Please leave any comments on the Discussion page including additional resources/papers/links etc. Papers can be added to relevant sections if done in chronological order with all citation information and short synopsis or abstract. Thank You.

## Notes

• The first PV+Noise barrier (PVNB) system was installed in Switzerland in the year 1989. Major of the installations of such type of systems are in Europe majorly in Germany, Switzerland and Netherlands. Only 2 installations in China and Australia are located outside Europe.
• The types of module design can be classified as Retrofit and Integrated designs.
1. Top mounted
2. Shingles
3. Cassette
4. Horizontal Zig Zag
5. Bifacial

## Literature Review

This is the Literature Review Page for my project topic on PV+Noise barrier systems

## PV on Noise Barriers

The paper present the concept of PV modules mounted on noise barriers. The paper gives a short overview of the state of art and progress made in the use of PVNB in Europe. The paper also demonstrates the prototype of module designs of PVNB.

1. The mounting of PV modules on the noise barriers along the road and rails provides the benefits of dual use of built up land, energy generation in highly congested and high usage areas and easy access for construction and maintenance.
2. The different types of module design that have been implemented and tested for more than 2 years in Europe are:
• Cassette
• Zig Zag
• Shingles
• Bifacial
3. The cassette and Zig and zag module uses a combination of both sound reflection and sound absorption techniques. Also careful considerations are given to avoid shading effect in these type of designs.
4. The bifacial modules consists of solar cells on either side of the module design. Thus one side of the module gets exposed to the morning sun while the other side is exposed to the evening sun thereby increasing the energy output compared to a single side oriented PV module.

## Estimation of environmental benefits, cost benefits and system description of PVNB installed along a metro line in China

The paper presents the system description, environmental benefit evaluation and cost evaluation for PV+Noise barrier module installed along a urban metro line in China.

SYSTEM DESCRIPTION:

• The project is a PVNB installed along the metro transit infrastructure in Shanghai. The length of the section of transit line under consideration is 360m.
• Sound reflection properties of Noise barriers are achieved by using the solar cell modules itself.
• The angle between the direction normal to the path of barrier and south direction was 67º. Thus the orientation of the PV module was not ideal for mounting it. The modules were mounted in the vertical plane configration.
• Amorphous Silicon (a-Si) solar cells were considered due to their high light absorption rate. Easier and cheaper manufacturing process.
• The PV modules were grid connected using a DC junction box, Inverter and AC distribution box.
• The total no of PV modules used along the length is 223, out of which 216 are identical and remaining 7 are used to adjust the voltage output.
• Also in Shanghai due to dirt accumulation the PV output power is reduced by 10%.

FORECASTED ENERGY

• The energy forecast are based on the formulas presented in the book "Photovoltaic Solar Energy Generation" by A. Goetzberger V.U. Hoffmann and Klein and Theilacker model of solar radiation.
• The calculated values of total annual average radiation is 763.2 kWh/sq.m, peak hours of solar is 763.2. The annual energy output is of the order of 4274~5495 kWh. The capacity factor is of the order of 7.13% which is primarily due to the 67º orientation of PV modules from the polar south.

ENVIRONMENTAL BENEFITS

• The term EPBT (Energy Payback Time) is used to understand the overall benefits the PV system connected to grid brings to the environment. It is defined as,
EPBT = ENERGY(Invested) / ENERGY(PV)

• The typical value of EPBT calculated is 5.4 years, which is very small compared to the entire lifespan of the PV module system of 20-30 years.
• Also the cost savings in terms of pollution control costs is of the order of 455-1300$/kg of gas emission prevented. ## Photovoltaic Integration with tunnel shaped sound barriers The Paper talks about the Acoustic Photovoltaic panel for a tunnel shaped sound barrier system. Also the paper focuses on the Balance of system configurations. 1. Owing to the circular nature of the barriers the PV modules are mounted on a variable surface orientation. Thus the tilt angles for each parallel group of PV cells will be different. 2. The APV consists of the lower substrate which helps to reduce the sound propagation, while the PV module is mounted on top of it. Considerations have to be given to the heat dissipation of the PV modules so that overheating of the PV cells can be avoided. 3. The BOS for such type of PV module configration shall be capable to take care of the different modules mounted at different tilt angles. 4. One type is the one in which each APV is equipped with an independent inverter which can be directly be connected to the grid. Different surface orientation is not an issue since each panel is fitted with maximum power point trackers and are shunt connected on the AC side. Also safe operation and soft performance degradation is achieved. 5. An option for the 3 phase or single phase AC-APV panels, is the internal connection of the PV module with the inverter to form a 3 phase line. The output of the inverter can be either star connected for 3 phase AC or shunt connected for single phase AC. However, the major drawbacks of this system is the losses due to ac currents in the low voltage circuit and the inverter will not be easily accessible. ## Photovoltaic Noise Barrier in Canada The paper is a study about the potential of the PVNB systems for Canada. The Ontario province of Canada was considered to study the potential of PVNB. The paper also talks about the various PVNB designs, the noise barrier legislation and standards of Canada. • In the Ontario province of Canada, there are approximately a total of 15,000 kms of transportation network. However, the southern part of Ontario has a high concentration of roads and population which is a high potential for building Noise Barrier integrated PV. • Out of the total highway length of Ontario, 40-50 % are oriented in the East-West Direction, 25-35% in the North-South direction and 15-25% in the South-East,North-East,South-West or North-West orientation. • Thus major of the highways are best suited for the ideal South oriented PV panels. For highways that already have sound barriers, we can use the retro-fitting technologies of Shingles and Top mounted PVNB. For the N-S oriented roads, the bifacial PVNB technology can be used. • In Ontario, there are an existing 155kms of noise barriers constructed already and every year approximately 5kms are added. The sound barriers are majorly made up of concrete and the rest are constructed using wood or metal. For noise barriers located outside the city areas noise barriers with reflection properties can be used. Thus for sound reflection use, we can use standard PV modules wherein the transparent substrate acts as the reflecting component. • The annual solar irradiation in Ontario was estimated using the RETScreen model for PV projects. The results showed that the maximum average yearly irradiation of 1.55Mwh/sq.m-yr is received for a tilt angle of 30-45º. Also for the N-S oriented roads the maximum average yearly irradiation is around 1.4Mwh/sq.m-yr for a flat oriented PV Panel. • The maximum energy yield by using PVNB technology in existing noise barriers in Ontario was calculated to be around 20 GWh/yr. However, this value did not include an shadowing effects due to trees and other structure around the noise barrier. • One major reason for absence of PVNB technology in Canada is due to the high noise limit set at 55dB by the Govt. This is higher than the WHO standard of 45dB and European standard of around 40-49dB. Thus implementation of stringent rules will lead to addition of more PVNB technology in Canada. • Also for integration of PV and Noise barrier systems new standards are needed to be formulated since the existing noise barrier standards do not consider PV integrated noise barrier system. ## Integrated PV Noise Barriers: Six innovative 10kWp Testing Facilities a German/Swiss Technological and Economical success story The paper presents the monitoring results of 6 different types of PVNB modules installed in Germany and Switzerland. In terms of monitoring, the PV and noise damping properties of all the modules were compared using the same monitoring hardware. • PVNB GERMANY (A96 Highway Munich) Cassette Type- 9.9kWp 1. Highly integrated design and easily mountable. 2. The performance ratio which is measure of the PV modules energy output performance was measured. The values varied between 0.55 (July) and 0.79 (February). 3. The major reason for poor performance was due to inefficient heat dissipation. The module design caused the module operating temperature to reach 51.9° celsius in summer wheres the module temperature was about 30.9° celsius in February. 4. Also another reason for the performance index to be on the lower side was due to the self shading effects caused by the upper module on the lower module. 5. Another reason was the damage to the panels due to vandalism. • PVNB GERMANY Shingles Type- 9.1 kWp 1. The Shingles type design is a highly compact and retrofit design. Thus in this prototype design we can the energy output/metre of road is more. 2. The performance ratio varies between 0.59(January)-0.7(May). The average module operating temperature is moderate due to the air convection which helps to reduce the module temperatures. 3. However, this module also suffers from the self shading effects. The lower placed module outputs are reduced due to the shading effect of the upper modules. The maximum loss due to shading is about 4%. • PVNB GERMANY Zig-zag Type-10.08 kWp 1. In this type of design the PV modules are stacked in alternating planes of PV panels and noise absorbing surface. The design offers an aesthetic look. 2. The PV panels are however tilted at an angle of 75° against an optimum tilted angle of 35°. This affects the energy ouptut of the PV panels considerably. 3. Also, the installation of these modules takes a long time unless they are pre-fabricated in factory. 4. The performance index varies between 0.69 (july)- 0.79 (February). 5. Also the self shading effect is avoided due to the high inclination angle of the PV panels. • PVNB Switzerland(A1 Motorway) Type Bifacial- 10kWp 1. This is a patented design of TNC Germany. This prototype module design is favourable for roads oriented North-South. 2. The panels are placed vertically along the sides of the highway and it offers the highest level of integration possible in terms of PV and noise barrier capabilities.The PV module itself is the noise damping structure. 3. The PV Panels located on either side of the module helps to capture the suns irradiation from frontside(East) and backside(West). However the output on the backside is lower compared to the frontside. The performance ratio of the module varies between 0.69-0.56. • Noise Protection properties. 1. In order to understand the Noise protection offered by the different module design, the modules were tested as per ISO 10847, which deals with In-situ determination of insertion loss of outdoor noise barriers of all types. 2. Of the above mentioned module designs, the zig-zag and cassette type offer sound absorbing properties. The shingle and bifacial act as the sound reflecting modules. 3. The sound protection features of different type of modules can be summarized as below, Design Type Height of module Insertion Loss at 1.5m height(dB)** Insertion Loss at 5m height(dB)** Cassettes 3.2m 13.7 9.7 Shingles 3.0m 11.7 3.8 Zigzag 3.9 14.1 4.3 ** Insertion loss is measured 20 m behind the Noise barrier  ## COMBINING PHOTOVOLTAICS AND SOUND BARRIERS- A FEASIBILITY STUDY The paper talks about the economic and ecological feasibility of a Photovoltaic noise barrier. The hypothetical case study is of highway E313 in Tuilt region of Belgium. 1. PVNB is an alternative technique for space constraint PV structures. 2. The cost benefit analysis of the PVNB system were evaluated based on the net present value, internal rate of return, payback period and discounted payback period. Also the ecological benefits was expressed in terms of monetary gains. The economic and ecological benefit of PV structure and noise barrier were evaluated together and separately. 3. The Solar panel assessment The cost benefit analysis of the Solar panel showed that the panels are profitable with an IRR of 8.07%. Also the payback period of the system is around 9.7 years. The benefits of reduced CO2 in terms of monetary gains is small but is important to gain green current certificate which majorly affects the profitability of the PV Panels. 1. Noise Barrier Assessment The noise barrier only has ecological benefits to it. To calculate the monetary value of the ecological benefits from the noise barrier, stated preference and revealed preference of the customers was used. In stated preference the amount of money that any customer was willing to pay to change the quality of noise environment around them was used to calculate the monetary gain. In revealed preference, customer behaviour is observed using data on housing price and noise loads. By using the Hedonic pricing method the degree of how much people are willing to pay more can be evaluated. The results of Hedonic pricing can be described in terms of noise sensitivity depreciation index (NSDI) which is the house price drop per db increase in sound level.The noise barrier for a 25 year lifetime has a chance of being profitable. Also a significant amount of investment on the noise barrier can be recovered by the ecological benefits of reduced noise nuisance. 1. PVNB Assessment: The PVNB as a whole is profitable with an IRR of 5.67% and payback period of 12 years. However the major factor influencing the profitability is the presence of Green Current Certificates and government subsidy on solar projects. ## PV Soundless – Keeping the world record "along the highway" – Performance gain by repowering part of a 718 kW PV sound barrier after 6 years of operation. The paper talks about the different types of PV+Noise barrier system installed in the Freising area near Munich airport. The paper focusses on the performance analysis of different types of PV sub systems. • Sub system 1: PV modules with independent sound barriers • Sub system 2: Ceramic PV module with integrated noise barrier • Sub system 3: Restructured Glass Ceramic PV module with integrated noise barrier The subsystem 1 was installed in the year 2002, where PV panels were placed on top of the noise barrier. The subsystem-2 utilised a new ceramic based PV module which had noise reduction capabilities. However, due to the discoloration of the ceramic PV modules, the PV modules were over built by using restructured glass. • PERFORMANCE ANALYSIS: The performance analysis of the above mentioned sub systems was carried out based on a 15 minute energy meter data from January 2009 - July 2010 was used. Also the inverter or PV string failure was not monitored continuously, it was detected only by analysing the AC power yield with no system failure and the daily AC power yield. The results showed that the sub system-3 performed better than both of the other system with this PV module performance better than subsystem-1 and subsystem-2 by 5% and 20% respectively. Another major factor which affects the performance of the PV module is the inverter failure, all the subsystem it was observed that real time inverter level monitoring is essential to obtain optimum yield from PV modules. ## Quality issues for photovoltaic-sound barriers The paper provides an insight into the quality issues that needs to be taken into consideration while design of an integrated PV noise barrier system. Quality refers to not only the electrical and acoustical functionality of the PV sound barriers but also involves the safety, ease of maintenance and visual impacts. Definition of quality standards for PV sound barriers is important not only for system designers but also for end customer so that activities related to commissioning and acceptance tests can be done. The following quality parameters should be met while designing the PV sound barrier system 1. Properly sized and oriented 2. Minimum of shading effects from poles, stands or adjacent structures. 3. Compliant to applicable building and electrical codes. 4. Minimum electrical losses over wiring, switches and inverter. 5. Properly grounded. 6. Quality electrical output. Also during design of the PVNB system following considerations shall be taken care: • Architectural Design: The PV modules should be naturally integrated into the Sound barrier shape. Also the design of the PVNB system should be flexible and adaptable with a pleasing aesthetic value. • Functionality: The PVNB design must meet the requirements of both sound abatement and solar energy conversion. Due to the complexity of different stakeholders like PV engineers, Acoustic specialist, Government agencies, road/railway management agencies proper guidelines shall be laid down to check the working of the PVNB system as a whole. At present the PV array and noise barrier on site testing is done separately as per IEC-61829 and EN-1973 standards respectively.#Photovoltaic Performance: The tilt angle of the PV array shall be optimum enough to avoid soil accumulation and structural needs for noise abatement. A good thermal design helps to lower the PV operating temperature thereby increasing its output. There should be a good matching between the inverter input operating range and fluctuations of the PV array output due to temperature or irradiation variability. • Acoustic Performance: PV panels consisting of glass or plexiglass sheets tend to have intrinsic sound reflection properties. Thus the integrated design should be carefully designed to avoid slits, acoustic short circuits and resonance at acoustic frequencies. • Safety: The safety of the PVNB system should be designed in terms of car crash and fire propagation. Also the PVNB system should be free from any falling barrier segments and should be designed to withstand any stone hit from cars or vandals. The PVNB should be designed with safe and easy access for the operator. Also special care should be taken while orienting the PV panels so that glare to drivers can be avoided. • Duarability: The mechanical structures should be well designed to withstand any worst environmental conditions like wind, rain, and snow. The panels shall be able to withstand any environmental conditions like corrosion, pollution and soiling. • Maintainability The reliability of the system also depends upon the maintenance of the system. The PV Panels have a warranted lifetime of about 25-30 years. However, the inverters have a life cycle of 3-4 years, thus periodic maintenance of the PV system should be carried out. Also optimum operation of the PVNB system can be achieved by continuous monitoring of the PV array, Inverter and Balance of system components. ## Assessment of PVNB in Italy In this paper the potential of PVNB for Italian national roads has been carried out. The paper uses GIS method to evaluate the potential PV energy. The estimation of extent of roads that can be used to implement the PVNB system is done by using a set of algorithms on the basis of traffic flows, meteorological conditions, global radiation and the surrounding environment. • Traffic Simulation The transportation system was simulated by using the numerical transport model applied to the road links and road intersections. With this model the major traveller origins and destinations were identified. • Acoustic Model The acoustic model based on the French model NMPB was used to predict the noise polluted areas. The model helps to evaluate the equivalent continuous level of power/metre at receiver's position based on the acoustic power of light vehicle, percentage of heavy vehicles, speed of vehicle streams and no of vehicles per hour. The paper studied the 3 main road topologies of single and dual road carriageways with double flow and each flow direction. The model helped to determine the extent of noise polluted areas from the edge of the roads which in turn helped to determine the length of the noise barrier system. • GIS model The GIS model was used to estimate the irradiation levels in different acoustically polluted areas. Special consideration was given to exclude the shadow areas. The irradiation level was calculated using the Hillshade method applied to digital terrain model with step size of 250m was used. In cells where the direct and diffused irradiation was less than 50% was then discarded. Also the intersection of the roads and square cells was used to determine locations favourable for PVNB installation. • PV potential estimate The estimate of the potential PV energy was based on the horizontal radiation data published by the ENEA. Also the effects of the tilt angle and the azimuth angle on the radiation levels were taken into consideration and the yearly irradiation was plotted as a function of tilt and azimuth angles to get the most optimum PV panel orientation. The study showed that the maximum irradiation was obtained for a 35° tilt and azimuth angle of 0°. Tilt angles less than 25° foster dust accumulation thereby reducing the PV panel yield. Azimuth angle of 90° which corresponds to North-South orientation is not suitable in terms of irradiation level. However, by using bifacial PV modules can be used to recover some of the PV potential. The results showed that for an assumed performance ratio of 70% the PVNB potential can be summarized as below Tilt Angle (degrees) Length (km) Installed PV capacity (MWp) Energy production (GWh/yr) 35 204 20 25 60 175 17 21 90 (bifacial) 20 2 2 ## PVNB Potential in Europe The paper talks about the potential of PVNB systems in Europe specifically in UK, Germany, Switzerland, Netherlands, Italy and France. However the results for these nations was extrapolated to the other EU members. The type of PVNB system was classified on the orientation of rail and road network. This orientation for rail and road network was divided for 1 by 1 geographical degree. The potential of PVNB was divided into following sections: • Theoretical Potential: The theoretical potential corresponds to applying PVNB to all existing and new rail and road projects without considering the shading effects. Thus the theoretical potential provides the upper boundary of the PVNB system in each of the countries. The results show that main potential is located in big metropolitan areas like London and Paris. Approx 65% of the annual production corresponds to road infrastructure and the remaining 35% corresponds to railways. • Technical Potential: The Technical potential corresponds to PVNB for rail and roads planned as of today. Also the existing NB will be upgraded with PV systems. Shading effects are considered and the NB orientations are done for each of 1 by 1 geographical degree. The technical potential results revealed a total of 584Mwp along roads and another 217 Mwp along rails. Germany and Netherlands have major potential. • Short Term Potential: The short term potential is for all the noise barriers planned as of today. The NB are classified into 1 by 1 geographical degrees. The short term potential showed that Switzerland, Germany and Netherlands had a major potential for PVNB system. The national policies in France, Italy and UK was not favourable due to poor Noise barrier planning. • Anticipated Potential: The anticipated potential is based on the analyses on the national basis on the economic competitiveness of PVNB system w.r.t other type of renewable energy and the political willigness of introduction of PV on Noise barriers. The anticipated potential showed good results for Germany and Switzerland who have been on the forefront for this type of system. Netherlands has a neutral approach towards PVNB due to large no of parties involved in erection of noise barrier, economic feasibility and accessibility of noise barrier in urban areas. In UK and Italy, the potential for PVNB is very low due to low usage of noise barriers along roads and railways and also due to the lack of incentives for PV electricity fed into the grid. France has a lower potential due to very low price incentive for PV generated electricity to grid and lack of technical know how about the PVNB system. The short term potential was further extrapolated for other European union countries by multiplying the length density with the average short term potential for other countries. The result showed that Spain among other countries had most potential for PVNB. ## 500kWp PV SOUND BARRIER WITH CERAMIC BASED PV MODULES The paper talks about the technical aspects of the world's largest 500kWp PV noise barrier system. It discusses about the novel implementation of the ceramic integrated PV with noise barrier. 1. ISOFOTON developed the ceramic PV module (I-50CER) which has both noise reduction and PV production capability. The major issue to develop the integrated PVNB was weight since for noise reduction purpose the minimum weight of the PV module should have been 25kg/sq.m. Thus the ceramic substrate was used for the PV cells. The ISOFOTON I-50CER module provided a noise attenuation level of 32dB. The panels for site mounting purposes was pre-assembled to aluminium frames. 2. The 500kWp PV system consisted of 2 PV fields: The ceramic based PV module of an installed power of 338 kWp and standard PV module with installed capacity of 162kWp. The array's were slightly curved and faced south with a tilt angle of 30 deg. The standard modules were located on the lower part backed by a structure of concrete which acted as the noise barrier. The ceramic modules were installed on top of the standard modules. Good ventilation was secured for both PV systems, for the standard system air was allowed to below the module row and exit along the structures carrying the PV modules. 3. To measure the performance of the individual PV modules types, the reference modules of each technology was placed side by side on top of the noise barrier. These reference modules had integrated temperature sensors. 4. Performance results for both the module type did not show significant difference. The short circuit characteristics for both the PV modules were identical. However, in terms of the temperature behavior the ceramic panels got warmer during the day with the max temperature difference between the two modules types was 5 kelvin. 5. Another thing observed during the performance of the 2 module types was that the AC performance of the standard module was symmetric around solar noon but for the ceramic module the performance ratio is higher before noon and lower in the afternoon. This characteristic was related to the back ventilation of the panels which was not equal. 6. The standard PV modules had a performance ratio of 0.7-0.75 while the ceramic PV module had a performance ratio of 0.71-0.76. Also the PV modules had the power degradation of 1.6% due to outdoor exposure. ## Power without Noise-PVNB potential under Australian conditions The paper reviews the European progress in PVNB technology designs and installations. The author presents an overview of the potential of this technology for Australian roads and climate. 1. The Australian geographical extent and variations in climatic characteristics, the type of PVNB module to be used depends upon the site location and its orientation. There is a difference in the irradiation incident on the planar surface at Cairns (Northern part of Australia) and Sydney (Southern Part of Australia). 2. The author analysed the shading effects for the shingle type design using the ECOTECT tool. The results showed that the lower shingle structures had shading issues during summer time. Also by proper positioning of the upper shingle layer, we can reduce the shading effects on the lower layer. 3. A rough figure estimate for different parts of Australia showed that Queensland had a total of 20km of noise barriers, Victoria will have 20-30 kms of noise barriers and sydney region will have close to 16 kms off noise barrier. These areas where potential areas where the PV modules could be installed as a retrofit or integrated design. ## The Bifacial North/South Concept and the Potential in Germany Nordmann, Th. and Götzberger, A. (1995) Motorway Sound Barriers: The Bifacial North/South concept and the Potential in Germany, 13th European Photovoltaic and Solar Energy Conference and Exhibition, 23rd-27th October 1995, Nice, France, p. 707-709 The paper presented the concept of bifacial PV technology as an alternative to the traditional South oriented PV modules. The panels were implemented for the North South oriented roads. The results showed that the panels were less immune to dust and their output performance degradation due to dust was negligible. The bifacial module yield was almost equal to the inclined southern optimally oriented panels. Finally the paper presents the PVNB potential in Germany by dividing the entire region into 63 grid squares and calculated the optimistic, technical and short term potential for the plant. ## The potential of PV along Dutch national highways and expressways The above document is the thesis report for the evaluation of the potential of the PVNB system for Dutch national highways and roads. The research was aimed at estimating the potential of the PVNB system by the year 2030. The basic points considered are the different possibilities of implementing this system, the area available for PV on noise barrier and the solar irradiance in these areas, electricity generated by these system, performance of the PV noise barrier and practical factors involved in implementing the PV noise barrier system. • Literature review: For PV energy to be cost effective and competitive with other energy sources, its price shall be competitive with other energy sources. However due to price dips in PV module prices, financial incentives and high local energy prices PV energy is competitive with other sources. Solar radiation is received on the earth's surface as direct, diffused and reflected irradiation. The following terms help to evaluate the irradiation level received on the earth's surface. Global Horizontal Irradiance(GHI): It expresses the irradiation that reaches a horizontal earth surface. It is further classified into Direct horizontal Irradiation (DHI) and Diffuse horizontal irradiation (DFI). Direct Normal Irradiance(DNI)- It is the irradiance received on the earth's surface normal to the direction of the sun. DNI= GHI x irradiation yield factor  The PV energy output can be defined as, P= G/1000 x A x nominal efficiency x PR  P= Power in watts G= Irradiance (w/sq.m) A= Area Nominal efficiency= Efficiency at STC. PR= Performance ratio The nominal efficiency is the efficiency offered by PV panels under standard temperature conditions. It is usually of the order of 20.4%. The performance ratio acoounts for the losses in the balance of system and other environmental conditions like temperature, shading and dust. As a conservative value we consider the PR to be 0.75. These factors should be considered while deciding the type of PV array to be used. In the market today we have the crystalline Silicon (C-Si) PV modules and the thin film technologies. The C-Si panels are bulky and need support frames. However, the thin film are quite flexible in nature. The PV energy around roads and highways can be independently used to power street lights, signage's, guide lights and reflectors. Also for large systems the energy generated can be transferred to the grid. This report talks of larger system and primarily about the PVNB technology. Netherlands has very limited land resources for large scale PV plants, thus the PVNB technology is very useful in Netherlands. Also the large road and rail network with densely populated regions provide a great potential for PVNB systems. • Methodology The Methodology involved steps to determine the potential of the PVNB system in Netherlands. In order to estimate the potential it was necessary to select appropriate study area and data. The study area was developing the road model and calculating the solar irradiation levels in different regions of the country. The data used was the extent, types, speed limits of roads and the noise barriers installed along the roads. To calculate the solar irradiance a digital elevation model was used, this model was inputted into the GIS software to calculate the irradiance levels in different parts of Netherlands In order to assess the suitability of any location for PVNB application, the roads were categorized into different orientations. Each orientation corresponds to an optimum irradiation yield factor and the type of system that can be installed. The irradiation levels were calculated by using the Solar Analyst tool of GIS for the full year irradiation values. Based on the irradiation levels, the regions were classified into insolation score regions. The PV potential in these regions was determined by the formula stated above. • Practical Factors Associated with implementation 1. A proper organisational and financial clarity. The stakeholders and party associated with exploitation of the available energy shall be defined. Usually, the project is under the jurisdiction of the federal highway authority since they own major of the roads and a few meters of surrounding areas it. However in most cases the land owned by the federal highway authority is leased to a 3rd party (utility) which then exploits the generated energy. 2. In terms of Operational aspect the maintenance, surroundings (prevention of growth of vegetation so that shading is avoided), Vandalism (graffiti) and theft of PV panels shall be looked into. 3. Design considerations involve proper noise abatement or reflection, performance (self shading effects), safety. ## Motorway Sound barriers: Recent results and new concepts for Technology advancement The paper speaks about the possibilities of integrating photovoltaic units into sound barriers. The author evaluates the bifacial PV modules for North-South oriented roads and monitors the PV yield in relation to positioning of modules and dirt accumulation. • Initially PV sound barrier technology was termed as suitable for only East-West oriented roads. However the use bifacial solar cells can be useful for North-South oriented roads. • In case of bifacial solar cells, about 17% of diffused light and 4% of direct sunlight is lost by reflection at the air-glass interface of the module. However, by using a special saw tooth ridge structure design, the reflection loss can be reduced by 10%. • To estimate the potential of the bifacial prototype, 3 european solar test instrument were used which were mounted in the East, West and South angled 45 deg directions. The results of the monitoring sensors showed that the East-West irradiation levels were comparable to the south oriented sensor. • In order to study the effect of dirt on the PV yield, the modules were mounted at different heights. The results showed that the dirt level was not significant and the irradiation level between highest and lowest mounted panel was small. However, the dirt and emission during winter will be high leading to lower yield. ## Advantages of Thin film solar modules for Sound Barrier System The paper presents the advantages of using the thin film technology namely a-Si and Cd-Te for sound barrier application. • The thin film PV modules have a good temperature coefficient and are ideally suited for vertical mounting applications. Also these modules are favourable for spectral density of solar radiation incident. • The fraction of radiant energy reflected from ground (albedo) and soiling effects are important aspects to be considered while designing a vertical PV noise barrier. The ground albedo is highest for snow covered regions and lowest for soil plain. The vertical mounted PV panels perform better w.r.t soiling and snow accumulation. • The commercially available a-Si and CdTe thin film modules have a back glass cover which acts as a stable, rigid and weather proof cover. This cover also provides noise reflection properties which is useful for integrated PVNB system. • The temperature coefficients of crystalline Silicon PV modules (C-Si) is quite high. At high temperatures the efficiency of the C-Si module drops considerably and has an efficiency similar to that of a-Si modules. • The experimental analysis for the measured spectral solar irradiation level on a typical winter and summer solar noon for a vertical,45 deg tilt and standard STC was done. The winter spectral solar irradiation levels are not favourable for thin film operations while the summer spectral solar irradiation levels were ideal for thin film PV module operating. Also the irradiation level for vertical and 45 deg tilted positions were comparable. • The above factors show a good performance ratio for the a-Si and CdTe thin film modules compared to the C-Si module. This is primarily due to the better temperature coefficients of thin film modules. The thin film vertical module performance is comparable to the optimally tilted C-Si modules  ## Infrastructures Integration of Photovoltaic The paper talks about the basic integration issues when designing an integrated PV technology that serves multiple purpose. In this case the author speaks about the issues related to integration of PV in noise barrier. In case of PVNB, high performance can be achieved by compromising the requirements of low weight, coupling between elements of free of acoustical short circuits and resonance at particular frequencies. However integrated PV panels help to reduce costs since the PV panels by virtue of its design and material can serve dual purpose. The author mentions the different parameters that have to be considered while designing the PVNB system which includes, proper plant construction, safety in normal operating conditions and safety during road accidents, photovoltaic performance, acoustic performance, durability assessment and maintainability of the system. ## Monitoring Results of the Photovoltaic noise barrier at A9 highway in the Netherlands The report provides the monitoring results of the PV system installed along the A9 highway in Netherlands. 1. The PV system consists of 720 AC modules with type A inverters and 1440 AC modules with type B inverters. The monitoring system is based on a decentralised data acquisition system. It consists of the Global data acquisition units, supervision data acquisition units and the analytical data acquistion units. 2. The global monitoring results showed the monthly energy production. Also the in plane irradiation data has been measured from the reference cells from the analytical data unit. The data showed a better performance for modules with type A inverter. 3. The supervision data unit helped to find out any fault or abnormal working condition in the PV module. The energy production data from the Wh reading was used to determine it. The type A inverter showed less than 1% defective operation whereas the inverter B had a maximum of 6% abnormal operating values. 4. The analytical monitoring data was sued to calculate the monthly efficiency data, module efficiency, effect of traffic dust, DC/AC efficiency, grid interference and the irradiation distribution and module temperature. The results of the monitoring system showed that the AC-module with type-A perform well whereas the one with type B have a high failure rate. Accumulated traffic dust caused severe energy losses thus regular cleanning should be carried out. ## Noise Barrier Design Handbook • ACOUSTICAL CONSIDERATIONS 1. Barrier Panel should weigh atleast 20 kg/sq.m for sound loss of 20dB. Barrier Height shall be enough to ensure only a small part of the sound gets diffracted over the edges. Reflection of sound between parallel sound barriers leads to its degradation. For barrier design that overlap each other, the ratio of overlap length to the gap width should be 4:1. • NOISE WALL TYPES 1. Noise Berm: Not Aesthetic, needs adequate drainage requirement, accessibility around noise berm to be considered. 2. Post and Panel Wall: Possibility of sound transmission leaks between stacked panel and panel to post connection. Special considerations for wind loading. 3. Free standing Pre cast concrete: Issues with construction since pre cast requires transportation and traffic implications. 4. Noise Wall: The noise wall structures are usually placed with noise berm and are made up of concrete, wood, plastic, glass, metal and composites. • AESTHETIC CONSIDERATIONS Landscaping, Alignment changes, sloping of panels, drainage should be considered. • DRAINAGE AND UTILITY CONSIDERATIONS Proper water drainage shall be considered. Also care shall be taken for placing road signs, traffic instruments along the noise barriers. Also overhead and underground utility components shall be checked. • Structural Considerations Panel expansion and contraction shall not be constricted. Proper loading data for wind, snow shall be considered. Proper design of barrier footing. • Safety Considerations Fire Safety of the barriers should be considered. Also provisions for emergency access shall be considered. Glare properties of the noise barriers shall be checked. • Cost Considerations 1. Transportation of Material, Equipment, and Work Force costs. 2. Quantity of Barrier :The unit cost of a small quantity of a noise barrier will likely cost more than the unit cost for larger quantities of a barrier. 3. Material Availability: The materials must be specially ordered, or if long manufacturing lead time is required, construction schedules can be affected, adding costs to the barrier construction. 4. Traffic Protection and Detours:The cost of traffic protection/detours may increase barrier installation cost. The contractor may charge a higher unit cost for barrier construction performed close to traffic as compared to construction in a less restricted area. ## Photovoltaics noise barrier: acoustic and energetic study In this paper the best shape of the barrier to optimize the acoustic and energy properties is studied. For the evaluation of acoustic characteristics of the barrier has used the software SoundPLAN. They were studied and compared models of various barrier different from each other for orientation and tilt of the element relative to the horizontal diffracting main barrier. The study was performed with the same boundary conditions, with the same characteristics of the noise source and other conditions including materials, absorption, reflection and morphology of the land etc. The equivalent levels of emission source of the road day and night are are calculated by the software according to the standard NMPB manually setting the percentages of traffic TGM (Average Daily Traffic veh/24h) according to data ANAS and Autostrade for Italy with percentages of heavy vehicles by about 26% during the day and slightly less than 10% in night. In the definition of the way you set the cruise speed of cars and heavy vehicles respectively equal to 130 km/h and 80 km/h (day and night). Then a study of the shape best for the energy yield of PV modules was performed integrated element diffracting the noise barrier. The study was performed by analyzing the energy yield in terms of kWh / year for a plant of 1 kWp of photovoltaic panels installed on the element diffracting thin film of each of the solutions discussed. The analysis has been performed for the 4 test solutions on each of the four orientations of the road set by dividing the quadrant north-south-west-east in 8 equal wedges. Then the guidelines were defined: a) North-south, b) East-west, c) North-east southwest, d) Northwest southeast. the best solution was found to be the one with diffractor tilted 60 degrees from the vertical, ## PV in non building structures-A design Guide Photovoltaics can be instaled in non building structures like car sheds, street lights, information signs and noise barriers. The report summarises the necessary design considerations and also presents some design strategies to facilitate use of PV in non building structures. For PV noise barrier the main problems involve vandalism, theft, soiling, repair and replacement. In order to mitigate the risks of theft and vandalism smart designs shall be used which make the panels protected from thefts and vandalism. Also for retrofit solutions special considerations shall be made to make the mounting components for PV and the non building structure to be separated so that they can be mounted or dismounted independently. ## Highway Renewable Energy: Photovoltaic Noise Barriers ABSTRACT: Highway photovoltaic noise barriers (PVNBs) represent the combination of noise barrier systems and photovoltaic systems in order to mitigate traffic noise while simultaneously producing renewable energy. First deployed in Switzerland in 1989, PVNBs are now found in several countries where transportation agencies have sought ways to find multiple uses of their infrastructure. The PVNB experience documented in literature and supplemented through a series of interviews provides evidence suggesting that noise barriers can be designed to produce renewable energy without compromising their abilities to reduce noise, and do so safely. The business case for a PVNB often hinges on the availability of subsidies or other incentives that promote the renewable energy market. Although the first highway PVNB is yet to be constructed domestically, at least two State Departments of Transportation are currently working with partners to pursue PVNB pilots in the United States. Given the substantial extent of noise barriers in the country, the potential for solar energy production on American noise barriers is likely at least 400 Gigawatt hours annually, roughly equivalent to the annual electricity use of 37,000 homes, and perhaps much higher. ## Noise Barriers in USA- A Summary Report The report was developed to provide information about the problem of highway traffic noise and the United States' response to that problem. • In USA, 78% of the roads and highways are under the jurisdiction of the local government, whereas 19% are under the jurisdiction of the state and rest are under Federal ownership. • The Urban roads in USA comprise of about 1000 miles and account for 64% of the vehicle miles travelled. The rural roads are about 3000 miles and account for 36%. • The Land use and planning control along highways is a complicated issue, due to the many considerations and parties involved in it. Usually the State and local governments are encouraged to practice land use along highway so that land use along noise sensitive highways is avoided. Also in some parts of US, there are laws which makes the developer of residential development along the highways responsible for noise abatement measures. • The EPA has set a maximum noise level of 80db at 50ft from the centreline of travel for heavy and medium sized trucks. • The noise levels are descried using 2 terms Leq and L10. The former corresponds to the equivalent noise level throughout the day whereas the latter corresponds to the noise level exceeded 10% of the time in the noisiest hour of the day. The different noise abatement levels can be defined as, Activity Category Leq L10 Description of Activity Category A 57 (Exterior) 60 (Exterior) Lands on which serenity and quiet are of extraordinary significance and serve an important public need and where the preservation of those qualities is essential if the area is to continue to serve its intended purpose. B 67 (Exterior) 70 (Exterior) Picnic areas, recreation areas, playgrounds, active sports areas, parks, residences, motels, hotels, schools, churches, libraries, and hospitals. C 72 (Exterior) 75 Developed lands, properties, or activities not included in Categories A or B above. D Undeveloped lands. E 52 (Interior) 55 (Interior) Residences, motels, hotels, public meeting rooms, schools, churches, libraries, hospitals, and auditoriums. • The FHWA regulation makes a distinction between projects for which noise abatement is considered as a feature in a new or expanded highway and those for which noise abatement is considered as a retrofit feature on an existing highway. The former are defined as Type I projects, the latter as Type II. • Through the end of 2004, forty-five State DOTs and the Commonwealth of Puerto Rico have constructed over 2,205 linear miles of barriers at a cost of over$2.7 billion (\$3.4 billion in 2004 dollars). Five States and the District of Columbia have not constructed noise barriers to date. The major noise barrier installed in US can be summarized as,
State Linear Miles
California 482.8
Arizonia 155.1
Virginia 127.5
Ohio 112.4
New Jersey 96.9
Thus the report shows a lot of potential in using retrofitting PV solutions for already installed noise barriers. Also the, federal government has planned many noise abatement projects for future highways.