SolarNrel (FB)

FUNCTION_BLOCK SolarNrel EXTENDS AbbLConC3

This function block calculates the position of the sun 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: https://midcdmz.nrel.gov/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.

Any additional information about the algorithm can be found on the NREL website: https://www.nrel.gov/

InOut:

Scope	Name	Type	Initial	Comment	Inherited from
Input	Enable	BOOL	FALSE	A rising edge (Enable = TRUE) starts the operation, the output Busy goes to TRUE. All other inputs are read and considered continuously. Execution will continue forever until a falling edge (Enable = FALSE) aborts the operation. During Aborting the Busy is still TRUE. Afterward all outputs are reset.	AbbLConC3
Output	Busy	BOOL	FALSE	Operation is running (while output Error is FALSE)	AbbLConC3
	Error	BOOL	FALSE	Operation is stopped with error (while output Busy is FALSE). This output is TRUE for at least one cycle or until Enable is set to FALSE. The output ErrorID gives more details about the error.	AbbLConC3
Input	Year	INT	2022	2: Year. Range 2000 to 6000
	Mon	INT	6	3: Month. Range 1 to 12
	Day	INT	1	4: Day. Range 1 to 31
	Hour	INT	10	5: Hour. Range 0 to 23
	Minute	INT	10	6: Minute. Range 0 to 59
	Sec	INT	25	7: Second. Range 0 to 59
	TimeZone	LREAL	0	8: Observer time zone(negative west of Greenwich) in hours. Timezone = Standard Time - Universal Time. Maximum value 12
	DeltaTime	LREAL	0	9: Difference between the earth rotation time and terrestrial time. It is derived from observation only and it is reported in this bulletin, where _T = 32.184 + (TAI-UTC) + _UT1 DeltaTime = Terrestrial Time (TT) - Universal Time (UT). [Range -8000 to 8000, Unit: Seconds]
	Latitude	LREAL	0	10: Observer latitude. Negative south of equator. [Range: -90 to 90. Unit: Degress]
	Longitude	LREAL	0	11: Observer longitude Nnegative west of Greenwich. [Range: -180 to 180. Unit: Degress]
	Altitude	LREAL	0	12: Observer elevation or Altitude. [Range: -5000 to 5000. Unit: Meters]
	Pressure	LREAL	0	13: Local pressure. [Range: 0 to 5000. Unit: Millibars]
	Temperature	LREAL	0	14: Local temperature. [Range: -273 to 6000. Unit: Celsius]
	AtmosRefraction	LREAL	0	15: Atmospheric refraction at sunrise & sunset. Typical:0.5667. [Range: -5 to 5. Unit: Degress]
Output	ErrorID	ERROR_ID		3 : Error code which indicates which input is erroneous
	Azimuth	LREAL	0	4 : Topocentric azimuth angle. Eastward from north. [Range of values 0 to 360. Unit: Degrees]
	ElevationUncorrected	LREAL	0	5 : Topocentric elevation angle.(uncorrected) [Range of values -90 to 90. Unit: Degrees]. Error: ±0.0004°
	ElevationCorrected	LREAL	0	6 : Topocentric elevation angle.(corrected) [Range of values -90 to 90. Unit: Degrees]. Error: ±0.0004°

Methods:

A_StartAction

B_CyclicAction

C_CleaningAction

D_AbortAction

E_ResetAction

Structure:

• SolarNrel.A_StartAction (METH)
• SolarNrel.B_CyclicAction (METH)
• SolarNrel.C_CleaningAction (METH)
• SolarNrel.D_AbortAction (METH)
• SolarNrel.E_ResetAction (METH)
• SolarNrel.zACTION_NREL_CALCULATE_EOT_AND_SUN_RISE (ACT)
• SolarNrel.zACTION_NREL_CALCULATE_GEOCENTRIC_SUN (ACT)
• SolarNrel.zACTION_NREL_VALIDATE_INPUTS (ACT)