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ARRAY HAS INSTALLED +13,000 MILES OF TRACKERS
“Array has the most extensive track record of any PV tracker vendor.”
– Greentech Media Research, Global Tracker Landscape Report 2017
Munich,Germany
Hawaii,USA
Vast experience provides timeless reliability
16,000+ MW Years of Operation
TÜV Rheinland
• Founded in 1872, TÜV Rheinland is a global leader in independent engineering services, ensuring quality and safety for people, the environment, and technology in nearly all aspects of life. • Due to TÜV’s extensive experience with solar power plants,
they support their clients in all project phases and ensure plant safety and reliability.
Risk & Economic Analysis
The report analyzes the economics and risks of two solar tracker architectures.1. The first architecture is a centralized system
driven by a single motor, linked by a rotating driveline to multiple tracker rows.
2. The second architecture is a decentralized system where each row operates as a self-contained unit with a dedicated photovoltaic (PV) panel, battery, motor, and other components.
Download the report here: http://www.arraytechinc.com/tuv-report-findings/
TÜV’s in-depth process
Summary of Architecture 1
& 2
Summary of Failure Modes
and High Ricks
Components
Comparative Failure Modes
and Effects Analysis
(FMEA) and Cost Priority
Number (CPN) Analysis
Cost of Failure Analysis
NPV and LCOE Calculations
Comparative failure mode effects analysis (FMEA)
FMEA is an important factor in determining LCOE/NPV often discounted or given cursory attention, this factor can make or break a project
Example of components studied: • Motor Drive• Tracker control• Communications• Sensors
Key component selection
(less than 30 year life)
Architecture 1 Architecture 2
Tracker Control 30.5 units, 15 years 3400 units, 15 years
Site Control 1 unit, 15 years 8 units, 15 years
Battery - 3400 units, 7 years
Communication & Sensors 1 unit, 15 years 3400 units, 15 years
Motor Drive 122 units, 30 years 3400 units, 15 years
Transmission Worm Gear: 3400 units, 30 years
Slew Drive: 3400 units, 30 years
Torque Tube 27200 units, 30 years 34000 units, 30 years
Mechanical End Stop 34000 units, 30 years 34000 units, 30 years
Bearings Included in End Stop 34000 units, 30 years
Vibration Dampeners 6800 units, 30 years 6800 units, 30 years
Steel Structure 3400 units, 30 years 3400 units, 30 years
FMEA: Number of parts vs life expectancy
Total Number of Parts
Architecture 1 74954Architecture 2 129208
0
20000
40000
60000
80000
100000
120000
140000
Less components. Fewer failures. More reliable.
ArrayDuraTrackHZv3 DecentralizedRow
TrackerElectricalandElectromechanicalComponents UnitsPer100MW UnitsPer100MW
Activestowcomponents(anemometers) 0 20Motors 122 3400Inclinometers 0 3400Controlelectronics 31 3400Ancillarysolarmodules 0 3400Wirelessradios 0 3400BatteryChargecontrollers 0 3400Batteries 0 3400TOTALCOMPONENTSper100MW 149 25,220
153TOTAL
COMPONENTS
23,820 TOTAL
COMPONENTS
Cyber Attack
A system is only as strong as its weakest link
Anemometer
With an electrical stow design, any failure of ANY link in the chain leaves the system vulnerable to catastrophic failure during wind and snow events
Battery for Central Controller
Coaxial Controller Panel Supply
Central Controller Electronics
Radio
Radio
Row Controller Electronics
Row Controller Power Supply
Row Controller Motor
Row Controller Battery
Unscheduled maintenance costs
• Costs were calculated using a Cost of Failure (CoF) methodology, which estimates the expected market cost of a failure.• Cost of failure
calculations are unique to each architecture as they are a function of cost of the part being replaced, labor, and production losses.
Unscheduled O&M Leads to Significant Cost*
With Centralized Trackers: 1 repair/year for 100 MW site, and far fewer truck rolls†
With Decentralized Trackers:794 repairs/year (2 per day) for 100 MW site, and far more truck rolls†
433 × fewer number of service hours†
†Verified by 3rd party data from TÜV
*Verified by 3rd party data from TÜV
7% Lower LCOE*
CAPEX
Highest uptime in the industry delivers
maximum energy production
Production
OPEX
Streamlined installation and commissioning reduces time onsite
and saves upfront cost
The lowest scheduled and unscheduled O&M achieves the highest savings
7% Lower LCOE†
†Verified by 3rd party data from TÜV
*Verified by 3rd party data from TÜV
Wind calculations, what can go wrong? • Use of existing code pressure
coefficients & methods• Mono-slope roof coefficients
developed for 4-leg table• Improper dynamic analysis
(1 Hz is not safe!)
• Too low or misapplied wind tunnel coefficients• Small area concentrations,
directionality, tracker angles, GCR not considered
• Effects on misaligned rows
• Ignore specific effects of wind • Torsion, dynamic behavior
• Stow methodology too heavily relied upon
• Forces may be magnified by 3-4X in some cases!
Post Hurricane Maria damage in Puerto Rico
Proper wind calculations• Determine tracker e requirements for
wind/snow/seismic/etc. considering• Stow strategy• Local studies and code development• Wind tunnel analysis
• Develop dynamic model of the system• Structural natural frequencies• Damping mechanisms• Wind forcing functions
• Design for max load combinations according to code requirements (generally wind+snow)• Will stow mechanism see same loads as structure?• Choose max load conditions at each tracker position• Incorporate dynamic response into static load
combinations as appropriate• Local and edge forces amplified compared to system-
level
• Analyze worst case events on structural and mechanical components• Fatigue• Max load
Questions?• There may be more components in some systems but those components
are far less expensive. How does that affect O&M costs?• What components should I pay particular attention to? Are there
components which are more prone to failure?• Of the various tracker system architectures which has proven to be the
most reliable?• You raise the question of catastrophic failure. Is this a common
occurrence? If so why haven’t we heard more about it?
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