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Add original downloaded versions of NREL sunpos code.
1 jpye 2582
2    
3     /////////////////////////////////////////////
4     // HEADER FILE for SPA.C //
5     // //
6     // Solar Position Algorithm (SPA) //
7     // for //
8     // Solar Radiation Application //
9     // //
10     // May 12, 2003 //
11     // //
12     // Filename: SPA.H //
13     // //
14     // Afshin Michael Andreas //
15     // afshin_andreas@nrel.gov (303)384-6383 //
16     // //
17     // Measurement & Instrumentation Team //
18     // Solar Radiation Research Laboratory //
19     // National Renewable Energy Laboratory //
20     // 1617 Cole Blvd, Golden, CO 80401 //
21     /////////////////////////////////////////////
22    
23     ////////////////////////////////////////////////////////////////////////
24     // //
25     // Usage: //
26     // //
27     // 1) In calling program, include this header file, //
28     // by adding this line to the top of file: //
29     // #include "spa.h" //
30     // //
31     // 2) In calling program, declare the SPA structure: //
32     // spa_data spa; //
33     // //
34     // 3) Enter the required input values into SPA structure //
35     // (input values listed in comments below) //
36     // //
37     // 4) Call the SPA calculate function and pass the SPA structure //
38     // (prototype is declared at the end of this header file): //
39     // spa_calculate(&spa); //
40     // //
41     // Selected output values (listed in comments below) will be //
42     // computed and returned in the passed SPA structure. Output //
43     // will based on function code selected from enumeration below. //
44     // //
45     // Note: A non-zero return code from spa_calculate() indicates that //
46     // one of the input values did not pass simple bounds tests. //
47     // The valid input ranges and return error codes are also //
48     // listed below. //
49     // //
50     ////////////////////////////////////////////////////////////////////////
51    
52     #ifndef __solar_position_algorithm_header
53     #define __solar_position_algorithm_header
54    
55    
56     //enumeration for function codes to select desired final outputs from SPA
57     enum {
58     SPA_ZA, //calculate zenith and azimuth
59     SPA_ZA_INC, //calculate zenith, azimuth, and incidence
60     SPA_ZA_RTS, //calculate zenith, azimuth, and sun rise/transit/set values
61     SPA_ALL, //calculate all SPA output values
62     };
63    
64     typedef struct
65     {
66     //----------------------INPUT VALUES------------------------
67    
68     int year; // 4-digit year, valid range: -2000 to 6000, error code: 1
69     int month; // 2-digit month, valid range: 1 to 12, error code: 2
70     int day; // 2-digit day, valid range: 1 to 31, error code: 3
71     int hour; // Observer local hour, valid range: 0 to 24, error code: 4
72     int minute; // Observer local minute, valid range: 0 to 59, error code: 5
73     int second; // Observer local second, valid range: 0 to 59, error code: 6
74    
75     double delta_t; // Difference between earth rotation time and terrestrial time
76     // It is derived from observation only and is reported in this
77     // bulletin: http://maia.usno.navy.mil/ser7/ser7.dat,
78     // where delta_t = 32.184 + (TAI-UTC) + DUT1
79     // valid range: -8000 to 8000 seconds, error code: 7
80    
81     double timezone; // Observer time zone (negative west of Greenwich)
82     // valid range: -18 to 18 hours, error code: 8
83    
84     double longitude; // Observer longitude (negative west of Greenwich)
85     // valid range: -180 to 180 degrees, error code: 9
86    
87     double latitude; // Observer latitude (negative south of equator)
88     // valid range: -90 to 90 degrees, error code: 10
89    
90     double elevation; // Observer elevation [meters]
91     // valid range: -6500000 or higher meters, error code: 11
92    
93     double pressure; // Annual average local pressure [millibars]
94     // valid range: 0 to 5000 millibars, error code: 12
95    
96     double temperature; // Annual average local temperature [degrees Celsius]
97     // valid range: -273 to 6000 degrees Celsius, error code; 13
98    
99     double slope; // Surface slope (measured from the horizontal plane)
100     // valid range: -360 to 360 degrees, error code: 14
101    
102     double azm_rotation; // Surface azimuth rotation (measured from south to projection of
103     // surface normal on horizontal plane, negative west)
104     // valid range: -360 to 360 degrees, error code: 15
105    
106     double atmos_refract;// Atmospheric refraction at sunrise and sunset (0.5667 deg is typical)
107     // valid range: -5 to 5 degrees, error code: 16
108    
109     int function; // Switch to choose functions for desired output (from enumeration)
110    
111     //-----------------Intermediate OUTPUT VALUES--------------------
112    
113     double jd; //Julian day
114     double jc; //Julian century
115    
116     double jde; //Julian ephemeris day
117     double jce; //Julian ephemeris century
118     double jme; //Julian ephemeris millennium
119    
120     double l; //earth heliocentric longitude [degrees]
121     double b; //earth heliocentric latitude [degrees]
122     double r; //earth radius vector [Astronomical Units, AU]
123    
124     double theta; //geocentric longitude [degrees]
125     double beta; //geocentric latitude [degrees]
126    
127     double x0; //mean elongation (moon-sun) [degrees]
128     double x1; //mean anomaly (sun) [degrees]
129     double x2; //mean anomaly (moon) [degrees]
130     double x3; //argument latitude (moon) [degrees]
131     double x4; //ascending longitude (moon) [degrees]
132    
133     double del_psi; //nutation longitude [degrees]
134     double del_epsilon; //nutation obliquity [degrees]
135     double epsilon0; //ecliptic mean obliquity [arc seconds]
136     double epsilon; //ecliptic true obliquity [degrees]
137    
138     double del_tau; //aberration correction [degrees]
139     double lamda; //apparent sun longitude [degrees]
140     double nu0; //Greenwich mean sidereal time [degrees]
141     double nu; //Greenwich sidereal time [degrees]
142    
143     double alpha; //geocentric sun right ascension [degrees]
144     double delta; //geocentric sun declination [degrees]
145    
146     double h; //observer hour angle [degrees]
147     double xi; //sun equatorial horizontal parallax [degrees]
148     double del_alpha; //sun right ascension parallax [degrees]
149     double delta_prime; //topocentric sun declination [degrees]
150     double alpha_prime; //topocentric sun right ascension [degrees]
151     double h_prime; //topocentric local hour angle [degrees]
152    
153     double e0; //topocentric elevation angle (uncorrected) [degrees]
154     double del_e; //atmospheric refraction correction [degrees]
155     double e; //topocentric elevation angle (corrected) [degrees]
156    
157     double eot; //equation of time [minutes]
158     double srha; //sunrise hour angle [degrees]
159     double ssha; //sunset hour angle [degrees]
160     double sta; //sun transit altitude [degrees]
161    
162     //---------------------Final OUTPUT VALUES------------------------
163    
164     double zenith; //topocentric zenith angle [degrees]
165     double azimuth180; //topocentric azimuth angle (westward from south) [-180 to 180 degrees]
166     double azimuth; //topocentric azimuth angle (eastward from north) [ 0 to 360 degrees]
167     double incidence; //surface incidence angle [degrees]
168    
169     double suntransit; //local sun transit time (or solar noon) [fractional hour]
170     double sunrise; //local sunrise time (+/- 30 seconds) [fractional hour]
171     double sunset; //local sunset time (+/- 30 seconds) [fractional hour]
172    
173     } spa_data;
174    
175     //Calculate SPA output values (in structure) based on input values passed in structure
176     int spa_calculate(spa_data *spa);
177    
178     #endif

john.pye@anu.edu.au
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