Clear-Sky Insolation Model
This model provides one-minute insolation values for a specified location, date, and time. It uses the same model as
THIS WEB PAGE. A "pinched cosine" model can also be used
to replace minute-by-minute
calculations based on solar position with this calculation:
S=Ssolar noon•cos((tsolar noon - t)/thalf day•π/2)β
The example shown is for Ssolar noon = 1000 W/m2, thalf day = 500 min, tsolar noon = 740 min,
β = 1.3. An unmodified cosine model gives values that are too high during mid-morning and mid-afternoon.
The exponent β is chosen to provide the best fit for a particular site. It may depend on
latitude and time of year. For more information about using this model, contact David Brooks.
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