SolarNrel (FB)

FUNCTION_BLOCK SolarNrel EXTENDS AbbLConCA

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. 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

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. A falling edge (Enable = FALSE) aborts the operation. During Aborting the Busy is still TRUE. Afterward all outputs are reset.	AbbLConCA
Output	Busy	BOOL	FALSE	Operation is running (while output Error is FALSE)	AbbLConCA
	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.	AbbLConCA
Input	Year	INT	2022	2 : Year [2000..6000]
	Mon	INT	6	3 : Month [1..12]
	Day	INT	1	4 : Day [1..31]
	Hour	INT	10	5 : Hour [0..24]
	Minute	INT	10	6 : Minute [0..59]
	Sec	INT	25	7 : Second [0..59]
	Timezone	LREAL	0	8 : Observer time zone (negative west of Greenwich) [-12..12] (degrees)
	DeltaTime	LREAL	0	9 : DeltaT = Terrestrial Time (TT) - Universal Time (UT) [-8000..8000] (seconds)
	Latitude	LREAL	0	10 : Observer latitude (negative south of equator) [-90..90] (degrees)
	Longitude	LREAL	0	11 : Observer longitude (negative west of Greenwich) [-180..180] (degrees)
	Altitude	LREAL	0	12 : Observer elevation / Altitude [-5000 .. 5000] (meters)
	Pressure	LREAL	0	13 : Local pressure [0..5000] (millibars)
	Temperature	LREAL	0	14 : Local temperature [-273..6000] (degrees Celsius)
	AtmosRefraction	LREAL	0	15 : Atmospheric refraction at sunrise & sunset (typical:0.5667) [-5..5] degrees)
Output	ErrorID	ERROR_ID		3 : Error code which indicates which input is erroneous
	Azimuth	LREAL	0	4 : Topocentric azimuth angle (eastward from north) [ 0..360] (degrees)
	ElevationUncorrected	LREAL	0	5 : Topocentric elevation angle (uncorrected) (degrees)
	ElevationCorrected	LREAL	0	6 : Topocentric elevation angle (corrected) (degrees)

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)