- Engr.M Imran A Chowdhary asked a question:NewIs there any helping material about hybrid piezoelectric Photoelectric Penal?
PV cells are good renewable energy source but in rainy condition there should be any source of energy. Piezoelectric crystal sheets are good source of electricity in rainy conditions, because it generates electricity by applying mechanical stress.Following
- Ana Gabriela Galicia asked a question:NewI'm looking for the "n" and "k" values for InGaN to modeling a solar cell in Silvaco Atlas. Does anyone can share this data?
I've already tried to use Adachi's model but for some reason, it doesn't work on my simulation. When I plot the results for the imaginary index, it's zero.
Does anyone have an idea to get data with this model using Atlas?
Or have the values for "n" and "k" to input in an ASCII file directly?
- Tharakeswar Dommaraju added an answer:5What are the effects of p-substrate parameters on the performance of Si solar cells?The silicon solar cell is composed of a p-substrate and an n+- emitter. In this forum I wish to discuss the effect of the substrate parameters on the performance of solar cells.The parameters of interest are the thickness of the substrate, the minority carrier lifetime, the doping concentration and the back surface field. The parameters of the solar cells are the photocurrent, the reverse saturation current, the open circuit voltage, and the conversion efficiency.
To Trygve Mongstad:
Sir both the links you have given are not working. It's saying that the files has moven. can you please give the new links.Following
- Wang Xiaoliang added an answer:9How can I analyze stability for solar array, DC DC converter, and battery system?
Say we got a solar array which supply power to battery through a DCDC converter. We want to design two control loops for the converter.
One is the inner(fast) loop which regulates the converter output voltage or current. This loop can be analysis by the traditional converter small signal model.
Another one is outter(slow) loop which is regulate the converter input voltage or current (solar array output voltage or current). How can we analysis the stability for this loop? Do we need to include the small signal module of solar array? If the voltage or current is regulated by some algorithms, how to model the algorithm?
Any tips would be very helpful, thank you
Thanks for your answer. The difficulty part is we want to know the TF before we building the hardware.Following
- Vadiraj K T added an answer:7Which is the best light source to construct solar simulator?
I am building solar similator at my laboratory. I used tungsten source which is giving only 12000 lux. I am looking for a source of 100,000 lux or so. Please suggest me.
it a single layer cell, With a polymer and Metal sulphide blend. Coated on ITO glass and Aluminium back coat.Following
- Waseem Raja added an answer:3Charge transport in Perovskite solar cell?
Could you please tell me the best reference article on charge transport of perovskite solar cell including the charge mobilities and recombination rates values as well?
- Sundeep Kumar Dhawan added an answer:4Which is the best carbon material for counter electrode in Dye Sensitized Solar Cell?
I have researched counter electrode for DSSC application for several months, which is the best carbon material for counter electrode in DSSC?
Now a days, graphite is no longer used. Previously graphite was the electrode of choice.Following
- Shruthi Jayadev added an answer:13Is it possible to improve solar power yield by providing water cooling on the back side of solar panels using copper tubes?
The back side of the solar panel is insulator. But recently I have read some papers which indicate that by providing aluminium fins on the back side of solar panel temperature of the panel can be brought down, thus improve the power yield. If air cooling can improve the power yield even by fraction of percentage, water cooling will yield much better results. But will it be possible to bring down panel temperature from insulator?
I have fabricated cooling structure using for backside of photovoltaic panel. however, I found that non-cooled panels gave higher power output than cooled panels. So my conclusion was that may be instead of absorbing the heat from panels, copper tubes are trapping the heat.
I further welcome any suggestions for water cooling structure to improve power yield.Following
- Santhosh Kotni added an answer:1What is the best method to estimate the QD concentration or excitonic concentration per unit area in a thin semiconductor film?
What is the best method to calculate the number of QDs in a QD sensitized solar cell. What is best method to estimate number of excitons in a QD sensitised solar cell.
Measure the absorption spectrum of the thin film, and get the value of first exciton band maximum. Once you know the wavelength of the band first exciton band position, following certain equation in the below link, you can arrive at the QD concentration. But I have to mention here that, the equations are only for CdS, CdSe and CdTe.
- Rajendra Kumar added an answer:2If we are using ITO substrates for perovskite solar cells, what is the suitable annealing temperature for mesoporous TiO2 crystallization?
In FTO substrates, the annealing temperature for mesoporous TiO2 crystallization is around 450 to 500oC for 30 minutes. But if we use ITO, we can not anneal above 300oC. It may increase the resistance of ITO. What is the solution for this problem?
Please share your views.
Thank you for your valuable comments.Following
- Islam Mansour added an answer:3Is there any direct approaches to derive the diffusion coefficient from open-circuit voltage or short-circuit current density?
What we have are Voc and Jsc . We know D can be expressed in:
where, L is diffusion length, D is diffusion coefficient and t is carriers life time
where, J is current density from diffusion, q is elementary charge, (dn/dx) is charge carriers density gradient.
in some expressions like the following expression, we already must clarify some factors like, G(generation rate) to get the correct diffusion length:
Voc=2kT/q Ln(GLt/ni )
kT : product of Boltzmann constant and temprature
GL : Generation rate
ni : Intrinsic density of charge carriers
Therefore, using this expression, we would not be able to approach directly to the diffusion coefficient!
Thank you Prof. Zekry for your nice and detailed answer.Following
- Ahmed T. Elsayed added an answer:15Is there a microgrid with inductive line impedance (X>>R)?
I have work on microgrid area and microgrid voltage and frequency control. there is a contradiction for me about selecting the line impedance type (R>>X or X<<R) in my microgrids. I was read several credible paper (IEEE Transaction index) about microgrids that in these paper Is mentioned that " the line impedance in microgrid can be consider both R>>X or X>>R. also in this paper, there is an explane about voltage and frequency control in inductive microgrid (X>>R).
also, I was read some article about microgrid that these papers said that the microgrids have resistive line impedanc.
now, I wana to know that, really is there a microgrid with inductive line impedance according to the credible paper of IEEE that I attached for you?
The lines connecting DG units are not so long as you may imagine, they are relatively long compared to that within the microgrid. Some DG units are equipped with transformers or boost converters.Following
- 4What are the factors which limite overheating of single cell in PV-battery?
In discussions about "hot patches" and OC- SC-operation modes in
PV-batteries those participants said:
Ioannis john Tsanakas noticed:
It is known that when a PV module is short-circuited, its thermal image temporarily shows a pattern, with some cells apparently more warmer than others.
Anton Driesse explained:
Cells with a higher Isc.cell must operate at a positive voltage to
reduce their current, and cells with a lower Isc,cell must operate at a
negative voltage to increase their current. The sum of all the voltage
drops is zero, so no electrical power leaves the module. However the
individual cells with positive voltage drops will generate power that is
dissipated in those that have negative voltages.
Henri Cloetens explained:
This voltage distribution causes a net flow of energy from the cells
with positive voltages, to the cells with negative voltages. And that is
what you see.
I agree with these explanations. They help to explain the temperature
anomalies in electrically identical batteris.
My previouse qustion is:
Can anybody explain why the temperature are different on two identical
solar PV-batteries for SC- and OC-mode?
My next question is:
My experimental PV-batteries have 36 elements in serial, without any
blocking diode for reverse current. So in SC-conditions the 35 elements with positive voltage produce additional power for the single weakest element with negative offset. This will lead to non-realistic strong overheating of this single weakest element. But real thermal image consist of numerous (not single) hot patches with restrained overheating.
What factors limite overheating of single cell in PV-battery?
Let us think about what is happening here.
A PV panel is illuminated with solar energy, 80% of which is converted into heat and 20% into electricity. If there is a way for the electricity to exit the panel and deliver energy to an external load, it is the external load that gets hot instead of the panel.
If the external load is a short circuit or open circuit, the electrical energy does not exit the panel but remains in it and heats it up, just as if it had not been generated at all, that is, as if all the solar energy had been turned directly into heat.
The only difference is that under short circuit conditions the electricity can circulate inside the panel and heat the cells slightly unevenly depending on their electrical characteristics. The difference in electrical heating between different cells might be 1 or 2% of the total thermal energy dissipated in the panel.
It really isn't worth worrying about!Following
- B. Bindhu Krishna added an answer:3Can you please suggest methods to synthesize graphene quantum dots that have visible and /or NIR absorption?
I want to fabricate graphene quantum dots for solar cell application. But, I could not get a suitable method for synthesizing these graphene quantum dots that have VIS and /or NIR absorption? I will be happy if you send me published research articles on this area.
Highly ordered graphene quantum dots can be synthesized through microwave and hydrothermal method. Pls look at the attached article. U may find it useful.Following
- Jephias Gwamuri added an answer:15What kind of contact materials should I use for back contact a-Si:H solar cell?
We use the Al back contact but it's not suitable because Al has very bad adhesion to a-Si:H.
@Igor. I am glad you found the info helpful. Let me know if you need more info.Following
- Amr Hessein added an answer:12Can anyone tell me the procedure for Electrochemical Impedance Spectroscopy (EIS) of symmetric cell?
I working on developing a counter electrode of sensitized solar cell based on graphene. And I need to perform EIS of these electrodes. In the literature, the authors perform EIS of cells consist of two symmetric electrodes. So I would like to know if anyone can tell me the procedure of this test or there is a reference containing the details of this type of tests?
first,I disperse Graphene based powders in NMP with 10% PDVF as a binder. then I use drop casting method to coat FTO with this dispersion. the area is defined by adhesive tape.Following
- Sai-Anand Gopalan added an answer:21How can I dissolve 0.8 M PbCl2 : 2.4 M MAI in DMF solvent?
I am trying to dissolve PbCl2 (99.999%) and MAI in DMF solvent, I left the solution overnight at 70 deg C and used magnetic bars for stirring. I believe that PbCl2 doesn't fully dissolve in DMF and it gives me yellowish murky solution.
I tried a bunch of things suggested elsewhere on RG:
1) To increase the hot plate temperature and play around with stir-plate rpm.
2) Pulverize the PbCl2 crystals.
3) Dissolve both PbCl2 and MAI separately in DMF.
4) Change the concentrations.
All the above trials would still end up giving the same murky solution. Although the device parameters and PCE is very decent, I am still interested in obtaining a clear solution.
Quite interestingly, the people at Alfa Aesar are not fully convinced that PbCl2 would dissolve in DMF. We shared some papers (Snaith's group) with them and they are still not convinced. But they hinted that changing the solvent (Dimethyl sulfoxide) might solve the problem.
Any suggestions to obtaining the clear solution is much appreciated. Thanks!Following
- Sai-Anand Gopalan added an answer:8In the two-step synthesis of perovskite solar cells, why does the perovskite layer go off (evaporates) after removing from CH3NH3I-Isopropanol soln?
Two step methods consist of,
1) spin coating PbI2-DMF solution (462 mg/ml) on substrate and then annealing to form PbI2 layer
2) dipping the PbI2 coated substrate in CH3NH3I- Isopropanol(IPA) Solution (10 mg/ml) to form brownish CH3NH3PbI3 coating
The problem occurs after removing substrate from 2nd step. The IPA evaporates off immediately leaving behind whitish patches, thus damaging the base layer too.Following
- 16Can the fill factor value of a solar cell be greater than 1?
Also what does FF of a solar cell actually mean?
when i am calculating FF from cell iv plot it has value greater than 1. Why it is so..tell the correct procedure for the calculation of FF.
There may be a slight misunderstanding! Of course no conventional solar cell will possess negative output impedance - that would be indeed thermodynamically impossible as Dr Wagner points out. I am being - for a change - rather theoretical, saying that any generator which possesses a negative output impedance could possess a fill factor greater than unity. That is a generalised statement. I apply it to a solar cell because it is general, not because any existing solar cell would operate like that. However, it may be possible to construct a solar cell with some sort of built in voltage regulator or other similar mechanism, and such a cell, if it's parameters were set incorrectly, could demonstrate negative output impedance.
But, really, I don't think it is very practical suggestion, and definitely not something we should worry about!Following
- Amol Chintaman Badgujar added an answer:7How do I synthesize a Al2O3 Scaffold layer for the hybrid Perovskite thin films for solar cell applications?
Inorder to increase the perovskite film efficiency some papers discused about Al2O3 scaffold layer but they haven't discuss about its preparation method So please suggest me the method of preparing and coating Al2O3 Scaffold layer over perovskite layer to get hybrid perovskite films.
Thank You ...
Dear Selva Kumar
Please watch lecture by Prof. M. A. Green about emergence of perovskite solar cells.
It will give you better idea.
- Maie Fadel added an answer:10How do you dissolve polyethyelene terephthalate (PET)?
I'm trying to dissolve PET to make a film out of it. I'm having a hard time finding good solvents and procedures online and would appreciate any help I can get.
i dissolve it in 1,1,1,3,3,3-Hexafluoro-2-propanol. and i get a good filmFollowing
- Muhammad Ayaz added an answer:3Can someone suggest some research about dye sensitized solar cell?I have an idea to make a solar cell with natural dye as dye sensitized. Could anyone with experience share their knowledge with me?
AoA Take fresh Gnetum gneom wash with di-water and dry in room temp.Than graind it and put into ethanol and place in dark room for one week.After that filterout and use extract over DSSC.Following
- 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
- Dan Credgington added an answer:5How are electron-hole pairs generated in perovskite solar cells? Why are electron and hole transport layers needed?
From the basics, I know that solar cell is nothing but a p-n junction where light falls from the n side. From the literature review I found no such p-n junction in perovskite solar cells rather electron transport material, perovskite and hole transport material. What is the role of these transport layers?
Please help me with the proper concept. Thanks in advance
Just to add to the explanations posted above, it's generally observed that polycrystalline perovskites like MAPbI are much more like conventional crystalline semiconductors than molecular semiconductors. That is, they exhibit true delocalised conduction and valence bands (rather than HOMO and LUMO levels), are relatively defect free (see attached) and it's generally agreed that, at least for the Iodides, the exciton binding energy is lower than kT at room temperature. This means that no heterojunction is needed to split excitons, they will dissociate spontaneously, which also explains why thick perovskite films make perfectly good solar cells.
Your question is therefore a very good one, what is the role of the transport layers? The key principle is that a solar cell needs selectivity - there must be some reason for electrons to drift/diffuse out of one side of the device rather than the other. For doped semiconductors, the p-n junction fulfils this role. Since perovskites cannot yet be doped in a controlled manner, the alternative is to make the contacts electron- or hole- selective by introducing different materials (as is done for dye cells) which preferentially extract one carrier type. In some cases, this also leads to the creation of a built-in field. In this way, they are indeed similar to a p-i-n junction, though the presence of mobile ions will complicate the internal field structure.
Hope that helps,
- Maqsood Ali Mughal added an answer:3Is indium sulfide an indirect bandgap material or direct bandgap material? or both?
The bandgap reported for indium sulfide whether it is direct or indirect is still controversial. Anybody shed some light upon it?
Thank you both. However, there are also papers who reported direct bandgap of 2.9 eV for indium sulfide thin films, which leads to confusion whether it is a direct or indirect bandgap material.Following
- D.B. Jani added an answer:2How can I define a model of the solar parabolic dish collector in TRNSYS 17?
how to define a model of the solar parabolic dish COLLECT in TRNSYS
Please go through the following link for further details of simulation
- Santo Martinuzzi added an answer:4Why is the Jsc of tandem solar cells are typically lower than Jsc of the subcell that produces lower current?
I have read several papers about (organic) tandem solar cells, in some papers Jsc of tandem cell is almost equal to Jsc of the subcell that produces lower current and in some of papers Jsc of the tandem cell is lower. Which parameters cause lowering the Jsc of the tandem cell compared to the Jsc of subcell with lower current?
The tandem cell is a complex structure in which the subcell is not illuminated like in real sun. There is certainly a loss of current due the spectral mismatch. In additionThe optical (antireflection coating) is certainly modified and the surface passivation of the subcell is not so efficient like in an individual cell. Endly, the illumination level is low and in some matrials the lifetime of minority carriers decreases with this level (except for n-type silicon). As a consequence the photocurrent density is also lower than in an individual cell. Obviously, sun light concentration is a partial solution to the preceding problems. Endly, the considerations of AbdelHaim Zekri concerning the equivalent electrical circuit of a tandem cell must be taken into account.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
- kamala kanta Nanda added an answer:4How do I solve the problem of continuous corrosion of metal sulfides counter electrode in the presence of polysulfide electrolyte?
my counter electrode for the quantum dot sensitized solar cell made from nickel sulfide. In the presence of polysulfide electrolyte, the counter electrode dissolving and contaminating the working electrode which destroying the performance of the solar cell.
Did any one has an idea to solve this problem?
The link to the paper is