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Simply follow the sunMaximize the yields of solar power plants with solar tracking control

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up to 0.0003accuracy with an astronomical algorithm and SIMATIC S7-1200

Simply follow the sunMaximize the yields of solar power plants with solar tracking control

www.siemens.com/solar-industry

You got to keep them moving

It goes without saying that solar power plants need to have their photovoltaic panels or mirrors aligned perpendicular or at a certain angle to the sun to operate at peak efficiency. Panel alignment maxi-mizes energy yields up to 3040 percent in cell-based photovoltaics (PV), while precise alignment is an unconditional prerequisite for stable and efficient power generation in concentrated photo-voltaics (CPV) and concentrated solar power (CSP). However, the suns position in the sky is constantly changing. The innovative and highly efficient single-axis and dual-axis solar tracking control system by Siemens can control the azimuthal and zenithal movements of PV and CPV panels and CSP mirrors, constantly correcting their position and pointing them directly towards the sun. Thats how the Siemens tracking control system, which is based on SIMATIC S7-1200, contributes to a considerable increase of electricity generation.

Your benefits at a glance: Innovative, highly efficient control system Based on industry-proven technology Modular design makes the control system suitable for PV, CPV, and CSP applications The open interfaces of SIMATIC S7-1200 support communication with the solar parks other components. Communication with Siemens com-ponents is optimized thanks to Totally Integrated Automation (TIA) Software library supports the integrati-on of several functionalities Flexibly expandable thanks to modular design

Solar tracking control systems by Siemens are based on SIMATIC S7-1200. They provide an optimal solution for maximizingthe energy yield of solar power plants.

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Seamless integration thanks to TIA and TIA Portal

Benefits of TIA Reduced time to market thanks to reduced development time Control components of each application scalable to individual needs Simplified international deployment of tracking systems Long-term investment security Reduced total cost of ownership Quick, easy, and flexible configuration of tracking control solutions Reduced commissioning time

SIMATIC S7-1200 and TIA PortalThe Siemens solar tracking system is based on the SIMATIC S7-1200 controller, which defines a new dimen-sion in compact automation. It provides highest flexibility for smart solutions thanks to its scalable hardware and ensures accurate positioning with its 64-bit resolution. The controller also has a web server that makes it possible to access it with a web browser. SIMATIC S7-1200 is fully integrated in Totally Integrated Automation Portal (TIA Portal), the innovative engineering framework for all automation tasks. TIA Portal redefines engineering within TIA. It improves competitiveness by maximizing the return on investment for engineering with its intuitive operation, efficient engineering, and proven functionality.

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Siemens universal tracking control sys-tem suits all solar applications from sim-ple single-axis movement in PV applica-tions all the way to highly precise dual-axis movements in CPV systems. Each solar tracking unit is perfectly con-trolled by a SIMATIC S7-1200. A solar tracking unit can consist of one or several trackers. The configuration of a parks communication system is noticeably influenced by the locations geographical conditions. A practical solution for smaller parks is the formation of clusters that are connected in line using PROFINET. In these cases, a controller takes over superordinated functions such as the handling of wind alarms and time synchronization. In larger parks of more than 25 trackers, the combination of line and star connections is a feasible option.

In addition, various transmission media, such as optical fiber, can be used.SIMATIC S7-1200 software and hardware are expandable according to individual requirements. The onboard PROFINET interface and expansion modules with communication interfaces, such as PROFIBUS and Modbus, ensure easy inte-gration into the consistent communica-tion of the entire solar farm.

Applicable for solar farms of any size

Small-sized solar farm: e.g. up to 25 trackers merged to a single cluster

Communication Communication equipment by Siemens also facilitates the simple networking between the various solar tracking controllers, control and monitoring systems, and inverters.

SUB 1 *

SUB 6 *

SUB 5 *

SUB 2 *

SUB 7 *

SUB 3 *

SUB 8 *

SUB 4 *

SUB 9 *

*

*

*

*

HEAD Controller with superordinated task *

Field PG for commissioning

* SIMATIC S7-1200, controller for tracking task

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A SIMATIC solar position library for the tracking control system is available on demand. It calculates the general posi-tion of the sun for a certain location and time and controls the positioning of the solar tracker accordingly. Smart software-based features ensure appropriate con-trol in various weather conditions. Pre-cise axial and lateral adjustments are based on an astronomical algorithm featuring 64-bit arithmetic accuracy that even meets the requirements of CPV systems.

A central, PC-based HMI facilitates real-time status monitoring and control of all solar trackers.

Medium and large-scale solar farms: multiple clusters merged using e.g. SIMATIC S7-300 as HEAD PLC

Single-unit applicationThe solar tracker control libraries support solar power plant operators with several modes (manual, teach, and auto mode) of operation to match any application.

Internet

HEAD Controller with

superordinated task SIMATIC S7-300/400

SUB 1 *

SUB 2 *

SUB 3 *

SUB *

SUB *

SUB *

SUB *

SUB *

SUB *

SUB *

SUB *

SUB *

SCALANCE X

Park monitoring central system

Field PG for commissioning

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Precise tracking with astronomical algorithm Siemens tracking controls are designed to operate with-out sun sensors to ensure maximum availability. A cyclic astronomical algorithm evaluates the position of the sun on the basis of a comparison of latitude and longitude with the UTC time. SIMATIC S7-1200 uses the position of the sun, defined by azimuth and zenith, to align the panel perpendicular to the sun.The accuracy of the simple astronomical algorithm is suffi-cient for standard photovoltaic, including single- or dou-ble-axis PV solar trackers. The advanced astronomical algorithm SPA that was developed by the National Renew-able Energy Laboratory (NREL) for the U.S. Department of Energy (DOE)* is specified with a cutting-edge accuracy of +/-0.0003. This ensures an operational accuracy that is better than +/- 0.05 including mechanical tolerances if high precision gears are used. This kind of high precision astronomical algorithm is required for CPV and CSP solar tracker applications.

Both versions of the astronomical algorithm are included in a library that can be implemented easily in any solar tracking application. Siemens provides application exam-ples for solar tracking with SIMATIC S7-1200. They are automation concepts that are pre-developed to suit typi-cal tracking applications. They can be adapted to meet the most challenging requirements in order to ensure the highest possible degree of efficiency. The application examples comprise functions such as wind handling, which prevents damage to the panels in case of a storm by positioning the panel horizontally in order to minimize the wind load. The back tracking function ensures that all panels are kept from shading each other by adequate adaptive movements. Peak loads can be avoided with a function that clusters the solar panels into groups, which ensure that all solar trackers adjust their alignment accordingly but not at the same time.

*Neither NREL nor DOE endorse SIMATIC

Simple astronomical algorithm

Advanced astronomical algorithm

Photovoltaic (PV)

Concentrated Photovoltaic (CPV)

Parabolic Trough

Dish-Stirling

Central Receiver Tower

Conc

entra

ted

Sola

r Pow

er (C

SP)

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Photovoltaic (PV) Concentrated Photovoltaic (CPV)

Concentrated Solar Power (CSP)Parabolic Trough

Concentrated Solar Power (CSP)Central Receiver Tower

Concentrated Solar Power (CSP)Dish-Stirling

Solar Tracking

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Subject to change without prior notice Order No.: E20001-A140-T112-X-7600 Dispo 41513 21/43444 MI.AS.VM.XXSO.52.2.03 WS 08123. Printed in Germany Siemens AG 2012

The information provided in this brochure contains merely general descriptions or characteristics of performance which in case of actual use do not always apply as described or which may change as a result of further development of the products. An obligation to provide the respective character-istics shall only exist if expressly agreed in the terms of contract. All product designations may be trademarks or product names of Siemens AG or supplier com-panies whose use by third parties for their own purposes could violate the rights of the owners.

Siemens AG Industry Sector Solar Siemensallee 84 76187 KARLSRUHE GERMANY

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