Simple Solar Spectral Model for Direct and Diffuse Irradiance on Horizontal and Tilted Planes at the Earth's Surface for Cloudless Atmospheres

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To present a new, simple model for direct and diffuse spectral irradiance on horizontal and tilted surfaces at the earth's surface for clear days.


In a previous report (SERI/TR-215-1781), we described a simple model for calculating direct normal and diffuse horizontal spectral irradiance for clear days. In this report, we present a new, simple model that incorporates improvements to the simple model approach and an algorithm for calculating spectral irradiance on tilted surfaces. The goal is to provide researchers with the capability to calculate spectral irradiance for different atmospheric conditions and different collector configurations/orientations using microcomputers.


A new, simple, spectral irradiance model has been formulated that produces terrestrial spectra between 0.3 and 4.0 Ám with a resolution of approximately 10 nm. Inputs to the model include the solar zenith angle, the collector tilt angle, atmospheric turbidity, the amount of precipitable water vapor and ozone, surface pressure, and ground albedo.

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