Solar Energy

Solar Energy

  • Tony Maine added an answer:
    2
    What can be the possible ways of increasing efficiency of solar cells using graphene?

    Graphene having excellent properties can be utiized for solar cells and thus efficiency of a solar cell can be increased.

    Tony Maine

    Sadly I don't know of any solar cell technology either in use or under development that is going to substantially undercut the cost of silicon, for two reasons. The investment required will be at least as much as has been put into silicon - maybe a billion US$ over 40 years, and secondly because the photoactive layer is now such a small part of a solar panel making it cheaper will not have a strong effect on the cost of the panel. I am not saying that we shouldn't do it, but be aware of what you're up against in silicon! It will not be easy to replace it on a large scale. Maybe perovskite cells integrated into the roof structure (Building integrated PV) will do the job. We just don't know.

  • Pavan Kumar A. V. added an answer:
    5
    The effect of load on maximum power point in PV systems?

    Does the change in load affects maximum power point in PV systems? (I think the answer is Yes). Then, why do all MPPT techniques only concern themselves with the changes in environmental conditions (irradiation)?

    Pavan Kumar A. V.

    MPPT technique is employed to track the MPP of the PV cell depending on the I, V samples collected from the PV. The output voltage of PV cell is directly depend upon the Solar Illumination. If the solar illumination varies the output voltage of PV will vary. In order to have a constant DC output voltage a boost converter or buck-boost converter is employed as per the desired output voltage level. In this scenario change in DC load will not effect the MPP of the PV. So, MPPT will be tracking the MPP of the PV panel their by adjusting the duty cycle of the converter to meet the required load at constant output voltage.    

  • Fidelis Abam added an answer:
    6
    Can solar energy be used to power heavy duty trucks, is there any working system at the moment?

    The transportation sector is one of the major contributor of CO2 into the atmosphere. This situation is serious especially in developing economy with low air quality standards, where goods are transported with heavy diesel trucks. Is there any hope in powering diesel trucks with solar energy

    Fidelis Abam

     Thanks Tony for your scientific illustrations I do hope for scientific break through.

  • Federico Brivio added an answer:
    2
    Can anyone please inform me the roles of different layers used in Perovskite Solar Cell? I want to know the details mechanism. ???

    Please share the details mechanism of the different layers used in Perovskite Solar cell e.g, FTO, TiO2, Perovskite layer, hole transporting layer, Ag/Au.

    Thank you.

    Federico Brivio

    Simple description of Perovskite Solar cell e.g,
    FTO  = conductive transparent substrate
    TiO2 = Semiconductor where the perovskite is deposited. This create a mesoporous interface, where electron are injected.
    Al2O3 = Substituted TiO2  in some cell, in this case, the electron can not be injected, and it acts as a simple support for the perovskite.
    Perovskite layer = adsorb the light and create the e-h couple. The electron can be injected in the inorganic support (TiO2 or Al2O3) or transported. Same for holes, that are usually injected in an inorganic transport layer (as CuI) or in an organic one
    hole transporting layer = it covers the perovskite and collects the hole. Can be organic usually or inorganic.
    Ag/Au = back contact

  • Abdelhalim Zekry added an answer:
    3
    How to calculate bandgap alignment for different layers used in Perovskite solar cell??

    I do want to know the procedure of the bandgap calculation and the drawing software. Is this draw manually?

    + 1 more attachment

    Abdelhalim Zekry

    The energy band alignment is dictated by the function of the layers in the solar cell. It is so that the absober material say the perovskite must have an energy gap corresponding to the maximum conversion efficiency of about 1.35 eV. Then one has to add on one side an electron transport layer ETL whose conduction band edge Ec slightlylower than the conduction band edge of the absorber while at the same time its valence band edge is lower than that of the absorber to reflect the holes and prevent them flowing in the ETL. At the other side of the absorber there exist a hole transport layer HTL with the valence band edge is slightly above that of the absrber to facilitate the flow of the holes in its direction while its conduction band edge lies above that of the aborber to reject the electrons and prevent them from flowing in the HTL.The metal electrode adjacent the ETL must have fermilevel below that of the ETL. The metal electrode contacting the HTL must have fermilevel above that of the HTL.

    After selecting the appropriate materials , there are two methods to align the bands. They can be drawn with respect to a reference level called the vacuum level. This is the alignment before contacting the materials. After contacting the materials they are aligned by the Fermi level. Under thermal equilibrium the fermilevel will be a horizontal line through out the structure. The fermi levels is that level with equal probability of electrons and holes. Intrinsic semiconductors have their Fermi level in the middle of the energy gap. The fermi level shifts towards the bands if the materiel is doped. The fermi level of the metal lies under the vacuum level with the work function of the material. The conduction band edge of a semiconductor material lies under the vacuum level by the electron affinity.

    Knowing these information one can easily draw the energy band diagram of the whole structure. It is a simple diagram and can be drawn easily by any drawing program or manually.

  • Samar A. El-Mekkawi added an answer:
    5
    How can I convert light intensity in lux to micro moles per square meter per second of PAR?

    PAR is photosynthetic active radiation in 400-700nm.

    Samar A. El-Mekkawi

    John_Flores-Mclaughlin; I interest your answer however would you provide us the reference of your attachment 

  • Lucien Wald added an answer:
    19
    How can I find clear sky days in a year using meteorological measurements, primarily using GHI (Global Horizontal Irradiance) measurements?

    Please suggest clear sky models/techniques/formulas which can be employed using a dataset containing the following given meteorological measurements to identify clear sky days in a year. 

    1. Daily Global Solar Radiation (GHI)         : Avg,Max,Min
    2. Daily Extraterrestrial Solar Radiation     : Avg
    3. Daily Air Temperature                            : Avg, Max, Min
    4. Daily Relative Humidity                          : Avg, Max, Min
    5. Daily Sunshine Duration                        : Avg, Max
    6. Daily Wind Speed                                  : Avg, Max, Min

    I intend to implement the suggested equations/formulas/models in matlab.

    Regards,
    Ibrahim

    Lucien Wald

    Your problem does not have accurate solution even if you have set up a precise definition of what is a clear-sky because your data is not sufficiently resolved in time. I backup the answer of Chris Gueymard and Frank Vignola on the use of a model predicting the irradiation under cloudfree sky, a so-called clear-sky model

    As written by my colleagues, such models need inputs that you may not have though they are likely available. Given your objective, you may find an interest to use the McClear service available at http://www.soda-pro.com/web-services/radiation/mcclear.

    It is a service covering the world that delivers time series of irradiation that would be observed in a specific site under clear sky conditions, with a time step ranging from 1 min to 1 month. The Global, Direct and Diffuse Horizontal Irradiation, as well as the Beam Normal Irradiation are provided. The data are available from Jan. 2004 up to current day-2. Inputs about atmosphere properties are taken automatically from the MACC (now CAMS) database. MACC: Monitoring Atmosphere Composition and Climate, a series of European-funded projects. CAMS: Copernicus Atmosphere Monitoring Service, an operational program to deliver info and data on several properties of the atmosphere (mostly aerosols and gases) and other data, among which solar irradiation at surface.

    Access to data is free and unlimited provided you have registered. You may also be interested in knowing that this service obeys the Web Processing Standard of the OGC and that you may call it automatically (after registration). Help may be found at http://www.soda-pro.com/help/macc-rad/automatic-access.

    Details on the model may be found at http://www.atmos-meas-tech.net/6/2403/2013/amt-6-2403-2013.html

  • Qazi Zafar Iqbal added an answer:
    5
    How can i integrate solar energy and Diesel Generator ?

    How can i integrate solar energy and Diesel Generator to make it one source of energy i.e micro grid and then use for my must run or regular load,comments and code segment will be appreciated.

    Qazi Zafar Iqbal

    thanks Sir Tony and Fidelis

  • Anurag Pandey added an answer:
    9
    Any advice on implementation of Maximum power point tracking systems (MPPT) in solar PV’s?

    How the MPPT system is implemented? Is MPPT of solar PV arrays possible without using microcontrollers?

    Anurag Pandey

    Maximum Power point tracking system can be implemented using four methods mainly (using Micro controllers, IC, Artificial intelligence/neural network and PLC).

  • Jan-Martin Wagner added an answer:
    5
    If a regular Diode is exposed to sunlight, generates voltage? Why the circuit model of PV cell is a current source in parallel with a reverse diode?

    Dear all

    If a regular Diode is exposed to sunlight, generates voltage (like PV cell)? Why the circuit model of PV cell is a current source in parallel with a reverse diode?

    Jan-Martin Wagner

    Your question "Why the circuit model of PV cell is a current source in parallel with a reverse diode?" makes clear that there is a misunderstanding on your side: For regular operation, the diode in the standard equivalent model of a solar cell is always under forward bias; this you can see from the I--V curve under illumination. [Only in a partially shaded module some cells experience reverse biasing, and then (pre-)breakdown may occur.]

  • Neha Bansal added an answer:
    9
    For some series-connected PV cells, if one or some cells are partially shaded, they produce less voltage. Why does hot spot occur at this condition?

    For some series-connected PV cells, if one or some cells are partially shaded, they produce less voltage. Why hot spot occurs at this condition? Can you analyze the circuit both with/without bypass diode?

    Neha Bansal

    because the shaded cell is reverse biased by the entire power generated by non-shaded cells, due to insufficient dissipation of large amount of heat generated locally leads to hot spots in the module

    It is necessary to use 1 bypass diode for every 10 to 15 cells.

    Generally 2 being used for 36 series connected cells.

    because the shaded cell becomes load for the remaining, leading to very less or negligible current, you can simulate in matlab latest edition or in labview

    you can find very good papers on the shaded cell analysis on IEEE and Elsevier

  • Akram Abdulameer Abbood Al-Khazzar added an answer:
    3
    How Effect Of Air Mass On simulation of Solar parabolic dish concentraror?

    What value Air mass should be taken during the simulation of radiation in parabolic solar collectors and concentrating solar energy and receiver?

    (АM 1.5)?

    Akram Abdulameer Abbood Al-Khazzar

    air mass AM = 1/cos(zenith angle) as known

    for parabolic dish collectors usually the incidence angle is zero because of two axis tracking. 

    so u can neglect the effect of AM as I believe

  • Harsh Pandya added an answer:
    3
    How can I simulate Solar System With TRNSYS?

    - trnsys

    - simulation

    - Connection with output of first and input of the other

    Harsh Pandya

    Thank you so much for your answers...

  • Sachin Muralee Krishna added an answer:
    3
    What are the optimal dimensions of box solar cookers?

    length, height, width, isolation thickness

    Sachin Muralee Krishna

    The following article may be helpful to you.

  • Foued Chabane added an answer:
    13
    How can I convert Wh/m^2 to W/m^2?
    I want to calculate watt hour per square meter to watt per square meter.
    Foued Chabane

    - 1 Watt = 1 joule en une seconde
    - 1 KW = 1000 W
    - 1 MW = 1000000 W
    - 1 WH = 1 watt pendant 1 heure donc au total 3600 watts (3600 secondes)
    - 1 KWH = 1000 watts pendant 1 heures donc 3,6 MW (3600 * 1000)
    - 1 KWH/m2 = 3,6 MW sur 1 m2
    - 1 KWH/an = 3,6 MW sur une période de 1 an donc il faut diviser par 365 jours puis 24 heures puis 3600 secondes pour avoir les watts (moyenne généralement)

    Donc 1300 kwh/an = 4680 MW/an (1300 * 1000 * 3600)
    Donc 4680 MW / 365 jours / 24 heures / 3600 secondes = 148 W environ (moyenne indiquant les joules que l'on peut avoir en une seconde pendant un an)

  • Chunhua Shi added an answer:
    53
    How can we control fake data from our research journals. It will be really a great threat for scientific community in near future.
    Tokyo, June 29 (Jiji Press)–A Japanese anesthesiologist made up a total of 172 fictitious research papers between 1993 and 2011, an academic society said Friday.
    Yoshitaka Fujii, a 52-year-old former associate professor at Toho University, has denied fabricating research, according to the Japanese Society of Anesthesiologists.
    The number of papers that he allegedly faked is the largest ever for any medical researcher, both in Japan and overseas, according to sources familiar with the field.
    The society surveyed 212 articles written by Fujii that were published in a total of 41 Japanese and international journals. Of them, it found 172 fake research reports and three articles backed by real research. It was unable to assess 37 articles due to lack of scientific evidence.
    Coauthors of Fujii’s articles were not sure of the content of his research, the society said.
    Chunhua Shi

    Totally disagree John, Fake data  per se is a short term standing in the scientific society, but the person making the fake data may rob other scientist's opportunity in both career development and grant application. If they are successful in either career development or grant application, it will be a very bad demo to other people. 

  • Sheldon Feng added an answer:
    9
    Why is the stability of mesoporous perovskite solar cells better than the planar structure?

    The efficiency of organic-inorganic pervoskite solar cell is increasing rapidly, however the stability is a big issure. The device is extremely sensitive to moisture. For the device with a planar stucutre, 30 mins in air is enough to kill it. But for the device with a mesoporous structure, it could last a few days in air.  Just want to know the exact reason. Any clue will be appreciated.

    Sheldon Feng

    Azhar, thank you so much. You gave the convincing reasons. They do make sense!

  • Tony Maine added an answer:
    6
    What are the effects of storage devices in solar PV systems? Do they fully resolve intermittency of PV systems? Are they cost-effective?

    What are the effects of storage devices in solar PV systems? Do they fully resolve intermittency of PV systems? Are they cost-effective?

    Tony Maine

    A base load plant is capable of generating a steady amount of power regardless of the time of day. PV does not do this, though it could at a price with a lot of storage. As Alireza says, PV plants only work when it is sunny.

  • Samuel Tesema Lakew added an answer:
    7
    What kinds of modeling uncertainties exist in DGs?

    Hello,

    I would like to know what kinds of modeling uncertainties exist in DGs (Wind Turbines vs Solar Panels)? And which one leads to more accurate results?

    I look forward to reading your worthwhile answers.

    Regards.

    Samuel Tesema Lakew

    There are many uncertainties variables which can affect the feasibility of the solar/PV system. Some of these may be:

    1. Solar irradiation variation
    2. Solar panel price (if there is a replacement) variation
    3. Ambient temperature variation
    4. Load demand variation 
    5. wind speed and direction variation
    6. Converters replacement cost variation
    7. Battery (storage device) price variation
    8. inflation variation
  • Samuel Tesema Lakew added an answer:
    10
    How much is the at least irradiation for the photovoltaic panels?

    Hello;
    I want to know the minimum and maximum irradiation and temperature, which is necessary to operate the photovoltaic panels?
    thanks.

    Samuel Tesema Lakew

    As many of the researchers have suggested, it depends on the type of the PV panel. If you take the silicon PV cell panels, which are not efficient totally depends on the amount of irradiation available on a given area. As the resource is lower, at some point the panels stop generating power and you can say that point is the minimum range of the resource. But remember this value is not fixed for all PV cell types and for all places. If you take a more efficient PV like Nano Solar paint, they produce power  at very minimum irradiation.

  • Manuel Alberto M. Ferreira added an answer:
    12
    Do you think the nano-photovoltaic panels can be a good solution for problemes relating to electricity in remote desert regions? In which conditions?

    Have attention, for instance, that in these circomstances an energy source must be renewable, portable and easy to manage. Of  course, the costs must also be considered.

    Manuel Alberto M. Ferreira

    Dear Samuel,

    Thank you for your answer, so enlightening.

  • Hazem Ahmed added an answer:
    6
    Could anyone help us choose a suitable scattering coefficient and absorption coefficient for fluid and solid in a solar chimney?

    Dear Friends

    My team and I are working on simulation of a solar chimney. Using Solar chimney is a way to have a passive ventilation or producing power electricity. Solar Chimney contains a duct which covers with glass and have an absorb plate to get radiation heat flux from the sun.This plate warms the inlet air  by natural convection.By this method the air goes forward to top of the duct. Using this method could help you to ventilate rooms of a building which connected to this chimney or produce power electricity. The problem is choosing suitable absorb plate. In a lot of studies scientists choose Aluminum plate as absorb plate. Does any body know a better absorb plate.The other question is what's scattering coefficient and absorption coefficient for Aluminum as a solid and Air as a fluid in this special study ? 

    For more information I attached some pictures of solar chimney

    Best Regards

    + 1 more attachment

    Hazem Ahmed

    The scattering coefficient for a semi-transparent medium is zero, however, the absorption coefficient is a function of the wavelength, for example:
    for solar spectrum a= 10 1 / m...

  • Iqbal Hakimin added an answer:
    2
    Hi, can anyone explain to me the difference(s) between alloy and co-alloy, dope and co-dope, and the last one: co-association?

    I'm preparing a material (alloy) capable of harnessing solar energy and undergoing redox reaction of water. I'd appreciate detailed explanation.

    Thanks for the response!

    Iqbal Hakimin

    Thanks Dr. Bhaskaran, but I believe 'co' here doesnt refer to element cobalt, Co. From the article I read this could refer to 'cooperation'. I was guessing that co-alloyed would mean preparing an alloy that integrates both acceptor and donor at the same time. I just need someone to prove me right (or wrong).

  • Rajagopalan Raghavan added an answer:
    31
    How can two renewable energy sources interconnected?
    Eg. A solar array and a wind turbine are to be interconnected... Can they be connected directly in parallel or does some special arrangement have to be made while connecting them... Can both the sources work simultaneously?
    Rajagopalan Raghavan

    Parallel operation of Different renewable energy sources are possible and this is a basic requirement especially when we are talking of green energy and atmospheric pollution due to normal energy sources.   The decision on interconnection has tobe taken based on the grid to which these sources are getting connected and the impact of addition of these sources on the system.   Normally interconnecting at ac level could be conveniently adopted,

  • Dazhi Yang added an answer:
    10
    Does anyone know any publicly available collocated irradiance data on multiple tilts?

    This question is about datasets for irradiance transposition modeling. I am interested in datasets containing collocated irradiance measurements on multiple tilts (together with horizontal measurements). 

    Dazhi Yang

    Hi Bjorn,

    I have already sent you an personal email few days ago. Maybe you can check the junk mail box.

    dazhi

  • Samuel Tesema Lakew added an answer:
    11
    Is there any low price and high efficiency solar panel available?

    Is any low price and high efficiency solar panel available ? Solar panel is one of the renewable energy source material. But price little high now, any low price solar panel or other material available? is any research related to it? 

    Samuel Tesema Lakew

    Dear Sivanandam,

    Solar paint (made from nano scale solar cells with paint) is coming which is cheaper and efficient. check the link

  • Chris Gueymard added an answer:
    4
    How can I convert reference solar spectral irradiance at AM 1.5G (W m-2 nm-1) to the solar energy spectrum - number of photons (s-1 m-2 nm-1) ?

    I would like to calculate the theoretical photocurrent density can be obtained for photoanode. can anyone explain how to convert reference solar spectral irradiance at AM 1.5G (W m-2 nm-1) to the solar energy spectrum in terms of number of photons (s-1 m-2 nm-1).?

    Chris Gueymard

    The AM1.5G spectrum is obtained from the SMARTS model, v2.9.2. You can use it and select outputs in irradiance units, photonic units, or both.

    http://www.nrel.gov/rredc/smarts/

  • Anurag Pandey added an answer:
    2
    Can anybody give me information about gearbox and motors for solar tracking systems?

    I´m realinzing a proyect for the construction of parabolic trough collector system and I nedd the kind of motors and gearbox to implement the tracking system. I would be greatful if anybody could give information about providers or campanies where I can purchase it. 

    Anurag Pandey

    i found these papers related to solar tracking

    + 2 more attachments

  • Samuel Tesema Lakew added an answer:
    3
    In Hybrid wind-solar systems, do we interconnect the outputs at the DC side or AC side?
    Hybrid wind - solar energy conversion systems.
    Samuel Tesema Lakew

    There are two options to connect them to a common bus. But it depends wether the system is connected to grid or its own mini-grid (off-grid). The out put from PV is DC and should be converted to AC by inverter which at the same time levelize your voltage and frequency and you will directly connect the wind power to the AC link after the power is conditioned. OR, The PV DC power can also be connected to the DC link with the rectified power of the wind turbine. Is your system grid tied or...?

About Solar Energy

Energy transmitted from the sun in the form of electromagnetic radiation.

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