- Alain Fortineau added an answer:3What is the right amount of solar energy a plant needs to grow regarding light flux intensity, uniformity, PAR, IR, UV and how can someone measure it?
Apart from the PAR a plant needs some UV and IR, how much? (regardless of species). How can i measure if the light emmited from a source is right for plant growth(light flux intensity, uniformity, light distribution efficiency)
I'm not sure that UV and NIR are essential wavebands for plant growth. Nevertheless photons from those wavebands are detected by plantes. This ability allows plants to appreciate their environnement. These spectral signals are called MAR for Morphologically Active Radiation.
For exemple, red to far-red ratio (R:FR) is a signal which enables shade avoidance.
Review articles describe this mecanisme :
- Ballaré 1999, Keeping up with the neighbours: phytochrome sensing and other signalling mechanisms. Trends in plant science, march 1999. p97-102).
- Smith 2000, Phytochromes and light signal perception by plants — an emerging synthesis. Nature, october 2000. p585-59.
And blue light receptor has an action band between 350 and 500 nm (Morgan 1981, Non photosynthetic response to light, Physiological Plant Ecology).
You can caracterize spectra with a spectroradiometer (ADC, PP-system, Ocean-Optics).
If you already know the spectrum of your light source, you can use a Quantum meter (Li-cor, Solems ...).
I hope it will help you.Following
- Babu Bhaskaran added an answer:1Hi, 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!
Refer this link:https://www.quora.com/What-is-the-difference-between-a-composite-and-a...
Refer this link:www.aerodynealloys.com/.../cobalt/properties-composition-industries-co...
Refer this link:https://books.google.co.in/books?isbn=1615030700
Refer this link:https://books.google.co.in/books?id=O25VCgAAQBAJ
Refer this link:https://drugs-forum.com/forum/showthread.php?t=209346Following
- Muhammad Asim added an answer:1Would it make sense to do an LCA of a 1 MW Windmill and 1 MW solar plant to calculate its GHS's during production and EPBT?
I want to compare the two technologies to see which one is more sustainable.
yes,,it will be, because the potential is varying from location to location. it will will help to establish which technology is best for a specific location.Following
- Fernando Antonanzas added an answer:2How do I find the coefficients a,b,c in Donatelli & Campbell (1998) Solar Radiation Model can they be equal to the Bristow & Campbell coefficients?
Donatelli and Campbell model algorithm is similar in structure to the
Bristow and Campbell model so when using the Donatelli and Campbell model empirical coefficients a,b & c can we equate them to the location dependent empirical coefficients of the Bristow - Campbell model? I wasn`t able to find any relation for finding the Donatelli and Campbell model coefficients, a little guidance will be highly appreciated. Thank you
In general these classic parametric models need to be calibrated and validated in each location since most of them lack of spatial generalization. For a review of 24 of these parametric models I recommend this paper: https://www.researchgate.net/publication/258705095_Evaluation_and_improvement_of_empirical_models_of_global_solar_irradiation_Case_study_northern_Spain
Furthermore, I recommend that if you have a sufficiently long dataset you should calibrate the model doing bootstrapping (i.e. sampling 80% original of the original dataset and using it for training and repeating this 100 times) so you can evaluate how the parameters of the model and the errors of testing with unseen data would variate in case of calibrating the model with different data (this is also explained in the paper). You should choose the models with lower errors of testing but at the same with lower variation of validation errors and parameters (more robust models). For this training I used R free software (https://www.r-project.org).
Find attach an example with R (code.R and meteo.RData). For your case of study you should create a data.frame with your meteo data.Following
- Yasser A. Abdel-Hadi added an answer:4What is difference between total sky cover and opaque sky cover?
I need to estimate the actual solar radiation value from clear sky solar radiation data. So, I need to multiply the clear sky solar radiation by cloud cover. But I am not clear about total sky cover and opaque sky cover. Can anybody explain to me about this.
In surface weather observations, a term used to denote one or more of the following:
1) the amount of sky covered but not necessarily concealed by clouds or by obscuring phenomena aloft;
2) the amount of sky concealed by obscuring phenomena that reach the ground; or
3) the amount of sky covered or concealed by a combination of 1) and 2).
Opaque sky cover is the amount of sky completely hidden by clouds or obscuring phenomena, while total sky cover includes this plus the amount of sky covered but not concealed (transparent). Sky cover, for any level aloft, is described as thin if the ratio of transparent to total sky cover at and below that level is one-half or more. Sky cover is reported in tenths, so that 0.0 indicates a clear sky and 1.0 (or 10/10) indicates a completely covered sky. Amount of sky cover for any given level is determined according to the summation principle. The following classifications of sky cover are used in aviation weather observations: clear, scattered, broken, overcast, partial obscuration, obscuration.Following
- Tony Maine added an answer:4What should be the possible error of the model attach below regarding MPPT system for PV panel?
In my SPV system I am connecting a MPPT system to extract maximum power from the SPV system by changing the duty cycle of the buck converter. I think the model is working properly with 3 ohm (load) resistance, but whenever the resistance changes (say, 30 ohm) the power drown by the resistance (load) reduces. Can you suggest me the possible error of my model?
MPPTs are not magic! In practice they will work over a comparatively limited range of impedances. Let me explain. Buck converters work by allowing the generator to drive a load of lower impedance - but there is a limit. As the impedance of the load reduces, the currents in the convertor circuits increase, by a large amount. As you know, the power lost in a circuit varies as the square of the current, so reducing the impedance by ten times increases the current by ten times and the MPPT power loss by 100 times. At this point it is probably absorbing more energy than the PV system is generating. A boost convertor enables a generator to drive a higher impedance load than the generator, with the same limitations. As the impedance ratio increases, the power lost in the MPPT increases very rapidly, and the MPPT ceases to be effective.
In your case, you have a buck convertor, and this will drive loads of lower impedance than the PV system. Clearly a 30 ohm load is too much for it! To match a 30 ohm load it looks like you need to convert the PV voltage up, not down, and a buck convertor won't do that. If you want to drive loads of arbitrary impedance then use some sort of buck-boost convertor; but remember, the range of impedances they work over is not that large. 10:1 is a realistic figure for a real world convertor.
If you have to drive a 30 ohm load, reconfigure your PV system so that it can drive a 40 ohm load without the MPPT, then add the MPPT. If you want it to drive both a 30 ohm load AND a 3 ohm load, then accept that the reduced efficiency you get at either extreme may mean the MPPT simply isn't doing very much.
Good luck with your research!Following
- juan miguel Banez added an answer:3How can copper oxide be applied in solar cell technology?
I've read in some statements here that one of the applications of copper oxide is that it can be used for solar energy transformation, but how exactly is a nano particle used in such way?
Thank you very much Sir Sehgal & Sir Zekry. Your comments have been very helpful and enlightening. I hope you'd be open again in answering new questions if problem arises on our research. Again, thank you very much.Following
- Roberto Galleano added an answer:11Calculate solar radiation, received on inclined surfaces, based on horizontal data in different geographic locations?
Calculating solar radiation incident on inclined surfaces is a typical problem encountered in PV and building application. Is there a software tool which can be used to calculate solar irradiance for different tilts and orientations in different geographic locations based on horizontal data. If so, is it freely available? What are the literature which addresses above fact directly?
A very useful report on measuring and modelling solar radiation is this tech. report freely available from NREL: 'Best Practices Handbook for the Collection and Use of Solar Resource Data for Solar Energy Applications' Technical Report NREL/TP-5D00-63112 February 2015.
Moreover, an interesting site worth to visit is: http://re.jrc.ec.europa.eu/pvgis/
It is an online free solar photovoltaic energy calculator for stand alone or connected to the grid PV systems and plants, in Europe, Africa and Asia. It calculates, based on archived meteorological data, also the solar energy available at specific site for different inclinations.
- Mrinalini Padmanabhan added an answer:7Why are indirect semiconductors used as absorbers in solar cells despite their inferior absorption coefficient compared to direct semiconductors?How does the nature of the band gap (direct or indirect) affect the efficiency of a solar? Recombination processes must be different for solar cells made from these solar cells, how does this relate to the absorption properties of the absorber material?
Si is used as a Solar cell material even though it is an indirect band gap semiconductor. An indirect bandgap semiconductor requires a photon and a phonon to go form the valence band to the conduction band. This involves a change in energy( due to a photon) and a change in momentum (due to a phonon). There are other semiconductors like GaAs which are direct bandgap semiconductors, ie, they involve only a photon. This might seem like a more viable option as a solar cell material as compared to Si. However, Si has its advantages which as a whole works better as a solar cell material.
1. Si is abundantly available. It is the second most abundant element in the Earth’s crust (about 28% by mass) after oxygen. So, it is very cheap.
2. Ge is also an indirect band gap semiconductor, however, the surface passivation is easier for Si as compared to Ge.
3. GaAs is very very expensive. So, it is generally used in multilayer concentrated solar cells where mirrors and reflectors are used to concentrate light on the cell of smaller area. The efficiency of this cell is maximized by the use of mirrors which add to the cost of the cell. These cells are used as space solar cells.
Keeping these reasons in mind, Si is used as a solar cell material.Following
- George Loumakis added an answer:2Which polymers can highly absorb solar energy and what are their properties?
Which polymers can highly absorb solar energy and what are their properties?
Are you interested in polymers for solar thermal applications? If so i would say looking at engineering grade plastics would be your best bet. Apart from that Microcapillary films of low density polyethylene have heat transfer performance similar to metal based micro scale heat exchangers. Perhaps looking into carbon black fillers would be of use as well.Following
- Vincenza Liguori added an answer:10Do 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.
Dear Manuel Alberto M. Ferreira,
Thank you very much for your appreciation.Following
- Pablo Daniel Bonaveri added an answer:3Can any one give information on "reserve cost function and penalty cost function for Solar power" for application in economic dispatch problem?
Any paper that gives information on reserve cost and penalty cost coefficients for solar energy.
A Dynamic Economic Dispatch Model Incorporating Wind Power Based on Chance Constrained Programming. Wushan Cheng and Haifeng Zhang. Energies. ISSN 1996-1073. 8, 233-256; doi:10.3390/en8010233. http://www.mdpi.com/journal/energies.Following
- Parthasarathy Srinivasan added an answer:5Why do we prefer using TiO2 in dye sensitized solar cells?I am new in solar energy materials and I was going through DSSC. I haven't figured out why we use titanium oxide as a charge collector.
since TiO2 is more stable and moreover the electron drift is maximum as far as the transport of the charge is concerned..Following
- Kwei Kwang Chang added an answer:9Can someone tell me how the Vacuum Wavelength/Frequency of sunlight can be related with weather fluctuations of a particular day?
I am modelling solar dish collector in COMSOL. I want to redo my model for various weather conditions i.e., Hot sunny, cloudy, cold sunny days with and without clouds.
Apparently I can vary the Vacuum wavelength or frequency under ray properties. Can anyone please tell me some empirical values for such different weather conditions and also for different parts of day.
Default value of COMSOL is 660 nm and 4.54e14 Hz.
Any help in this regard will be highly appreciated.
Thanks a lotFollowing
- Oswaldo Lopez Santos added an answer:5What are different control (decision) variables of maximum power point tracking (MPPT) systems in PV's (other than duty cycle of boost converters)?
What are different control (decision) variables of maximum power point tracking (MPPT) systems in PV's (other than duty cycle of boost converters)?
The more simple way to control a DC-DC converter to perform MPPT requires the measurement of the current and voltage of the PV module (Ipv and Vpv) in order to estimate the required value of the duty cycle D (Using PWM with constant frequency). Another way to perform MPPT is obtained by using a hysteresis comparator to control the DC-DC converter through is input conductance (G) having that G=Ipv/Vpv, in that case the same measurements are required.
Yo can see details of an approach of this kind of methods in my Ph.D. thesis entitled "Contribution to the DC-AC conversion in photovoltaic systems: Module oriented converters".Following
- Jethro Betcke added an answer:18Why is quality of life limited by EROI with renewable Energy?
There are many articles explaining that the Energy Return on (Energy) Invested (EROI, or EROEI) of the sources of energy which a society uses sets an upper limit on the quality of life (or complexity of a society) which can be enjoyed (for example http://www.sciencedirect.com/science/article/pii/S0301421513006447).
I understand the arguments made, however I fail to understand why any energy extraction process which has an external EROI greater than 1.0 cannot be "stacked" to enable greater effective EROI.
For example if EROI for solar PV is 3.0, surely one can get an effective EROI of 9.0 by feeding all output energy produced from one solar project as the input energy of a second?
There is obviously an initial energy investment required, but provided the EROI figure includes all installation and decommissioning energy requirements I don't understand why this wouldn't work. Also I realise there are various material constraints which would come into play; but why does this not work from an energy point of view?
@Charles Hall: You make some statements that are somewhat inaccurate and could easily mislead the less well informed:
Windturbines produce electricity during 70 to 90% of the time. You seems to have confused capacity factor with relative time of operation.
Using a single number for the capacity factor is also not so accurate. Depending on the location and design choices the capacity factor can vary from 20% to over 50%.
With the lifetime of PV systems you seem to have confused the inverter with the system as a whole. The practice has shown that PV modules last much longer thatn the 25 years garantueed by the manufacturer. In Oldenburg we have a system from 1976 that is still producing electricity and shows little degradation loss . Inverters are the weak point of the system and sometimes need to be replaced. Ofcourse, this would need to be considered in an EROEI calculation. But this is something different than what you state.
- Diego García-Gusano added an answer:7Where can I access trend data on solar LCOE for Europe?
I am looking for data on solar levelized cost of energy. I have US data. I am looking for Europe from 2009-2014. Is there anything available on the public domain? Most of the IEA/IRENA reports seem to be reporting for just one year or two. I am looking for trend data.
This study from ISE-Fraunhofer is very relevant:
- Bailek Nadjem added an answer:26How to calculate monthly average daily extraterrestrial radiation on a horizontal surface? (please see the attached file and guide me)Please see the attachment for detail
Assistant can explain the details of the work
I want information /latitude of sit
e mail firstname.lastname@example.orgFollowing
- Ken Schatten added an answer:12Where I can find good sunspots and cosmic rays data in the equator area ?
I'm from Indonesia and need good sunspots and cosmic rays data in equator area for my thesis. Please help me, where I can find that data ?
The clette svalgaard, etc data are excellent for a long term proxy indices,
For direct measurements, you should look at NOAA's SWPC space weather prediction center, where they have the data stored with explanation of what they are.
Typically when you ask for this kind of data, there is not taken to be any location based data. they are global data. If you want to figure out how it affects your area in particular.
The "viewing angle? for sunspots can make a difference, as well as for cosmic
rays.. There is the south atlantic anomoly which affects cosmic rays (at the lower energies..
They also have a staff which can help you..
best wishes, kenFollowing
- Muhammad Asim added an answer:9How much is the at least irradiation for the photovoltaic panels?
I want to know the minimum and maximum irradiation and temperature, which is necessary to operate the photovoltaic panels?
@k.sudhakar, thanks for your input. could you please provide the reference for this data.Following
- Edgars Alksnis added an answer:3How can we calculate the mouthly average of solar zenith angle in Jule in London(51.518°N, 0.128°W)?
Such as in Jule in London(51.518°N, 0.128°W)? (daytime)
Yes. There are astrological programs also, of course.Following
- Manikandan S added an answer:6What would be an efficient dc motor which can be used for solar tracking system?
I need to rotate a solar panel of 1kg weight to both clockwise and anti clockwise direction.
You can use wiper motor. It have enough torque. It is cheaper, easily available and use can use simple H-bridge to run it.Following
- Prashant Ghediya added an answer:5What is the expected influence of sodium incorporation in Cu2ZnSnS4 optical properties (Raman and Photoluminescence)?Could anyone point out the effect of sodium incorporation on the optical properties of Cu2ZnSnS4 (CZTS) especially something meaningful that can be observed by photoluminescence spectroscopy or Raman spectroscopy?
I am also working on CZTS. Recently, I tried to doped CZTS by sodium. However, XRD shows high crystalline intense peaks of sodium along with CZTS. The films were heated at 200 to 400 C in air for 1 hr. The literature claimed that Na doping not only improved the morphological properties but also enhances the electrical and photovoltaic properties of the CZTS films. But, I haven't observed any significant effect of Na. Could you please, suggest methodology of incorporation of Na. How can i remove sodium peak?Following
- Alexander Brem added an answer:3Can anyone suggest literature on Regional Innovation Systems in solar energy in the Indian context?
I am looking for literature on RIS in solar energy/PV in the Indian context.Following
- Tony Maine added an answer:13Can I use the three diode model to simulate the physical behavior of any pv module?
Can i use the three diode model to simulate the physical behavior of any pv module? Edit
can i use the three diode model to simulate the physical behavior of any pv module , or there are any restrictions on using this model . if there are any restrictions what are they? why?
three diode model is valid to simulate the physical behavior of any pv module, or restricted on certain types of pv cell
Abdelhalim's answer is very thorough and impressive. I have used various models to simulate dye sensitized solar cells with interesting results. It depends very much what you want to use the simulation for. Don't forget in the real world, manufacturing tolerances and variations in the weather and sun position totally mask any minor variations you might get from adjusting internal cell parameters. On the other hand, if you are researching the cells themselves and maybe comparing technologies, then a simulation approach using diodes is essential.
Simulating large arrays, I found the best way to handle these is to simply measure a batch of cells, derive typical responses for the ranges of solar input and applied voltage and plug the numbers into a multidimensional lookup table. Then you can simulate large arrays with some confidence.
Best wishes with your work!Following
- Dalia Arafa added an answer:4Ask about if the three diode model is valid to present any pv device?
i want to know if three diode model can present any pv module or restricted only for certain types of pv cell (cell only ). and why?
please dear Trung-Kien Vu ·
clarify what you want to say, if three diode mmodel is valid for pv module like pv cell or not and why ?
- Afshar Shaikh added an answer:6How might I estimate the size of a solar power system and power generation at different temperatures for offshore rigs? Provide calculation methods.
Please provide offshore case studies or calculation methods. Appreciate your help.
Thank you for information provided. Can you pls share the link of paper ?Following
- Sergio Andrés Sánchez-Sanjuán added an answer:8I want to learn the fundamentals of solar cells in general and perovskite solar cells in particluar. Is there any review paper or book regarding this?
Basically, I want to start from scratch and learn all the concepts related to solar cells.
I share you this link of book with some fundamentals conceptos about solar cells and their characterization in spiceFollowing
- Wei E. I. Sha added an answer:11What's the major challenge of perovskite solar cells?It is such a hot topic these days. What's the major challenge in this field? Is it really going to be a mainstream technology?
you can read my paper in http://dx.doi.org/10.1063/1.4922150. I also edit wikipedia for perovskite solar cell (physics part).Following
About Solar Energy
Energy transmitted from the sun in the form of electromagnetic radiation.