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* Global optimization with genetic algorithm: A heuristic evolutionary technique known as a genetic algorithm (GA), which uses a coding variable instead of the variables themselves, was chosen to determine the optimized parameters that define the limits on efficiency of a specific LSC configuration. | * Global optimization with genetic algorithm: A heuristic evolutionary technique known as a genetic algorithm (GA), which uses a coding variable instead of the variables themselves, was chosen to determine the optimized parameters that define the limits on efficiency of a specific LSC configuration. | ||
* The results show that a single layer configuration is far from optimal and adding a second layer in the LSC with wavelength shifted material in the near infrared region significantly increases the power output, while the gain in power by adding a third layer is relatively small.For perfect luminescent materials the efficiency goes from 21.3% for one layer to 29.5% for two layers and 33.6% for three layers. Hence,under ideal conditions, a third layer does not add very significantly to the overall efficiency. | * The results show that a single layer configuration is far from optimal and adding a second layer in the LSC with wavelength shifted material in the near infrared region significantly increases the power output, while the gain in power by adding a third layer is relatively small.For perfect luminescent materials the efficiency goes from 21.3% for one layer to 29.5% for two layers and 33.6% for three layers. Hence,under ideal conditions, a third layer does not add very significantly to the overall efficiency. | ||
== Better luminescent solar panels in prospect == | |||
[http://www.nature.com/doifinder/10.1038/519298a doi:10.1038/519298a M. Debije, “Renewable energy: Better luminescent solar panels in prospect,” Nature, vol. 519, no. 7543, pp. 298–299, Mar. 2015.] | |||
* LSC panels have not yet come onto the market because of their modest light-to-electricity conversion efficiencies — a result of several light-loss mechanisms in the devices. | |||
* These include restricted absorption ranges, losses from dye-emitted light directed outside the angles required for total internal reflection and absorption of light by the polymer that makes up the light guide. But the crucial loss mechanism that must be addressed is re-absorption of the dye-emitted light. | |||
* Most LSCs use organic fluorescent dyes as the absorbing and emitting species. There are many advantages to organic dyes: they are efficient light absorbers; they can have fluorescence yields approaching 100%; and they are generally soluble in the polymeric light-guide host. However, the Stokes shift of these dyes — that is, the separation of their absorption and emission peak wavelengths — is often small, yielding a significant overlap of the absorption and emission profiles. This causes re-absorption of dye-emitted light when it encounters subsequent dye molecules in the light guide | |||
* The reabsorption results in light loss from the device, either because the reabsorbing dye has a fluorescence yield of less than 100% because the re-emitted light cannot be totally internally reflected and so is lost through the top or bottom surfaces of the light guide. | |||
* Inorganic quantum dots have long been studied as possible alternatives to organic dyes. For example, inorganic particles made up of a Cadmium Selenide (CdSe) core and a cadmium sulfide (CdS) outer shell have been developed for LSCs that have large Stokes shifts and so low re-absorption losses. A promising route to further minimizing losses by using zinc selenide/zinc sulfide (ZnSe/ZnS) core/shell nanocrystals ‘doped’ with ions of manganese (Mn2+) and cadmium (Cd2+) as the luminescent is also being researched species. | |||
* Minimal absorption and emission spectral overlaps would reduce losses of light-guided emission to scattering and absorption by the polymer host itself, dramatically extending the possible operational size of the LSC. | |||
* Once polymer sheets are available that contain such luminophores with good absorption in the peak of the solar pectrum, it will be possible to tackle the second major loss mechanism of LSCs, which is emission through the top and bottom surfaces of the light guide. This can be overcome by applying selective reflectors to the LSC surface5. Successful outcomes on all these fronts could increase the efficiency of LSCs to levels that would enable their use in large-area urban settings. | |||
[[User:Swadhawan]] | [[User:Swadhawan]] | ||
[[User:kkvohra]] | [[User:kkvohra]] | ||
Revision as of 00:10, 10 February 2016
Note to Readers
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
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.
- Top mounted
- Shingles
- Cassette
- Horizontal Zig Zag
- 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.
- 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.
- 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
- 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.
- 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.
- 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.
- 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.
- The BOS for such type of PV module configration shall be capable to take care of the different modules mounted at different tilt angles.
- 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.
- 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
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
- Highly integrated design and easily mountable.
- 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).
- 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.
- 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.
- Another reason was the damage to the panels due to vandalism.
- PVNB GERMANY Shingles Type- 9.1 kWp
- 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.
- 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.
- 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
- 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.
- 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.
- Also, the installation of these modules takes a long time unless they are pre-fabricated in factory.
- The performance index varies between 0.69 (july)- 0.79 (February).
- Also the self shading effect is avoided due to the high inclination angle of the PV panels.
- PVNB Switzerland(A1 Motorway) Type Bifacial- 10kWp
- This is a patented design of TNC Germany. This prototype module design is favourable for roads oriented North-South.
- 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.
- 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.
- 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.
- 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.
- 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.
- PVNB is an alternative technique for space constraint PV structures.
- 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.
- 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.
- 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.
- 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
- Properly sized and oriented
- Minimum of shading effects from poles, stands or adjacent structures.
- Compliant to applicable building and electrical codes.
- Minimum electrical losses over wiring, switches and inverter.
- Properly grounded.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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).
- 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.
- 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
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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
US Federal Highway Administration department Noise barrier Design guidelines
- ACOUSTICAL CONSIDERATIONS
- 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
- Noise Berm: Not Aesthetic, needs adequate drainage requirement, accessibility around noise berm to be considered.
- Post and Panel Wall: Possibility of sound transmission leaks between stacked panel and panel to post connection. Special considerations for wind loading.
- Free standing Pre cast concrete: Issues with construction since pre cast requires transportation and traffic implications.
- 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
- Transportation of Material, Equipment, and Work Force costs.
- 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.
- 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.
- 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
IEA Report on design guides for PV in non building structures
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.
Solar Potential Using GIS
Using GIS to estimate the replacement potential of solar energy for urban dwellings
This paper focuses on a system design using GIS for urban planners.advisers. The system design combines commercial database and GIS packages to provide a flexible means of predicting the solar energy potential and energy consumption of dwellings. By incorporating customized tools designed to derive useful data directly from digital maps and aerial photographs, it addresses the significant problem of data collection for urban-scale energy modelling The Solar Energy Planning (SEP) system software is used , which combines widely used commercial database and GIS (geographical information system) packages. These are dynamically linked to provide a flexible and efficient way of deriving and exploiting useful data from digital maps and aerial photographs by means of a novel set of customized GIS tools. A city area of interest to the user could be selected by using the area select custom tool in the GIS. The map data derivation tools could then extract the data from footprints linked to Address Point data found within the search area.
Multicriteria GIS modeling of wind and solar farms in Colorado
The objectives of this research are to: 1) determine which landcover classes are affiliated with high wind and solar potential; and 2) identify areas that are suitable for wind and solar farms using multicriteria GIS modelling techniques.
The following variables were obtained from digital databases:Solar Potential,Distance to Transmission Lines,Distance to Cities,Population Density,Distance to Roads,Land cover,Federal Lands. Ideal conditions were defined for these and also, each was assigned weights based on their relative importance to one another. Annual direct normal solar radiation GIS data for concentrating systems, which track the sun throughout the day and transmission lines vector files were also obtained from NREL. The GIS model indicated that ideal areas for solar development are located in northwestern Colorado and east of Denver. Only 191 km2 of the state had model scores that were in the 90e100% range. These results suggest that the variables used in this analysis have more of an effect at eliminating non-suitable areas for large-scale solar farms
Solar electricity prospects in Oman using GIS-based solar radiation maps
Without an accurate database and knowledge of most appropriate locations of renewable energy applications in the country, investment in renewable energy will not be efficient and profitable. This can be achieved by producing solar radiation maps.Precise solar maps will be increasingly important as investors seek assurance that deals will be really profitable. Better information means quicker decisions saving money and bringing renewable energy resources into production more quickly. This paper discusses solar power prospects in Oman.The methodology of producing solar radiation maps using GIS tools is then discussed. A solar radiation map can be generated by using solar radiation data obtained from measurement stations. However, such a method is not applicable to many parts of the globe due to insufficiency of measurement stations.
Topography is a key factor that determines the spatial variability of radiation. Variation in elevation, orientation (slope and aspect), and shadows cast by topographic features all affect the amount of radiation received at different locations. This spatial variability also changes with time of day and time of year. The solar radiation analysis tools, in the ArcGIS Spatial Analyst extension, enables to map and analyze the effects of the sun over a geographic area for specific time periods. It accounts for atmospheric effects, site latitude and elevation, steepness (slope) and compass direction (aspect), daily and seasonal shifts of the sun angle, and effects of shadows cast by surrounding topography
It is found that if only 10% of the land of Oman with a slope less than 1% is considered an exploitable land for the parabolic trough CSP technology, then the total calculated potential of yearly electricity generation would be about 7.6 million GWh, which is many multiples of (680 times) the current generation supply in Oman.
PV site suitability analysis using GIS-based spatial fuzzy multi-criteria evaluation
This paper presents some preliminary results from a research study conducted on solar energy resource assessment in Oman. Different PV technologies were considered for implementation.
Comparing the CSP and PV technologies, the CSP necessitates larger amounts of water for cooling and mirror washing than the PV. Therefore, for arid countries with scarce fresh water resources, the PV technology is more suitable, environment friendly, and economical. Besides, the implementation of PV plants is much faster than the CSP ones, which gives it more flexibility to cope easily with the development of the grid system.
Using GIS and Multi- Criteria Analysis (MCA) together provide a fine lens for the optimal site selection for plants. The principal of the MCA is to condense complex problems with multiple criteria into finest ranking of the best scenarios from which an option is selected. The analytical hierarch process (AHP) is another approach used in decision-making strategies. It is a robust structured approach dealing with complex decisions. The AHP is based on the additive weighting model
Solar energy resource assessment and site suitability for large PV farms implementations is affected by different factors which can be classified in three main categories: Technical, Economical and Environmental. Some factors such as-dust and sand risk factors are only specific to the region and may not apply for other countries with temperate climate. The tool used in this analysis is the Fuzzy Logic Ordered Weight Averaging (FLOWA) module developed by Boroushaki and Malczewski Electric power generation potential of the country or a region is estimated based on the calculated yearly solar radiation per unit surface, the total exploitable area, and the efficiency of the technology used to convert solar radiation into electricity.
Mapping of solar energy potential in Indonesia using artificial neural network and geographical information system
The objective of this study is to determine the theoretical potential of solar irradiation in Indonesia by using artificial neural networks (ANNs) method.As developing country and wide islands area, Indonesia has the limitation on the number of meteorological station to record the solar irradiation availability; this study shows the ANN method can be an alternative option to estimate solar irradiation data. Since ANN is highly nonlinear and requires no prior assumption concerning the data relationship, it has become a useful tool for predicting solar irradiation. Particularly, in the meteorological and solar energy resources fields, ANN based models have been successfully developed to model different solar radiation variable in many locations.Inputs for the networks are latitude, altitude, and mean sunshine duration. In order to train the neural network, satellite data from 30 cities spread over Indonesia were used as training (25 cities) and testing (5 cities) data. ArcGIS was used as effective tool to visualize the map of solar resources by provincial boundaries in monthly basis.
Geographical Information Systems(GIS)and Multi-Criteria Decision Making(MCDM) methods for the evaluation of solar farms locations: Case study in south-easternSpain
This paper is based on the combination of a Geographic Information System (GIS)and tools or multi-criteria decision making(MCDM)methods in order to obtain the evaluation of the optimal placement of photovoltaic solar power plants in the area of Cartagena in southeast Spain. The combination GIS–MCDM generates an excellent analysis tool that allows for the creation of an extensive cartographic and alphanumeric database that will later be used by multi-criteria methodologies to simplify problems to solve and promote the use of multiple criteria. n GIS two types of criteria will be reflected: constraints or restrictive criteria, and weighting criteria or factors. Constraints or restrictive criteria make it possible to reduce the area of study by discarding those areas that prevent the implementation of renewable energy plants. These criteria is obtained from the legislation. Through the use of MCDM the criteria or factors mentioned are weighted in order to evaluate potential sites to locate a solar plant. Analysis and calculation of the weights of these factors is conducted using Analytic Hierarchy Process (AHP). The assessment of the alternatives according to their degree of adequacy is carried out through the TOPSIS method TOPSIS is based on the concept that the chosen alternative should have the shortest distance from the Positive Ideal Solution (PIS) and the farthest from the Negative Ideal Solution (NIS). The final ranking is obtained by means of the closeness index. This paper has demonstrated how it is possible to combine a Geographic Information System with Multi-criteria Decision Making Methods (GIS–MCDM) for use or application in the field of renewable energies, for example when a developer wants to implant a photovoltaic solar farm with specific characteristics (surface to occupy, installed power, etc.), the starting point is to select the best location based on such characteristics. Using GIS–MCDM tools, the difficult task of searching for sites is facilitated so the developer can choose those areas which, from an energy point of view, are optimal and they are also adapted to his or her needs.
However, the analysis conducted has weaknesses that could be strengthened by including linguistic labels in the methodology which could be applied in the definition of certain factors whose nature is qualitative.
GIS-based approach for potential analysis of solar PV generation at the regional scale: A case study of Fujian Province
This paper presents a case study of using high resolution grid map of solar radiation combined with the other restriction factors to evaluate the comprehensive potential analysis of solar PV generation at the regional scale, in order to present a framework of decision support tool for solar energy management in a regional area. The cost of PV generation is calculated based on the geographical distribution of technical potential. Moreover, geospatial supply curve (GSC) is employed to portray the evolution of available potential of photovoltaics (PV) generation with the increase of the generation cost. By integrating the economic evaluation variables of net present value and simple payback period, grid-based economic feasibility of PV generation project is then carried out
the first step is to evaluate the potential for exploiting solar energy sources, including geographical and technical potential in suitable areas with the aid of GIS spatial analysis functions. The second step is to assess economic feasibility for PV generation. To exactly estimate the solar radiation for the study area, a high resolution solar radiation map for Fujian Province was calculated by using the solar radiation analyst module of ArcGIS 9.3. The module accounts for atmospheric effects, site latitude and elevation, steepness (slope) and compass direction (aspect), daily and seasonal shifts of the sun angle, and effects of shadows cast by surrounding topography. For assessing the amount of electricity potential from solar PV,three categories of potential are defined :Geographical potential, Technical potential & Economic potential. The cost-benefit analysis is critical for appraising the feasibility of PV projects Basically This paper presented a computational procedure to derive a regional model of solar PV generation potential and its economic feasibility with the aid of the solar radiation analysis tool and map algebra functionality in the ArcGIS software.
GIS-based solar farms site selection using analytic hierarchy process (AHP) in Karapinar region, Konya/Turkey
Site selection for solar farms is a critical issue for large investments because of quality of terrain, local weathering factors, proximity to high transmission capacity lines, agricultural facilities and environmental conservation issues. Multi criteria evaluation methods are often used for different site selection studies. The purpose of this study was to determine suitable site selection for solar farms by using GIS and AHP in the study area. The final index model was grouped into four categories as “low suitable”, “moderate”, “suitable” and “best suitable” with an equal interval classification method.
n the first step, GIS data sets of study area (residential areas, land use, roads, slope and transmission lines) were collected for study area from different sources.In the next step, the weights for each of identified environmental and economic objectives were calculated with AHP which is one of the MCDM methods using Microsoft Excel and performed overlay analysis using a GIS for site selection of solar farms. In this study, land suitability map was prepared as five map layers including distance from residential, land use, distance from roads and distance from transmission lines. ArcGIS software was used in this process for overlay analyses. Determined numerical values from LSI divided into four grades (low suitable, moderate, suitable and best suitable) according to criteria and buffer zones were built. The higher score is more suitable area for solar farm areas.
Final suitability map was created for combined all criteria.
GIS-based photovoltaic solar farms site selection using ELECTRE-TRI: Evaluating the case for Torre Pacheco, Murcia, Southeast of Spain
This paper proposes the use of a Geographic Information System (GIS) in order to identify the best plots suitable for installing photovoltaic solar farms in the Municipality of Torre Pacheco, in the southeast of Spain. The plots are classified according to multiple evaluation aspects, by developing a multi criteria model and applying the ELECTRE-TRI method using the Decision Support System IRIS.The GIS provides a cartographic and alphanumeric database, including two factors of distinct nature: restrictions and criteria. The restrictions are entered into the GIS using layers defined from the current legislation which reduce the study area by eliminating those areas in which photovoltaic solar farms cannot be implemented. ELECTRE methods are based on the construction and exploitation of an outranking relation. Once all the parameters have been introduced, the IRIS program is run providing a graph. The main contribution of this paper is the combination of this geographic information system with a multicriteria decision analysis Method (ELECTRE-TRI, which is based on the exploitation of an outranking relation devoted to the sorting problem)
Solar power potential mapping in India using remote sensing inputs and environmental parameters
The paper maps the district-wise potential for concentrating solar power (CSP) and centralized solar photovoltaic (SPV) technology based power plants in India. The evaluation is based on remotely-sensed annual average global horizontal irradiance (GHI) and direct normal irradiance (DNI) provided by National Aeronautics and Space Administration (NASA) surface meteorology and solar energy program. The solar irradiation data (GHI and DNI), land-use data and Digital Elevation Model (DEM) were used in GIS environment while employing land-use criteria and topography to exclude unsuitable sites for harnessing solar energy. Furthermore, land-cover factor, number of sunshine hours and conversion efficiencies were taken into account to calculate technical potential in suitable land areas for solar power development. Remote sensing and GIS could be utilized to assess the potential for various renewable energy alternatives while including aspects such as, geographical location , technology used for harnessing renewable energy,economic viability and others. The main objective of this study is to calculate district-wise technical potential for solar energy in India using remotely sensed solar irradiation data while considering land-use and topography exclusion criteria. The technical potential is calculated both for CSP and centralized SPV technology independently to identify geographical locations best suited for respective technology and the hybrid ones. For SPV potential calculation, all the areas with a solar resource equal to or greater than 4.0 kWh/m2/day were included. The solar potential results presented in this study for Indian districts would certainly benefit planners and policy makers to make sound decisions for site selection, planning of solar parks, and installation of suitable solar power technologies at the best suitable sites.
GIS-based method to evaluate the photovoltaic potential in the urban environments: The particular case of Miraflores de la Sierra
The purposes of this study were to develop a multi-criteria approach based on Geographic Information Systems (GIS), Light Detection and Ranging (LIDAR) and hourly horizontal radiation data to explore the possibility of installing photovoltaic (PV) systems in urban environments, and to evaluate the resulting annual production of electricity. LIDAR data provide an accurate description of urban environments by creating a Digital Surface Model (DSM), which is used to calculate the local inclination and orientation of roofs by means of the shadow effect of the various components (including other buildings and trees). The radiation incident on the panels is calculated with a geometric method based on the hourly horizontal radiation broken down into its diffuse and direct components. the efficiency of the panels and different sources of losses, especially temperature, are incorporated into the assessment of the effective production. The five most common panel technologies are considered: Si Mono, Si Multi, CIS, TeCd, Ai amorfo
This article presents an efficient model developed in ARCGIS using LIDAR data.Depending on the primary purpose, the choice of the most suitable technology may be different. For example, in the case study, Si amorphous panels are the most efficient, but their total production is less than a third of what could be obtained with Si mono crystalline panels. Therefore, the minimum energy produced is an important constraint on the choice of technology.
Solar resources and power potential mapping in Vietnam using satellite-derived and GIS-based information
The present paper presents maps of the solar resources in Vietnam and of the solar potential for concentrating solar power (CSP) and for grid-connected photovoltaic (PV) technology. The mapping of solar radiation components has been calculated from satellite-derived data combined with solar radiation derived from sunshine duration and other additional sources of information based on reanalysis for several atmospheric and meteorological parameters involved. Geographic Information Systems (GIS) have been used for combining the solar potential with the land availability according each scenario to deliver the technical solar potential maps of Vietnam. Vietnam has a dense and long database of sunshine duration measurements consisting of 171 stations distributed along the country which have been recording daily values of sunshine duration since 1984. Meteosat IODC (Indian Ocean Data Coverage) images for the period 2003–2012 were used to compute daily values of GHI and DNI (Direct Normal Irradiation) in Vietnam. Solar global irradiation and additional meteorological variables have been computed with SKIRON model. SKIRON is a mesoscale numerical model based on the Eta prediction model, and uses input data from the Global Forecast System (GFS)On the other hand, the knowledge of solar radiation components for clear sky conditions, mainly GHI and direct normal irradiance (DNI), is frequently useful since it determines the upper bound of the solar resource expected for a specific site. The solar potential for Vietnam has been estimated and mapped from several hypothesis and scenarios concerning the solar resource availability and the solar technology systems to be taken into account. Solar resource availability has been obtained from the solar resource mapping for Vietnam estimated from satellite imagery, ground measurements and reanalysis of several atmospheric and meteorological variables.
Using GIS analytics and social preference data to evaluate utility-scale solar power site suitability
Determining socially acceptable and economically viable locations for utility-scale solar projects is a costly process that depends on many technical, economic, environmental and social factors. This paper presents a GIS-based multi-criteria solar project siting study conducted in the southwestern United States with a unique social preference component. Proximity raster layers were derived from features including roads, power lines, and rivers then overlain with 10 × 10 m raster terrain datasets including slope and potential irradiance to produce a high resolution map showing solar energy potential from “poor” to “excellent” for high potential counties across the southwestern United States. Similar maps were produced by adding social acceptance data collected from a series of surveys showing the potential public resistance to development that can be expected in areas of high solar energy suitability. Applying social preferences to the model significantly reduced the amount of suitable area in each of the selected study areas. The methods demonstrated are expected to help reduce time, money, and resources currently allocated toward finding and assessing areas of high solar power suitability. In addition to physical constraints, social attitudes can also affect where and solar development occurs. While research demonstrates that majority of Americans support renewable energy generally and solar energy in particular and development of utility-scale solar has been impeded due obstacles such as cost, efficiency, and regulations. A typical explanation of slow development tended to place blame on local residents' opposition to proposed development.
Indeed, even environmentalists have opposed proposed projects due to the impacts of solar facilities on rare desert plants and animals In the San Luis Valley of Colorado, local residents sided with environmental groups to oppose a concentrated solar power (CSP) facility due to the impact the project would have on the local ecosystem, especially with regards to transmission line siting. This example is not an isolated case.
Each selected site was processed by PVMapper [38] to analyze the maximum slope, minimum irradiance value, and distance to nearest river, road, and major grid power line. The PVMapper scorecard tool uses GIS layers to give an overview of the site terrain slope, soil, solar irradiance potential and land cover as well the distance to such features as the nearest transmission lines, rivers, and roads. Avoiding unforeseen public resistance will overall reduce the soft costs associated with solar development.
Modelling solar potential in the urban environment: State-of-the-art review
doi:10.1016/j.rser.2014.08.060 S. Freitas, C. Catita, P. Redweik, and M. C. Brito, “Modelling solar potential in the urban environment: State-of-the-art review,” Renewable and Sustainable Energy Reviews, vol. 41, pp. 915–931, Jan. 2015. Cityscapes provide a complex environment, where solar radiation is unevenly distributed, especially since urban features started to propagate more and more vertically. Due to the dynamic overshadowing effects present on building surfaces, quantifying these phenomena is essential for predicting reductions in solar radiation availability that can significantly affect potential for solar energy use. Numerical radiation algorithms coupled with GIS tools are a pathway to evaluate those complex effects. Accurate representation of the terrain, vegetation canopy and building structures allows better estimation of shadow patterns. Higher spatial and temporal resolutions deliver more detailed results, but models must compromise between accuracy and computation time. In this paper, models ranging from simple 2D visualization and solar constant methods, to more sophisticated 3D representation and analysis, are reviewed. Web-based solar maps, which rely on the previous features to successfully communicate the benefits of the solar resource to the public and support in the policy-making process, are also addressed. Meteorological stations generally measure global and diffuse irradiation received on the horizontal plane and the direct component can be obtained from: Ghoriz=Dirhoriz+Difhoriz=DirnormcosZ+Difhoriz where Ghoriz is the global horizontal irradiance, Dirnorm is the direct normal irradiance, Difhoriz is the diffuse horizontal irradiance and Z is the sun׳s zenith angle. The paper showed that the improving ability to describe the physical behaviour of solar radiation has been incorporated into the methods, with model after model trying to overcome previous limitations. Thanks to the fast development of information technology, solar mapping models are today far more powerful, allowing user-friendly detailed analysis and representation of the radiation phenomena, thus reaching out outside the traditional architecture and engineering niches. An emerging trend is the employment of these GIS tools for energy analysis in the urban environment.
U.S. Renewable Energy Technical Potentials: A GIS-Based Analysis
- Utility-Scale Photovoltaics (Urban)
The process for generating technical estimates for urban utility-scale PV begins with excluding areas not suitable for this technology. First the areas are limited to those within urbanized area boundaries as defined by the U.S. Census Bureau (ESRI 2004) and further to those with slopes less than or equal to 3%. Parking lots, roads, and urbanized areas are excluded.The remaining land is grouped into contiguous areas and areas less than 18,000 square meters (m2) are removed to ensure that total system size is large enough to be considered a utility-scale project. The PV system assumed in this analysis was a 1-axis tracking collector with the axis of rotation aligned north-south at 0 degrees tilt from the horizontal, which has a power density of 48 MW per square kilometer (MW/km2)
- Utility-Scale Photovoltaics (Rural)
Technical potential estimates for rural utility- scale PV begin by first excluding urban areas as defined by the U.S. Census Bureau’s urbanized area boundaries data set. percent slope for areas outside the urban boundaries is calculated and all areas with slopes greater than or equal to 3% are eliminated. Federally protected lands, inventoried roadless areas, and areas of critical environmental concern are also excluded, as they are considered unlikely areas for development.
- Concentrating Solar Power
Concentrating solar power (CSP) is defined as power from a utility-scale solar power facility in which the solar heat energy is collected in a central location. The technical potential estimates for CSP were calculated using satellite-modeled data from the National Solar Radiation Database (Wilcox, 2007), which represent annual average direct normal irradiance (DNI). Only areas with DNI greater than or equal to 5 kWh/m2/day are considered viable.
Luminescent Solar Concentrator
Luminescent solar concentrators operate on the principle of collecting radiation over a large area, converting it by luminescence and directing the generated radiation into a relatively small output target. They can be produced in many different colors, can be cut to essentially any desired shape, and are relatively robust. Alongside the A2 highway near Den Bosch, The Netherlands, two test noise barriers are installed that generate solar energy. Playing a key role in the test are the LSC panels. Owing to their many colors the LSC are visually very attractive, which makes them ideal for use in many different situations in the built environment
Read more at: http://phys.org/news/2015-06-solar-energy-noise-barriers-highway.html#jCp
Direct versus indirect illumination of a prototype luminescent solar concentrator
The luminescent solar concentrator could find application as an alternative way of generating electricity from sunlight in urban settings by virtue of its aesthetic and performance qualities. An LSC is a plastic plate filled or topped by luminescent molecules. The luminophores absorb incident sunlight and re-emit this light at longer wavelengths. A significant fraction of the re-emitted light remains trapped within the plastic light guide by total internal reflection. The main exit for this trapped light is from the edges of the device, where one can mount thin, long photo voltaic (PV) cells for converting the emission light into electricity. A positive feature is the capability of absorbing sunlight from both front and rear sides and the potential to function in diffuse light conditions.
- In particular, it has long been stated that the device functions equally well in direct and diffuse light, especially useful in the built environment but with little verification of this statement. In this work,the validity of this claim has been tested by comparing the performance of the luminescent solar concentrator in outdoor conditions ranging from clear to cloudy.
- A prototype LSC was assembled by Airbus Defence and Space Netherlands from a 60 * 40 * 2 cm3 cast Plexiglas plate (Evonik) doped with Lumogen F 305 dye. The plate is held vertically be means of a handling frame made of aluminum. A pyranometer was used to collect solar irradiation data at the test site which was then fed to a data logger. The power efficiency is thus calculated based on the ratio between the power generated (by the cells) from the entire edge surfaces of the light guide to the solar irradiation incident on the primary surface of the light guide.
Direct vs. indirect incident illumination: The most striking trend in the results is the dramatic jump in normalized edge efficiency measured simultaneous with the drop in solar irradiance. Normalized electrical output efficiency increases by up to 100% in these conditions.
- Explanation for increased efficiency: It has been shown by ray-tracing modelling techniques that the photon collection efficiency of a Red 305 based LSC is 21% with diffuse light while only 9% with the direct component. This is because short wavelength light is scattered more effectively in the atmosphere so the diffuse spectrum is blue rich and can be better harvested by the LSC. Under sunny conditions, the fraction of light coming in from behind the LSC is small compared to the front side illumination. However, under cloudy conditions and late evenings when the solar disk disappears, the difference between front and back becomes smaller. As a result, this unrecorded rear-side irradiance under cloudy conditions could contribute a larger fraction to the electrical output, affecting the efficiency values.
- In an urban setting there is a great variety of lighting conditions, both in intensity and spectral distribution. Solar energy generators must contend with clouds, shading, a moving solar disk, and seasonal changes. One of the advantages of employing luminescent solar concentrator devices in the built environment is their relative insensitivity to changes in these lighting conditions.
- The constant energy output demonstrates less tendency to ‘spike’ under different lighting conditions, and thus makes the device easier to integrate in a global energy network, providing a reliable source of power. The absolute output of the LSC is considerably less than a PV panel of the same size. However, the aesthetic difficulty in integrating the PV panel coupled with its sometimes problematic behavior in low light, cloudy, or warm conditions could leave room for the LSC to be used in areas where PV panels are not considered viable.
Optimizing luminescent solar concentrator design
- In this paper an optimization analysis is presented based on the implementation of a genetic algorithm, the theoretical
limits of efficiency are provided for one, two and three layer configurations and give guidance for the properties required for luminescent materials, such as quantum nano crystals, to operate efficiently in planar LSC configurations.
- All luminescent matter must obey a thermodynamic relationship between emission and absorption called the Kennard-Stepanov (K-S) relationship.It establishes a relationship between absorption, emission and temperature. The K-S relation requires that there will be some emission at any energy where there is absorption (and vice versa).
- The objective of the global optimization was to find the optimal emissive energy and the respective energy absorption edge that provide the maximum optical efficiency for a given LSC configuration while maintaining the K-S condition.
- Model of perfect luminescent matter: Because the K-S theory relates emission and absorption, there must be absorption in the perfect emission band and emission in the perfect absorption band.
- The perfect K-S model has four parameters: the band gap energy, the width of the perfect emission peak, the absorption threshold, and the crossover energy.
- Global optimization with genetic algorithm: A heuristic evolutionary technique known as a genetic algorithm (GA), which uses a coding variable instead of the variables themselves, was chosen to determine the optimized parameters that define the limits on efficiency of a specific LSC configuration.
- The results show that a single layer configuration is far from optimal and adding a second layer in the LSC with wavelength shifted material in the near infrared region significantly increases the power output, while the gain in power by adding a third layer is relatively small.For perfect luminescent materials the efficiency goes from 21.3% for one layer to 29.5% for two layers and 33.6% for three layers. Hence,under ideal conditions, a third layer does not add very significantly to the overall efficiency.
Better luminescent solar panels in prospect
- LSC panels have not yet come onto the market because of their modest light-to-electricity conversion efficiencies — a result of several light-loss mechanisms in the devices.
- These include restricted absorption ranges, losses from dye-emitted light directed outside the angles required for total internal reflection and absorption of light by the polymer that makes up the light guide. But the crucial loss mechanism that must be addressed is re-absorption of the dye-emitted light.
- Most LSCs use organic fluorescent dyes as the absorbing and emitting species. There are many advantages to organic dyes: they are efficient light absorbers; they can have fluorescence yields approaching 100%; and they are generally soluble in the polymeric light-guide host. However, the Stokes shift of these dyes — that is, the separation of their absorption and emission peak wavelengths — is often small, yielding a significant overlap of the absorption and emission profiles. This causes re-absorption of dye-emitted light when it encounters subsequent dye molecules in the light guide
- The reabsorption results in light loss from the device, either because the reabsorbing dye has a fluorescence yield of less than 100% because the re-emitted light cannot be totally internally reflected and so is lost through the top or bottom surfaces of the light guide.
- Inorganic quantum dots have long been studied as possible alternatives to organic dyes. For example, inorganic particles made up of a Cadmium Selenide (CdSe) core and a cadmium sulfide (CdS) outer shell have been developed for LSCs that have large Stokes shifts and so low re-absorption losses. A promising route to further minimizing losses by using zinc selenide/zinc sulfide (ZnSe/ZnS) core/shell nanocrystals ‘doped’ with ions of manganese (Mn2+) and cadmium (Cd2+) as the luminescent is also being researched species.
- Minimal absorption and emission spectral overlaps would reduce losses of light-guided emission to scattering and absorption by the polymer host itself, dramatically extending the possible operational size of the LSC.
- Once polymer sheets are available that contain such luminophores with good absorption in the peak of the solar pectrum, it will be possible to tackle the second major loss mechanism of LSCs, which is emission through the top and bottom surfaces of the light guide. This can be overcome by applying selective reflectors to the LSC surface5. Successful outcomes on all these fronts could increase the efficiency of LSCs to levels that would enable their use in large-area urban settings.