Get our free book on rainwater now - To Catch the Rain.

Ground mount fixed tilt PV racking literature review

From Appropedia
Jump to: navigation, search

Sunhusky.png By Michigan Tech's Open Sustainability Technology Lab.

Wanted: Students to make a distributed future with solar-powered open-source 3-D printing.
Contact Dr. Joshua Pearce or Apply here

MOST: Projects and Publications, Methods, Lit. reviews, People, Sponsors
Updates: @ProfPearce on Twitter, @mturesearchmost on Instagram

OSL.jpg

Contribute to this Literature Review Although this page is hosted by MOST it is open edit. Please feel free to add sources and summaries. If you are new to Appropedia, you can start contributing after you create an account or log in if you have an existing account.

Contents

Design & Models[edit]

3-D printing solar photovoltaic racking in developing world [1][edit]

Abstract: The purpose of this paper is to provide a technical and economic evaluation of the value of the RepRap as an entry-level 3-D printer in the developing world and provide a cost effective solar photovoltaic (PV) racking solution to better serve the developing world and aid in the acceleration of their economic and socioeconomic growth. A customizable open-source PV racking concept is designed, prototyped for three types of modules, constructed into systems, and outdoor tested under extreme conditions for one year. An economic analysis is provided along with a technical evaluation of the system, which found the proposed racking system can be successfully printedwith RepRap 3-D printers and saves between 85% and 92% fromcommercially available alternatives depending on the plastic used for printing. In addition, the plastic parts proved able to withstand some of the harshest outdoor conditions and due to the free and open-source nature of the designs, it allows the system to be adapted to custom applications in any region in the world more easily than any commercial alternatives. The results indicate that the 3-D printable X-wire solar photovoltiac racking system has the potential to aid in the acceleration of solar deployment in the developing world by providing a low cost PV racking solution.

  • “X-Wire” PLA (83% savings) & HDPE (92% savings) backets + wiring (10, 20 deg)
  • Recyclebot + waste plastic option
  • Winter cond. Tested; economically compared to UNIRAC RM
  • Strength of Al vs. PLA
  • 3D printed V = 80% reduction of racking cost

Total U.S. Cost Evaluation of Low-Weight Tension-Based Photovoltaic Flat-Roof Mounted Racking[edit]

Abstract: The economics in the U.S. of solar photovoltaic (PV) systems is changing rapidly as the cost per unit power of PV modules has dropped quickly. These costs reductions have two important results: marked decrease in levelized cost of electricity (LCOE) into ranges competitive or better than traditional electricity-generation technologies and the economic role of racking has been gaining prominence relative to that of modules. As the relative importance of costs of PV racking has been marginal historically, there has been relatively little progress on reducing the materials and costs associated with it, which has caused racking to contribute to a significant portion of costs of entire PV systems. In order to overcome this challenge this study investigates a novel low-weight PV racking system for commercial rooftops based on crossed cables (X-wires) and compares it to racking systems already available on the market on capital costs, labor costs for installation, and technical specifications such as adaptability and power packing factor. The results of over 80% cost reduction and 33% increase in power density are presented and conclusions are drawn about the potential for tension-based racking systems to further reduce total PV systems costs on commercial flat roof tops resulting in LCOE savings of $0.01-$0.02/kWh.

  • Focus on module cost reduction overshadows racking improvements (until now)
  • First time paper on cost analysis of pv racking
  • Design related to previous paper (3D printed + wire)
  • 80% savings, increase of 33% power density; savings $0.01-$0.02/kWh
  • potential PV rooftop installs hindered by over-designed racking & costs.
  • cost analysis of design from X-wires design found in "3-D printing solar photovoltaic racking in developing world" paper above

Design of Post-Consumer Modification of Standard Solar Modules to Form Large-Area Building-Integrated Photovoltaic Roof Slates[edit]

Abstract: Building-integrated photovoltaic (BIPV) systems have improved aesthetics but generally cost far more than conventional PV systems because of small manufacturing scale. Thus, in the short and medium term, there is a need for a BIPV mounting system that utilizes conventional modules. Such a design is provided here with a novel modification of conventional photovoltaic (PV) modules to allow them to act as BIPV roofing slates. The open-source designs for the mechanical components necessary to provide the post-consumer conversion for a conventional PV module are provided, and prototypes are fabricated and installed on a mock roof system along with control modules mounted conventionally. The approximately U.S.$22/module BIPV roof-mounted system is direct mounted on the roof to eliminate the need for roofing shingles or other coverings, which effectively provides a 20% total cost reduction from conventional racking systems that demand a roof to mount upon without considering the savings from the rack itself. The results of the outdoor system testing found no water leaks. An increased operating temperature was observed, which would reduce the output from a silicon-based PV module by less than 10%. The results found significant potential for this design to further reduce total PV systems costs.

  • PV modules drop US $0.50/W [1,2], LC pv electricity 6 cents/kWh [3]
  • This design is USD22/module = 20% savings (vs conventional racking; 90% vs BIPV)
  • Financing increasing accesibility [7–12].
  • Some HOA ban PV [22]
  • Smart BIPV expensive; design uses conventional module instead
  • Avg op temp PV 50c; STC 25c; BIPV temp increase observed -sensor location
  • See losses based on racking system, cooling/airflow (<10% reduced output in this case)
  • open-source design of post-consumer modification of standard solar modules to form large-area BIPV.
  • SMEs & mfg
  • Data can be used life cycle cost analysis -need cost of materials and time of assembly/install.

Distributed manufacturing with 3-D printing: a case study of recreational vehicle solar photovoltaic mounting systems[edit]

Abstract: For the first time, low-cost open-source 3-D printing provides the potential for distributed manufacturing at the household scale of customized, high-value, and complex products. To explore the potential of this type of ultra-distributed manufacturing, which has been shown to reduce environmental impact compared to conventional manufacturing, this paper presents a case study of a 3-D printable parametric design for recreational vehicle (RV) solar photovoltaic (PV) racking systems. The design is a four-corner mounting device with the ability to customize the tilt angle and height of the standoff. This enables performance optimization of the PV system for a given latitude, which is variable as RVs are geographically mobile. The open-source 3-D printable designs are fabricated and analyzed for print time, print electricity consumption, mechanical properties, and economic costs. The preliminary results show distributed manufacturing of the case study product results in an order of magnitude reduction in economic cost for equivalent products. In addition, these cost savings are maintained while improving the functionality of the racking system. The additional electrical output for a case study RV PV system with improved tilt angle functionality in three representative locations in the U.S. was found to be on average over 20% higher than that for conventional mass-manufactured racking systems. The preliminary results make it clear that distributed manufacturing - even at the household level - with open-source 3-D printers is technically viable and economically beneficial. Further research is needed to expand the results of this preliminary study to other types of products.

  • Transport major portion of env impact. Sources: (Zhu and Sarkis 2006; Pearce et al 2007; Cholette and Venkat 2009; Meisterling et al. 2009; Winnebeck 2011)
  • 3D printers as environmentally sustainable due to this. Cites (Kreiger and Pearce 2013a, b)
  • Terminology Open-Source self-replicating rapid prototypers (RepRap)
  • Explains RepRaps
  • Open-source approach to PV (Buitenhuis and Pearce 2012)
  • Many PV on thingverse (Makerbot Thingverse 2012a, b, 2013a)
  • Cost per watt dropped 80% in past 5 years (Barbose et al 2012)
  • 3d printed plastic as opposed to aluminum on RVs.
  • Benefit of angle customization for RV (Lewis 2987; Shu et al 2006; Calabro 2009; Mehleri et al 2010)
  • Aluminum expensive (Renvu 2014)
  • Paper summary: novel 3d printable design with angle adjustment tested in 3 locations.
  • Methods starts discussing where stress occurs due to a bending moment
  • Goes through calculation of this to derive design parameters
  • Chose ABS plastic to resist environmental effects (Davis et al 2004)
  • Printed parts can be treated with acetone
  • Relative cost of racking inv. Proportional to PV size p.4
  • Pearce 2002 on the intrinsic sustainability of PV
  • King et al. 2014 on solar powered reprap
  • Results: traditional aluminum total $75.23 total, 37.6 c/watt (Northern Arizona Wind & Sun 2014)
  • 3D-Printed $7.21 total, 3.6 c/watt
  • Added benefit of tilt-ability
  • Added benefit of making system smaller
  • Studies needed for longevity
  • Not taken into account: RepRap unit and human labor.
  • Assumption that reprap already owned personally for other household products
  • Assumption that downloading stl file and using open source software is easy to use and user can walk away during printing
  • Further study needed for LCA

PV Cell Technology, Tests, Design[edit]

Advances in Solar Photovoltaic Technology: An Applications Perspective[edit]

Abstract: Advances in photovoltaic module technology, inverters, system installation practices, and design standards are improving the performance of PV systems and have led to PV becoming established as a strongly competitive energy source for off-grid energy applications. PV is also on the cusp of becoming competitive in grid connected configurations and is currently experiencing strong growth in this type of application. Substantially reduced PV module cost and higher module efficiency compared to products of just a decade ago are playing a key role in this expansion. The introduction of modern inverters that are more efficient, have higher reliability, and improved utility system interface features are also facilitating market growth. In addition, experience gained from hundreds of thousands of PV installations over the past decade, as well as a maturing base of PV service providers, system integrators, and new industry design standards has led to improved designs and economies in the installation of PV systems. Overall, PV energy costs have fallen by a factor of about 2 over the past decade and the prospects for continued improvement are strong. This presentation reviews advances in PV technology and the role they are playing in its expansion.

  • 15-40%/decade growth of PV usage globally @ 20-40 cents/kw-hr (1,2)
  • Module cost = 25-50% of total cost
  • Module density affects cost via BOS
  • Increased cell efficiency (better PV technology) = <modules, <BOS (i.e. racking, installation, amplification accessories etc.)
  • Racking adv: non- penetrating roof retrofit, labor free install, wind resistant & PV as multiple use (i.e. shade, BIPV) + 2ndary benefits (i.e. HVAC costs).
  • Fed & state sponsored wind loading testing
  • Table: value of PV advancements as reduction in “effective cost”
  • $2.5-6/W cost of pv module + 6-12 with install at time of paper (2004)
  • Lowering cost not dependent only on PV cell adv.

Dynamic thermal model of solar PV systems under varying climatic conditions[edit]

  • Electrical performance depends on temperature and thus climate (Nagae et al., 2006)
  • Temp inv proportional to output voltage => produced power (Skoplaki et al., 2008)
  • Previous studies model temp based on env (Schott, 1985; Servant, 1985; Malik and Damit, 2003; Nordmann and Clavadetscher, 2003; Krauter, 2004; Franghiadakis and Tzanetakis, 2006; Mattiei et al., 2006; Chenni et al., 2007; Durisch et al., 2007, and Topic et al., 2007)
  • These assume steady state
  • Can’t assume this during rapid fluctuation of irradiance (Jones and Underwood, 2001)
  • Must take into account thermal mass of unit
  • Paper extends previous thermal mass modeling work (Jones and Underwood, 2001; Notton et al., 2005; Mattiei et al., 2006; Balog et al., 2009; Armstrong and Hurley, 2010; Caluianu and Ba˘lta˘re_u, 2012, and Tsai and Tsai, 2012)
  • Summary: paper presents dynamic thermal model of heat transfer mechanism and validated with experimental data from Tampere, Finland (Torres Lobera and Valkealahti, 2012)
  • Displays energy balance equation (solar radiation in – power output – heat loss – time derivative of temperature times specific heat =0)
  • Provides expressions for variables
  • Specific heat of module is derived as sum depending on dimensions, density, and material of component parts
  • Goes through more thermos derivation
  • End of section 2 results in a time varying equation without analytical solution
  • Analysis used three winter days and three summer days
  • Discusses model results. Better agreement in winter than in summer-states more variability in summer.
  • Also mentions heating of the back of the module at different times of day and not being measured separately increasing error of measurement
  • Then goes into sensitivity analysis

A simple correlation for the operating temperature of photovoltaic modules of arbitrary mounting[edit]

Abstract: Following a brief discussion regarding the operating temperature of commercial grade silicon photovoltaic (PV) cells/modules and its effect upon the performance of free-standing one-sun PV installations, a simple semi-empirical explicit correlation for PV cell temperature and the corresponding efficiency form are proposed for modules of arbitrary mounting. To this end, a dimensionless mounting parameter, o, is introduced rendering the correlations suitable for systems like building-integrated photovoltaic (BIPV) array generators. The implications of ignoring radiation and free-convection are quantified and a comparison is made with analogous relations in the literature.

  • Temperature affects operation by affecting electrical parameters (voltage and current)
  • Temperature depends on angle of incidence
  • Derives expression for efficiency as a function of temperature compared to a reference temperature and efficiency
  • To lower temperature modules are designed to transport heat away from the panel, including through the mounting frame
  • At steady state this just transports heat to surface to release as convection and radiation
  • Derives equation for operating temperature based on thermal and physical properties, solar source and weather, and wind heat transfer
  • Develops a model with assumption that both sides of module experience same ambient temperature which is based on assumption of free standing module and not BIPV
  • Highly dependent on module area and angle of incidence, thus rigorous tests should be done to determine NOCT (Nominal Operating Cell Temperature)
  • Decision of proper velocity affects the operating temperature of the module
  • Convection must be taken into account as well

Investigation of the energy output from PV racks based on using different tracking systems in Amman-Jordan[edit]

Abstract: Solar energy is the promising renewable energy candidate in Jordan to cover the energy needs and to replace the traditional production ways of energy. The average solar radiation in Jordan is in between 4 and 8 KWh/m2 which make Jordan is a suitable location for solar investment. For that studying the possible ways to maximize solar energy production from the PV system is essential. This study comes to compare the outputs of solar panel racks driven by the horizontal single-axis tracker (HSAT), the vertical single-axis tracker (VSAT), and the altazimuth dual-axis trackers (AADAT), as well as that of a fixed solar panel rack.

  • Study compares horizontal single-axis tracker (HSAT), vertical single-axis tracker (VSAT), and altazimuth dual-axis tracker (AADAT)
  • P3 “…capacity of XX…”
  • Uses Energy-3D simulation to analyze different tracking methods
  • Derives tilt angle expression
  • Compares fixed panel to various tracking methods and to each other
  • incomplete study/paper

Performance Comparison of a BIPV Roofing Tile System in Two Mounting Configurations[edit]

Abstract: This paper examines the performance of a building integrated photovoltaic (BIPV) roofing system commonly available to residential markets. In particular polycrystalline Si PV roofing tiles were integrated with concrete roofing tiles in two mounting configurations being used by roofing contractors. In the first configuration the tiles were directly mounted to the roof sheeting allowing little to no airflow under the PV modules. In the second configuration furring strips were attached to the roof deck to create a counter-batten system to which the roofing and PV tiles mount. This counter-batten system provides an air gap between the roof deck and the PV/concrete tiles which allows for convective cooling. A complete data acquisition system was applied to both mounting configurations and they were monitored for a summer period in Golden, Colorado. A performance comparison is presented for the systems while both are gauged against freestanding rack-mounted polycrystalline Si PV modules. As expected, modules mounted directly to the deck operated at higher temperatures and produced less power than those on a counter-batten system while both systems operated at higher temperatures than rack mounted modules.

A Proposed Method of Photovoltaic Solar Array Configuration Under Different Partial Shadow Conditions[edit]

Abstract: The benefit of improving the efficiency of photovoltaic (PV) solar system has come into view because of increasing the demand for electricity, especially in the urban areas. However, these PV solar systems are vulnerable to the mismatch operating conditions. Under such conditions, the performance of solar cells has decreased rapidly since the nonuniform insolation hitting the cells and with different values. Then this leads to cause rapidly decreasing in the output power value and maximum power point, beside to hot spot points that may be occurring in the solar cell which finally leads to damage these cells. This paper proposes an optimal connection of substrings with different value of shadow conditions, based on a thorough configuration that can significantly reduce that nonuniform condition loss. The refinement over existing photovoltaic (PV) solar array interconnections is proven by extensive simulation results by using MATLAB SIMULINK. doi:10.4028/www.scientific.net/AMR.983.307.


Optimal Hybrid Array Configuration Scheme to Reduce Mismatch Losses of Photovoltaic System[edit]

Abstract: This paper proposes a hybrid array configuration technique to reduce mismatch losses in the photovoltaic (PV) array under partial shading condition. The reduction in PV array output power does not depend linearly on the shaded PV module, instead it is highly dependent on the extent of mismatch. The extend of mismatch depends upon several factors like type of configuration, array size and shading patterns. Here, different array configuration techniques like series-parallel (SP), total-cross-tied (TCT), bridge-linked (BL), honey-Comb (HC) along with a new hybrid array configuration technique have been discussed to contemplate the effects of mismatch conditions. A comparative analysis is being accomplished using different irradiance test conditions for determining the configuration having lowest amenability to power loss under mismatch condition. doi:10.1109/ICECCT.2017.8117990.

Optimal Configuration for Design of Stand-Alone PV System[edit]

Abstract: This paper presents a design for a stand-alone photovoltaic (PV) system to provide the required electricity for a single residential household in rural area in Jordan. The complete design steps for the suggested household loads are carried out. Site radiation data and the electrical load data of a typical household in the considered site are taken into account during the design steps. The reliability of the system is quantified by the loss of load probability. A computer program is developed to simulate the PV system behavior and to numerically find an optimal combination of PV array and battery bank for the design of stand-alone photovoltaic systems in terms of reliability and costs. The program calculates life cycle cost and annualized unit electrical cost. Simulations results showed that a value of loss of load probability LLP can be met by several combinations of PV array and battery storage. The method developed here uniquely determines the optimum configuration that meets the load demand with the minimum cost. The difference between the costs of these combinations is very large. The optimal unit electrical cost of 1 kWh for LLP = 0.049 is $0.293; while for LLP 0.0027 it is $0.402. The results of the study encouraged the use of the PV systems to electrify the remote sites in Jordan. doi:10.4236/sgre.2012.32020

Best practices for commercial roof-mounted photovoltaic system installation [2][edit]

  • Structural Loading
  • Wind loads
  • Hail
  • Snow
  • Debris accumulation
  • Seismic
  • Fire Hazards
  • Electrical Hazards
  • Weather-Related
  • Best Practices
  • Hazard Gap Analysis

Wind Loads & Tests[edit]

Wind Design Practice and Recommendations for Solar Arrays on Low-Slope Roofs[edit]

Abstract: Currently, ASCE standards do not provide specific guidance on wind loads for solar arrays of photovoltaic panels, in terms of either prescriptive design or requirements for wind tunnel testing. Guidance is needed, particularly for arrays of low-profile tilted panels on flat or low-slope roofs, because they are markedly different aerodynamically from structures currently addressed in the building code. This paper presents recommendations for the structural design of these solar arrays for wind-loading. Recommendations include (1) categorizing solar array support-systems according to their height above the building roof and how they distribute forces to the roof, (2) developing pressure coefficients that are applicable to structurally interconnected roof-bearing support systems, (3) considering load cases that include uniform wind pressure on the array and nonuniform (gust) patterns, (4) determining appropriate stiffness and boundary conditions for structural analysis, and (5) use of testing to verify behavior and calibrate analytical models. DOI: 10.1061/(ASCE)ST.1943-541X.0000806

Wind Loads on Low-Profile, Tilted, Solar Arrays Placed on Large, Flat, Low-Rise Building Roofs[edit]

Abstract: The author examined wind loads on low-profile, roof-mounted solar arrays, placed on large, low-rise buildings with nearly flat roofs by using scale models in a boundary layer wind tunnel. The author also examined the effects of building size and array geometry on enveloping curves of area-averaged pressure coefficients, typical of use for design. It was found that wind loads on the array increase with building size; normalizing the effective wind area by the building wall size leads to enveloping curves that collapse onto a single curve for each array geometry. For tilt angles less than 10°, there is an approximate linear increase in the pressure coefficients as the tilt angle increases. For arrays with tilt angles of 10° or more, the wind loads do not depend significantly on the tilt angle and are relatively constant. Roof zones for wind loads on solar arrays are larger than roof zones for bare roofs and depend on the array tilt angle. DOI: 10.1061/(ASCE)ST.1943-541X.0000825

Use of the Wind Tunnel Test Method for Obtaining Design Wind Loads on Roof-Mounted Solar Arrays[edit]

Abstract: ASCE 7 does not provide design wind loads for roof-mounted solar panels. This paper discusses the use of the wind tunnel test method, called Method 3 in ASCE 7-05, which was originally intended for obtaining design wind loads for individual buildings. Because roof-mounted solar arrays are generally mounted in many configurations on many buildings of many different shapes, additional requirements are necessary to use Method 3 in this situation. The paper describes these additional requirements. DOI: 10.1061/(ASCE)ST.1943-541X.0000654

Wind loading characteristics of solar arrays mounted on flat roofs[edit]

Abstract: With the increasing use of solar photovoltaics, wind-induced loads on rooftop solar arrays have become a problem. A series of wind tunnel experiments have been performed to evaluate wind loads on solar panels on flat roofs, mainly focusing on module forces calculated from area-averaged net pressures on solar modules of a standard size. In order to investigate the module force characteristics at different locations on the roof, solar array models, which were fabricated with pressure taps installed as densely as possible, were moved from place to place. Design parameters including tilt angle and distance between arrays, and building parameters including building depth and parapet height, have also been considered. The results show that unfavorable negative module force coefficients for single-array cases are much larger than those for multi-array cases; tilt angle and distance between arrays increase negative module forces; effects of building depth and parapet height on negative module forces are not obvious; and recommendation values in JIS C 8955 Standard correctly estimate negative mean module force coefficients but not peak values. https://doi.org/10.1016/j.jweia.2013.08.014Get rights and content

Wind Turbulence and Load Sharing Effects on Ballasted Roof-Top Solar Arrays[edit]

Abstract: This collection contains 106 papers presented at the ATC & SEI Conference on Advances in Hurricane Engineering, held in Miami, Florida, October 24-26, 2012. When Hurricane Andrew wreaked havoc on South Florida and Louisiana 20 years ago, the engineering community learned a great deal about how powerful storms affect the built environment. These papers demonstrate the application of lessons learned to reduce losses from subsequent hurricanes and to make communities more resilient to natural hazards.

Aerodynamics of Ground-Mounted Solar Panels: Test Model Scale Effects [3][edit]

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 [4][edit]

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 [5][edit]

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

Mechanics & Materials[edit]

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

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 [6][edit]

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 [7][edit]

System for scenario planning and forecasting world prices for steel and metallurgical raw materials [8][edit]

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.


Sustainable Applications[edit]

Photovoltaics — a path to sustainable futures[edit]

Abstract: As both population and energy use per capita increase, modern society is approaching physical limits to its continued fossil fuel consumption. The immediate limits are set by the planet’s ability to adapt to a changing atmospheric chemical composition, not the availability of resources. In order for a future society to be sustainable while operating at or above our current standard of living a shift away from carbon based energy sources must occur. An overview of the current state of active solar (photovoltaic, PV) energy technology is provided here to outline a partial solution for the environmental problems caused by accelerating global energy expenditure. The technical, social, and economic benefits and limitations of PV technologies to provide electricity in both off-grid and on-grid applications is critically analyzed in the context of this shift in energy sources. It is shown that PV electrical production is a technologically feasible, economically viable, environmentally benign, sustainable, and socially equitable solution to society’s future energy requirements.

Solar Energy for Rural Madagascar Schools: A Pilot Implementation by University of Nebraska Engineers Without Borders-USA[edit]

Abstract:A pilot photovoltaic system was constructed in Kianjavato, Madagascar by a team from the University of Nebraska Engineers Without Borders-USA Student Chapter. This project represents an integrated approach to energy supply, education and natural resource conservation. The system supplies power to ten 13 W fluorescent tubes in a primary school classroom for the purpose of extending public school hours into the evening for adult education. The project was implemented in partnership with a Malagasy non-governmental organization, the Madagascar Biodiversity Partnership. Future monitoring data will determine the outcome of the project and aid in the design of additional installations in the community.

Photovoltaic Panels On Greened Roofs -Positive Interaction Between Two Elements Of Sustainable Architecture[edit]

Abstract: The cultural center “UFA-Fabrik” in Berlin-Tempelhof has been known for years for its use of ecological technology. The original structures were completely renovated in 1984 and fitted with greened roofs at that time. Today the entire complex includes ca. 4,000 m2 of greened roofs. Since 1992 a monitoring program has tracked development of the vegetation, microclimate and retention of precipitation. The first solar panels were installed on the UFA Factory in 1998. A year later, an array consisting of ten 2 kWp photovoltaic panels was added on a greened roof. One part of the monitoring includes tracking the efficiency of fixed versus steered panels; another regards the interaction between the greened roof and the photovoltaic panels. While this is a preliminary report, several tendencies seem clear: the tracked solar panels are generating ca. 10 – 15% more electricity than the fixed ones. The greened roof is notably cooler than conventional bituminous roofs: While lower temperatures lead to higher voltages at silicon based photovoltaic panels, the electricity generation of PV on green roof is higher than on conventional roofs. We are in the process of quantifying that fact. Due to construction activity accompanying the installation of the array it was difficult to evaluate the vegetation during the first year; however, from the second year on investigation of the vegetation under the panel indicates significantly improved growth of the species relative to plant height and foliage density. There also appears to be a change in species from small plants (e.g. Sedum) toward larger ones such as Artemisia.

  • PV power gen higher on green roof (op. temp.) + increased plant growth (shade)
  • Higher temp on conventional roof


Economics, Finance, Policy[edit]

Toward cost-effective solar energy use[edit]

Abstract: At present, solar energy conversion technologies face cost and scalability hurdles in the technologies required for a complete energy system. To provide a truly widespread primary energy source, solar energy must be captured, converted, and stored in a cost-effective fashion. New developments in nanotechnology, biotechnology, and the materials and physical sciences may enable step-change approaches to cost-effective, globally scalable systems for solar energy use.

Tracking the Sun VI: An Historical Summary of the Installed Price of Photovoltaics in the United States from 1998 to 2012[edit]

A review of solar photovoltaic levelized cost of electricity[edit]

Description: As the solar photovoltaic (PV) matures, the economic feasibility of PV projects is increasingly being evaluated using the levelized cost of electricity (LCOE) generation in order to be compared to other electricity generation technologies. Unfortunately, there is lack of clarity of reporting assumptions, justifications and degree of completeness in LCOE calculations, which produces widely varying and contradictory results. This paper reviews the methodology of properly calculating the LCOE for solar PV, correcting the misconceptions made in the assumptions found throughout the literature. Then a template is provided for better reporting of LCOE results for PV needed to influence policy mandates or make invest decisions. A numerical example is provided with variable ranges to test sensitivity, allowing for conclusions to be drawn on the most important variables. Grid parity is considered when the LCOE of solar PV is comparable with grid electrical prices of conventional technologies and is the industry target for cost-effectiveness. Given the state of the art in the technology and favourable financing terms it is clear that PV has already obtained grid parity in specific locations and as installed costs continue to decline, grid electricity prices continue to escalate, and industry experience increases, PV will become an increasingly economically advantageous source of electricity over expanding geographical regions.

Peer-to-peer financing mechanisms to accelerate renewable energy deployment[edit]

Future Global Energy Prosperity: The Terawatt Challenge[edit]

Description: Innovations in nanotechnology and other advances in materials science would make it possible to transform our vision of plentiful, low-cost energy into a reality. By developing new technologies, marshaling the excellent resources of organizations like the Materials Research Society, and developing the talents of a new generation of scientists and engineers, I believe that we can solve even our most critical energy problems.

EIA: Annual Energy Outlook Through 2040[edit]

Description: The share of U.S. energy produc tion from crude oil and lease condensate is shown to rise from 19% in 2013 to 25% in 2040 in the high oil and gas resource case, as compared with no change in the reference case. Dry natural gas production remains the largest contributor to total U.S. energy production through 2040 in all the AEO2015 cases, with a higher share in the high oil and gas resource case (38%) than in the reference case (34%) and all other cases.

A new approach to scheduling in manufacturing for power consumption and carbon footprint reduction[edit]

Description: Manufacturing scheduling strategies have historically emphasized cycle time; in almost all cases, energy and environmental factors have not been considered in scheduling. This paper presents a new mathematical programming model of the flow shop scheduling problem that considers peak power load, energy consumption, and associated carbon footprint in addition to cycle time. The new model is demonstrated using a simple case study: a flow shop where two machines are employed to produce a variety of parts. In addition to the processing order of the jobs, the proposed scheduling problem considers the operation speed as an independent variable, which can be changed to affect the peak load and energy consumption. Even with a single objective, finding an optimal schedule is notoriously difficult, so directly applying commercial software to this multi-objective scheduling problem requires significant computation time. This paper calls for the development of more specialized algorithms for this new scheduling problem and examines computationally tractable approaches for finding near-optimal schedules.

Future Global Energy Prosperity: The Terawatt Challenge[edit]

Description: Innovations in nanotechnology and other advances in materials science would make it possible to transform our vision of plentiful, low-cost energy into a reality. By developing new technologies, marshaling the excellent resources of organizations like the Materials Research Society, and developing the talents of a new generation of scientists and engineers, I believe that we can solve even our most critical energy problems.

Rooftop solar power: The solar energy potential of commercial building rooftops in the USA[edit]

Description: United States commercial building rooftops may be the most wasted real estate in North America. Combined, these predominantly flat rooftops represent an area of more than 1,000 square miles that, outside of their sheltering function, do nothing more than soak up the sun, literally. More than half of this space has the potential to produce energy using simple photovoltaic, or solar electric, generating stations. Bill Jeppesen, for RWE SCHOTT Solar, Inc., USA reports.

Discussion of strategies for mounting photovoltaic arrays on rooftops [9][edit]

Abstract: The mechanical attachment of photovoltaic (PV) arrays to rooftops presents a number of unique and challenging issues for system designers and installers. With a resurgence of roof-mounted PV installations due to increasing duel costs and decreasing PV system prices, the Florida Solar Energy Center (FSEC) has accelerated its investigations of array mounting strategies, with the objectives of identifying key performance and cost parameters from a systems engineering perspective. Two principal classifications can be defined for rooftop PV array mounting systems: building-integrated (BIPV) and building-attached (BAPV) or standoff designs. The various attachment methods within these categories each have pros and cons that affect the labor and cost associated with the install and the system performance. An overview and assessment of some existing rooftop PV array attachment methods or mounting approaches, and their advantages and disadvantages with respect to key design criteria are presented to assist designers and installers in the selection of the appropriate method for a given project.

  • Rooftop PV mounting review & recommendations re: design
  • Considerations: Thermal & e performance, install & maint, circuitry & connectivity, orientation etc.

-BIPV & BAPV (standoff) -for design factors see Barkazi, 1998 -11 design factors provided to det. appropriate attch method

  • sm mods/sys = greater # of connections & hardware
  • 5% decrease / 10degC increase temp coeff

-design & air flow

  • BIPV temp coeff 50degC/kWm^2 vs standoff @ 15-30 (King, 1997)

-heat transfer (Barkaszl, 1998) -6" to 3" standoff height

  • loading on rooftop: dead loads (5-10psf, 110-120mph winds)

-mount to truss, rafter purlin, join vs. deck

  • penetrations and sealing -UV res butyl rubber, caulk, vs. flash/boot (Dunlop et al, 1999)
  • FG shingles <20 years vs. PV>20 (=re-roof)
  • material -corssion (humidity, coastal salty air, diff metal & concrete contact)

-ss 316, 403, al 6061, 6063

  • lacking citations


References[edit]

  1. Wittbrodt, Ben, and Pearce, Joshua M. “3-D Printing Solar Photovoltaic Racking in Developing World.” Energy for Sustainable Development, vol. 36, Elsevier Inc., Feb. 2017, pp. 1–5, doi:10.1016/j.esd.2016.08.001.
  2. Wills, Rosalie, et al. Best Practices for Commercial Roof-Mounted Photovoltaic System Installation . Springer, 2015.
  3. 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.
  4. 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.
  5. Aly, A.M., Bitsuamlak, G., n.d. Aerodynamic Loads on Solar Panels, in: Structures Congress 2013. https://doi.org/10.1061/9780784412848.137
  6. 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
  7. Galambos, T. V. Basic Steel Design with LRFD. Upper Saddle River, N.J: Prentice Hall, 1996.
  8. 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.
  9. S Barkaszi, J Dunlop, "Discussion of strategies for mounting photovoltaic arrays on rooftops", Solar Engineering, 2001