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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.

Discussion

Literature Review

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

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

PV on Noise Barriers

Nordmann, T. and Clavadetscher, L., 2004. PV on noise barriers. Progress in Photovoltaics: research and applications, 12(6), pp.485-495.

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

Gu, M., Liu, Y., Yang, J., Peng, L., Zhao, C., Yang, Z., Yang, J., Fang, W., Fang, J. and Zhao, Z., 2012. Estimation of environmental effect of PVNB installed along a metro line in China. Renewable Energy, 45, pp.237-244.

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

Schirone, L. and Bellucci, P., 2000. On photovoltaics integration in tunnel-shaped sound barriers. In Photovoltaic Specialists Conference, 2000. Conference Record of the Twenty-Eighth IEEE (pp. 1644-1647). IEEE.

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

Remmer, D. and Rocha, J., 2005, August. Photovoltaic noise barrier-Canada. In SESCI 2005 Conference.

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

Nordmann, T., Reiche, K., Kleiss, G., Frölich, A. and Goetzberger, A., 1998, July. Integrated PV noise barriers: six innovative 10 kWp testing facilities, a German/Swiss technological and economical success story!. In 2nd World Conference and Exhibition on Photovoltaic Solar Energy Conversion, Vienna, Austria (pp. 2486-2491).

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,

** Insertion loss is measured 20 m behind the Noise barrier

COMBINING PHOTOVOLTAICS AND SOUND BARRIERS- A FEASIBILITY STUDY

De Schepper, Ellen, et al. "Combining photovoltaics and sound barriers–A feasibility study." Renewable energy 46 (2012): 297-303.

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.

Grottke, M., Voigt, A. and Hartl, F. (2010) ‘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

Schirone, L., P. Bellucci, and U. Grasselli. "Quality issues for photovoltaic-sound barriers." Photovoltaic Energy Conversion, 2003. Proceedings of 3rd World Conference on. Vol. 3. IEEE, 2003.

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

Bellucci, P., et al. "Assessment of the photovoltaic potential on noise barriers along national roads in Italy." Photovoltaic Energy Conversion, 2003. Proceedings of 3rd World Conference on. Vol. 3. IEEE, 2003.

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

PVNB Potential in Europe

Goetzberger, A., T. Nordmann, A. Frölich, G. Kleiss, G. Hille, C. Reise, E. Wiemken et al. "The potential of PV noise barrier technology in Europe." In Proc. 16th European Photovoltaic Solar Energy Conf., Glasgow, p. 2912. 2000.

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

M. Grottke, T. Suker, R. Eyras, J. Goberna, O. Perpinan, A. Voigt, et al. PV soundless – world record “along the highway”– a PV sound barrier with 500 kWp and ceramic based PV modules (2003)

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.