to offset average power losses due to wiring resistance, battery or inverter loss etc.

As an example, a 225 watt solar panel in Baltimore MD could be expected to produce approximately 1kWh (one kilowatt hour or 1000 watt hours) of net average power per day.
(225 x 4.5= 1012.5)

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