SOLAR_NREL¶
| Available as of PLC runtime system: | V1.3 and above |
| Included in library: | SolarNREL_AC500_V22.lib |
| Type | Type_Function_Block_No_History |
| Group | Package of Function Blocks to get the sun position |
This Function Block calculates the solar position depending on the date, time, and localization. It also includes a function that corrects the value of the elevation thanks to the local pressure, temperature and refraction of atmosphere at sunrise and sunset. This function embeds the NREL’s algorithm which can be found on the NERLs website: http://rredc.nrel.gov/solar/codesandalgorithms/spa
The limitation of this function is the number of outputs which are the azimuth, elevation (uncorrected) and corrected elevation. These outputs are the topocentric coordinates of the sun which use the observer’s location as the center of the coordinate system.
The end-user may use the RTC of the AC500 system by using the CLOCK Function Block of the library named SysExt_AC500_V10.lib or may use any other source to calculate the solar position.
Any additional information about the algorithm can be found on the NREL website: http://www.nrel.gov/
Table below shows the size of used data for NREL Function Block and execution time for each CPU type.
| PM583 | PM591 | PM564 | |
|---|---|---|---|
| Data Size | 4731 bytes | 4731 bytes | 4731 bytes |
| Program Size | 79706 bytes | 43270 bytes | 80406 bytes |
| Execution Time | 65 ms | 1 ms | 120 ms |
In case of a PM58x and PM5X4 CPU´s, the program which calls this function block must be integrated in a dedicated task with a correct value of watchdog (or with watchdog disabled).