[SOL_POS] Solar position calculation

Use

Position and angle of the blinds are controlled in relationship to the solar position (anti-glare). This prevents direct solar radiation in the building, but permits as much light as possible into the building.

Calculate solar position

SOL_POS calculates the current solar position as per DIN 5034-2 from the following values:

• Local time and date as per the system time on the automation station.
• Settings for the time zone (UTC offset) and daylight saving time.
• Geographical longitude (Eastern longitude) [Lngit] and latitude (Northern latitude) [Latit].

The calculated solar position is displayed using the following angle:

• [SolAzmth] = Solar azimuth (solar angle to the north)
• [SolEtHor] = Solar elevation angle (solar elevation from horizon)

Configure system time

The system time on the automation station is set as the date and time. The UTC offset and summer/winter time state is configured as a time zone. The time zone is configured on the device object for the automation station.

Calculate solar elevation angle relative to a surface

SOL_POS calculates the solar elevation angle relative to a configured surface. The position of the surface is configured at inputs Tilt angle of tilted surface [TltSrf] and aspect angle tilted surface [AspSrf].

Configure surface position

Calculating solar radiation relative to a surface

SOL_POS calculates the solar radiation on a configured surface relative to a surface that is vertically facing the sun (= maximum solar radiation).

Influences such as blur or scatter are not considered.

The calculated solar radiation [SolRdSrf] on the surface (with aspect angle [AspSrf] and tilt [TltSrf]) is calculated as a % of maximum solar radiation (100%).

Sunrise, sunset, day/night

SOL_POS calculates sunrise [Sunrise] and sunset [Sunset] and supplies these values to the outputs.

The indication for day or night is provided on output [NdaySta].

Day ([NdaySta] = 1) is displayed if the solar elevation angle from horizon [SolEtHor] is greater than 0°.

Configure and apply simulation

SOL_POS can simulate throughput time as of a specific time for commissioning and testing. During the simulation, the corresponding values for the simulated time are provided to the outputs. Set input [EnSim] to 1 to activate the simulation. Input [SimDaTi] can be used as the start time in the simulation.

Input [TiFacSim] can be used to accelerate or slow down the simulated time:

• [TiFacSim] = 1.0: Simulation is running in realtime.
• [TiFacSim] = 0.0: Time is stopped.
• [TiFacSim] > 1.0: Time is faster than realtime.
• [TiFacSim] = 1440: Simulates a day in a minute in realtime.

Commissioning:

• It is assumed that the time zone (UTC Offset) for the simulation is the same as the time zone in the system settings.
• No summer/winter changeover occurs as part of the simulation. The present (per system time) valid summer/winter time status is always used.
• The simulated time (for TiFacSim > 0) does not always operate consistently due to rounding errors.

Diagrams

Key