Analyzing Risk & Economic Impact of Two Solar Tracker Architectures November 2017
Vast experience provides timeless reliability ARRAY HAS INSTALLED +13,000 MILES OF TRACKERS Array has the most extensive track record of any PV tracker vendor. Munich, Germany 16,000+ MW Years of Operation Greentech Media Research, Global Tracker Landscape Report 2017 Hawaii, USA
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 selfcontained 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)
FMEA: Number of parts vs life expectancy 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 140000 120000 100000 80000 60000 40000 20000 0 Total Number of Parts Architecture 1 74954 Architecture 2 129208
Less components. Fewer failures. More reliable. Array DuraTrack HZ v3 Decentralized Row Tracker Electrical and Electromechanical Components Units Per 100 MW Units Per 100 MW Active stow components (anemometers) 0 20 Motors 122 3400 Inclinometers 0 3400 Control electronics 31 3400 Ancillary solar modules 0 3400 Wireless radios 0 3400 Battery Charge controllers 0 3400 Batteries 0 3400 TOTAL COMPONENTS per 100 MW 149 25,220 153 TOTAL COMPONENTS 23,820 TOTAL COMPONENTS
A system is only as strong as its weakest link 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 Anemometer Coaxial Controller Panel Supply Radio Row Controller Electronics Row Controller Battery Battery for Central Controller Cyber Attack Central Controller Electronics Radio Row Controller Power Supply Row Controller Motor
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 * * Verified by 3 rd party data from TÜV 433 fewer number of service hours 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 Verified by 3 rd party data from TÜV
LCOE & NPV findings
TÜV Spreadsheet: 30 year warranty
TÜV Spreadsheet: = Sched. Maintenance
TÜV Spreadsheet: 30% discount
TÜV Spreadsheet: Can it pencil?
TÜV Spreadsheet: But wait a second
7% Lower LCOE * * Verified by 3 rd party data from TÜV CAPEX Streamlined installation and commissioning reduces time onsite and saves upfront cost Production Highest uptime in the industry delivers maximum energy production 7% Lower LCOE OPEX The lowest scheduled and unscheduled O&M achieves the highest savings Verified by 3 rd party data from TÜV
Is your site destined for catastrophic failure?
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 systemlevel Analyze worst case events on structural and mechanical components Fatigue Max load
22 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?