NREL: MIDC Solar Position Calculators

SOLAR POSITION CALCULATORS

NREL's Measurement & Instrumentation Data Center provides web based applications for calculating solar position and/or intesity. Please remember that the amount of solar energy received by the Earth is highly variable both in time and space (from location to location), and that these mathematical models cannot be expected to produce an exact replication of any given set of physical conditions.

SOLPOS: SOLPOS calculates the location of the sun in the sky and its intensity for any given location, day, and time. Valid from the year 1950 to 2050 CE, with an uncertainty of +/- 0.01 degrees.

Solar Position Algorithm (SPA): SPA calculates the location of the sun in the sky (and various other values). Valid from the year -2000 to 6000 CE, with an uncertainty of +/- 0.0003 degrees.

Please read the disclaimer before using these products.
The RReDC has more information about these algorithms and the C source codes.

[NREL] [MIDC]