Aerodynamics of Ground-Mounted Solar Panels: Test Model Scale Effects[1][edit | edit source]

Abstract: Most boundary-layer wind tunnels (BLWTs) were built for testing models of large civil engineering structures that have geometric scales ranging from 1:500 to 1:100. However, producing aerodynamic models of the solar panels at such scales makes the modules too small, resulting in at least two technical problems. First, the resolution of pressure data on such small models becomes low. Second, the test model may be placed in the lower portion of the boundary-layer that is not a true representative of a real world scenario, due to high uncertainty in wind velocity. To alleviate these problems, development of a standardized testing protocol is very important. Such protocol should account for different time and geometric scales to design appropriate wind tunnel experiments that can allow accurate assessment of wind loads on the solar panels. The current paper systematically investigates the sensitivity of wind loads to testing ground-mounted solar panels, both experimentally (in a BLWT) and numerically (by computational fluid dynamics (CFD)), at different geometric scales. While mean loads are not significantly affected by the model size, peak loads are sensitive to both the geometric scale and the spectral content of the test flow. However, when the objective is to predict 3-s (three seconds) peak loads, large models can be tested in a flow that has reduced high-frequency turbulence.

Wind-Induced Pressures on Solar Panels Mounted on Residential Homes[2][edit | edit source]

Abstract: This paper presents wind load investigations on solar panel modules mounted on low-rise buildings with gable roofs that have two distinct slopes. Wind loads on the solar panels mounted on several zones of the roofs were systematically investigated in a boundary-layer wind tunnel for different wind directions. The results from the wind-tunnel investigation are compared with ASCE provisions for residential bare roofs. The comparison shows a good agreement with the ASCE standard provisions for the main force resisting system. Nevertheless, the cladding loads on individual modules may be lower or higher than those on the corresponding area of a bare roof (depending on their location and array configuration and the roof's slope). Avoiding the roof critical zones (zones 3 and 2) is recommended to avoid high net minimum pressures acting on the solar panel modules. Solar panels mounted in zone 1 are locally subjected to higher suction at their outer edges. This is most likely attributed to the effect of a raised secondary roof formed over the main roof. The impact of the secondary roof effects is noticeable for small modules compared with larger modules.

Aerodynamic Loads on Solar Panels[3][edit | edit source]

Abstract: The existing literature has limited aerodynamic data for the evaluation of design wind loads for solar panels. Furthermore, there are no provisions in building codes and standards to guide the design of these types of structures for wind. This paper presents a systematic wind tunnel study to evaluate wind loads on solar panels mounted on low-rise gable buildings. A preliminary geometric scale effect study using a simple isolated solar panel was carried out to permit design appropriate wind tunnel experiments. Following the scale effect study, wind loads on solar panels mounted on different critical zones of low-rise residential roof are systematically investigated. The results of the current paper provide useful information for the design of the solar panels.

  • limited lit and data for wind loads on PV
  • no bldg code provisions for bldg. these structures
  • -->conservative designs = unsafe structure or overestimated aero load (barkaszi and o'brien 2010)
  • scaling parameter issues = 10%, 25% error loads & Cpp (Stathopoulos and Surry 1983; Zhao et al. 1996)
  • geo scale effect study
  • panels tested at diff critical zones on low-rise roof (corners, edge)=, zone1-3)
  • code over estimates (zone3,2) & underestimates (zone1 & gap config) net pressure

Use of the Wind Tunnel Test Method for Obtaining Design Loads on Roof-Mounted Solar Arrays" by (Kopp and Banks)[edit | edit source]

  • Method 3 in ASCE 7-05
  • Describes different requirements to wind test for different mounting arrangements
  • ASCE 7-05 ASCE 7-10
  • 7-10 wind loads on structures
  • 7 conditions for acceptable results
  • Unusual structures (like solar)
  • Atmospheric Boundary Layer (ABL) wind tunnel
  • Other wind tunnels if with care
  • Focuses on tilted roof mounted solar arrays low rise flat roof
  • Seven requirements, four groups: Model approach flow correctly, Model panels and surroundings correctly, Account for tunnel wall, Adequate instrumentation
  • Two issues to be discussed: surroundings and scale
  • Tests must include the roof
  • Flow modeling requirements in Tieleman 2003
  • ASCE 7 does not permit the use of CFD for wind loads
  • Simplest approach – building config with largest magnitude
  • Low profile roof mounted arrays on industrial low rise with nearly flat roof – min req test with basic layout with min 8 rows
  • Flow simulation details in Kopp et al 2012
  • Example test case described – 12 rows of 12 modules each, landscape mode width 1m length 1.65m tilt 30deg toward south
  • Zoning important for roof caused wind effects

Wind Design Practice and Recommendations for Solar Arrays on Low-Slope Roofs" by (Maffei, Telleen and Ward)[edit | edit source]

  • Paper to discuss recommendations for solar roof design as have not been included in ASCE standards
  • Terminology discussed for Module, panel, array
  • Roof mounted systems vary in attachment method, panel interconnectedness, shrouding
  • Panel arrangement flowchart shows ground-mounted systems as pile-supported or ballasted
  • Breaks down the three main roof-top systems (roof-bearing, fully framed, building-integrated)
  • Wind pressure/suction on surface of array
  • Solar array surface area is flat top and bottom of panel
  • Sloped panels-vertical lift and horizontal drag
  • Wind pressures from wind environment, shape of building, location on roof, aerodynamics of array
  • Wind pressure varies with time-short term peaks on particular array elements
  • Design pressure p based on velocity pressure q and gust effect factor
  • Results in internal structural forces
  • Specific codes for arrays lacking but can follow other requirements
  • Include no risk to life from such as breaking from roof, sliding over edge, exceeding carrying capacity
  • Adequate displacement capacity of electrical systems
  • Equations of load combination design are given
  • Asce 7-10 chapter 30-31 methods: simplified, analytical, wind tunnel
  • Simplified and analytical more prescriptive
  • Wind tunnel more appropriate for determining design pressure coefficient
  • Section 31.2 – wind tunnel scaling, modeling, instrumentation
  • Step two: define purpose of test
  • Discusses different kinds of tests: pressure, force-balanced, fly away
  • Different wind tunnel tests not cross compatible
  • Testing program to determing design pressure coefficients
  • Based on varying parameters in order to design system
  • Design curves in asce 7-10 for relationship of tributary area and wind pressure
  • Pressure coefficient decreases wrt area
  • Pressure curves are available for various roof cladding systems
  • Test show curve underemphasize effect of tributary area for solar array
  • Curve may be unconservative for wind pressure on small area
  • Curve should envelope data
  • Power function shows power proportional to area
  • For some pressure coefficients P decrease wrt area causing issues and having potential nonconvergence
  • Some design principles covered
  • Up down and horizontal wind forces
  • Consider worst case scenario, uniform pressure over whole array and gusts which target specific parts
  • Ballast check where there is liftoff and ensure internal structure
  • For fully framed attached check attachment joint
  • Wind pressure depends on tributary area
  • Array resist pressure acting on area any size
  • Design methodology has 4 steps
  • Step one test one module
  • Step two whole array
  • Step three local gust cases
  • Step four downward pressure
  • Had calc for individual module – models for interconnected systems (which resist more force by distribution)
  • Non linearity important consideration
  • Testing to help understand behavior
  • Summarizes building code req
  • Categorize panel support systems
  • Data such as pressure coefficients
  • Wind tunnel requirements

How to Calculate Wind Loads[edit | edit source]

ASCE. 2010. Minimum Design Loads for Buildings and Other Structures. ASCE/SEI Standard 7-10. A. Kopp, Gregory & Farquhar, Steve & J. Morrison, Murray. (2012). Aerodynamic mechanisms for wind loads on tilted, roof-mounted, solar arrays. Journal of Wind Engineering and Industrial Aerodynamics. 111. 40–52. 10.1016/j.jweia.2012.08.004.

Warsido, Workamaw P. et al. "Influence of Spacing Parameters on the Wind Loading of Solar Array." Journal of Fluids and Structures 48 (2014): 295–315. Web.

Reina, Giovanni Paolo, and De Stefano, Giuliano. "Computational Evaluation of Wind Loads on Sun-Tracking Ground-Mounted Photovoltaic Panel Arrays." Journal of Wind Engineering & Industrial Aerodynamics 170 (2017): 283–293. Web.

Stathopoulos, Ted, Zisis, Ioannis, and Xypnitou, Eleni. "Local and Overall Wind Pressure and Force Coefficients for Solar Panels." Journal of Wind Engineering & Industrial Aerodynamics 125.C (2014): 195–206. Web.

Abiola-Ogedengbe, Ayodeji, Hangan, Horia, and Siddiqui, Kamran. "Experimental Investigation of Wind Effects on a Standalone Photovoltaic (PV) Module." Renewable Energy 78 (2015): 657–665. Web.

Wind Loading on Ground Mounted Arrays[edit | edit source]

WIND LOADS ACTING ON PV PANELS AND SUPPORT STRUCTURES WITH VARIOUS LAYOUTS (Daisuke Somekawa,Tetsuro Taniguchi, Yoshihito Taniike)[edit | edit source]

Wind Loading on Solar Panels at Different Inclination Angles (Mehrdad Shademan, Horia Hangan)[edit | edit source]

Mechanics[edit | edit source]

Tension Tests on Driven Fin Piles for Support of Solar Panel Arrays[edit | edit source]

Abstract Foundations for small solar installations can have a variety of forms, including cast-in-place concrete, precast concrete, driven piles, and helical screw-piles. A small installation of 70 solar panels was developed to supply power to the Agricultural Experiment Station at the University of Massachusetts. The contractor elected to install driven pipe piles to support the elevated solar panels, however, some questions arose as to the uplift capacity of the piles. In order to resolve the issues, a series of tension tests were performed at the site. In this paper results of tension tests on driven fin piles proposed to support the solar panel arrays are presented. The piles consisted of steel open pipe piles with four fins welded onto the outside to increase the uplift resistance. Three different diameter piles were installed and tested. All piles were driven to a depth of 8 ft. Tests were performed on plain pipe piles without fins and on piles with different configurations of fins in order to provide a comparison of any improvement in tension behavior provided by the fins. The site consisted of an alluvial sandy silt deposit. The results of the site investigation and the pile load tests are presented.

Application of ARMA Model in Forecasting Aluminum Price[4][edit | edit source]

Abstract: Aluminum price is very complicated for containing many uncertainty factors. In recent years, ARMA model has been widely used to make models for financial temporal series which have high fluctuation frequency, because it can grasp the dynamic characteristics of temporal series. The article proposes a price prediction method based upon ARMA model through the analysis of Aluminum price. The result has proved that the model can fit Aluminum price fluctuation quite well and prediction results prove efficiency and dependability.

[Basic steel design with LRFD][5][edit | edit source]

System for scenario planning and forecasting world prices for steel and metallurgical raw materials[6][edit | edit source]

Abstract:The article describes the methodology for construction and the main results obtained by implementing a scenario and modeling system intended for generating scenarios and forecasting the long-term performance of the world prices for steel and metallurgical raw materials.

[Shigley's mechanical engineering design][7][edit | edit source]

[Introduction to Engineering Mechanics: A Continuum Approach][8][edit | edit source]

[Engineering design : a systematic approach][9][edit | edit source]

[Analysis of metallurgical failures ][10][edit | edit source]

[Failure of materials in mechanical design : analysis, prediction, prevention][11][edit | edit source]

[Mechanics of Materials: Textbook for a Fundamental Mechanics Course][12][edit | edit source]

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  1. Aly, Aly Mousaad, and Bitsuamlak, Girma. "Aerodynamics of Ground-Mounted Solar Panels: Test Model Scale Effects." Journal of Wind Engineering & Industrial Aerodynamics, vol. 123, no. PA, Elsevier Ltd, Dec. 2013, pp. 250–60, doi:10.1016/j.jweia.2013.07.007.
  2. Aly, Aly Mousaad, and Bitsuamlak, Girma. "Wind-Induced Pressures on Solar Panels Mounted on Residential Homes." Journal of Architectural Engineering, vol. 20, no. 1, American Society of Civil Engineers, Mar. 2014, p. , doi:10.1061/(ASCE)AE.1943-5568.0000132.
  3. Aly, A.M., Bitsuamlak, G., n.d. Aerodynamic Loads on Solar Panels, in: Structures Congress 2013.
  4. Y. Ru and H. J. Ren, "Application of ARMA Model in Forecasting Aluminum Price", Applied Mechanics and Materials, Vols. 155-156, pp. 66-71, 2012
  5. Galambos, T. V. Basic Steel Design with LRFD. Upper Saddle River, N.J: Prentice Hall, 1996.
  6. Malanichev, A. "System for Scenario Planning and Forecasting World Prices for Steel and Metallurgical Raw Materials." Studies on Russian Economic Development, vol. 25, no. 3, Pleiades Publishing, May 2014, pp. 251–58, doi:10.1134/S1075700714030071.
  7. Budynas, Richard G. Shigley's Mechanical Engineering Design. 9th ed. McGraw-Hill Series in Mechanical Engineering. New York: McGraw-Hill, 2011.
  8. Rossmann, Jenn Stroud, and Clive L Dym. Introduction to Engineering Mechanics: A Continuum Approach. Boca Raton, FL: CRC Press, 2009.
  9. Pahl, G. Engineering Design: A Systematic Approach. London ; New York: Springer, 1996.
  10. Colangelo, Vito J. Analysis of Metallurgical Failures. Wiley Series on the Science and Technology of Materials. New York: Wiley, 1974.
  11. Collins, J. A. Failure of Materials in Mechanical Design: Analysis, Prediction, Prevention. New York: Wiley, 1981.
  12. Thiagarajan, Ganesh. Mechanics of Materials: Textbook for a Fundamental Mechanics Course. Mission, KS: Schroff Development Corp, 2009.