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(/* The influence of dye structure on charge recombination in dye-sensitized solar cells J. R. Jennings, Y. Liu, Q. Wang, S. M. Zakeeruddin, and M. Grätzel, “The influence of dye structure on charge recombination in dye-sensitized solar cells,” Phy...)
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<center>This is a literature page for project [http://www.appropedia.org/Pyranometer_project_2014_spring pyranometer in 2014 spring]</center>


= Implementation of an Economic System to Measure Solar Radiatio =
== Review ==
== Authors ==
=== Quantum dot solar cells<ref>[http://www.sciencedirect.com/science/article/pii/S1386947702003740 A. J. Nozik, “Quantum dot solar cells,” Physica E: Low-dimensional Systems and Nanostructures, vol. 14, no. 1–2, pp. 115–120, Apr. 2002.]</ref> ===
Mohamed Darwish, Omar G. Angulo Castro, Ricardo Valenzuela, Alejandro Ortega, Gildardo Jimenez
[http://www.sciencedirect.com/science/article/pii/S1386947702003740 A. J. Nozik, “Quantum dot solar cells,” Physica E: Low-dimensional Systems and Nanostructures, vol. 14, no. 1–2, pp. 115–120, Apr. 2002.]
== Abstract ==
<br /><br />Background:
A data acquisition system based on a pyranometer, data acquisition board and a computer to record and display the data are developed
[http://www.siliconfareast.com/hotcarriers.htm Hot carrier and impact ionization]
Pyranometer based in solar cell, National Instrument USB-6008 as data acquisition, LABView as interface system. Made this a considerably cheap system.
Hot carrier @ solar cells: Electrons/holes receives photons with energy much higher than their band gap will carry kinetic energy create effective temperature much higher than lattice temperature (3000K of carrier @ 300K of lattice etc.). Primary loss for this:
The pyranometer was physically located on the top of the roof, reading was taken every 30 minutes during 33 days in January, March, April and May (why not Feb?), no night readings. All measurements from 6:00 am to 6:00 pm. Location at 31.19’07’’N and 110.56’45’’O, 1000 meters above sea level.
*Heat through scattering (KN is transferred into band vibration?)
Result shows a reading error within 7%  and above 2%.
*Photon emission (electrons occupied holes to let out photons?). Approach to stop this loss:
*Stacked cascaded multiple p-n junctions to match multiple band of solar spectrum. This reduce carrier relaxation via photon emission.  Efficiency increase to 66%. 
*Reduce thermal relaxation – utilize hot carriers before their relaxation.
**Enhanced photo-voltage: being extracted before cooling; Requirement: transportation of hot carriers faster compare to the cool down rate – which should be related to the material itself.
**Enhanced photo-current: create second or more electron-hoe pair(s) by impact ionization (Auger effect: one electron hit a band create one e-h pair. What will happen to this electron?); Requirement: impact ionization rate faster compare to the cool down rate & e-h pair transport rate faster than cool rate?.
**Quantization confinement will dramatically reduce hot carrier’s cooling rates. (So this confinement will also reduce the cool down rate in Auger process which is not desired?)
*What about some part of solar spectrum is absorbed to stimulate electron from En to En+1 or higher and the left spectrum will cause these electrons to emission from En+1 to En-1 to let out more photons with same lambda. Then one layer will be used to specifically to absorb these electrons.
Hot electrons and hot holes cool down rate are different because:
*Mass difference (Which one is faster?)
*Hot carrier cool rate depends on density of photo-generated hot carriers (How this makes diff?).
Predicted way for QDs: hot electrons with slowed cooling rate in QD --- Auger process, fast cool down hole due to mass & closer quantized space --- photo-currents. Bottleneck due to fast hole trap at the surface will slow cooling rate (7 ps at CdSe, InP QDs compare to 0.3 ps cooling rate without hole trap). This will prevent Auger process.
<br />Suggested Syetems:
*QD arrays in p-i-n cells. (Quasi-1D system)
**Advantages:
***Delocalized quantized 3-D miniband states might slow the carrier cooling rate to allow hot electron transportation and collection.
***Impact ionization can occur, however not in the same time with hot electron transportation/collection.
**Fabrication:
***Colloidal
***Epitaxial
**Challenge:
Disorder of shape, surface state etc.
*QD sensitized DSSC (Dye-sensitized solar cell)
**Advantage:
***Tunability of optical properties with size of QDs.
***Quantum yield might be greater than 1, meaning one photon might generate more than one electron-hole pairs.
**Fabrication:
Absorption from QD colloidal.
*Quantum dots dispersed in organic semiconductor polymer matrices.
CdSe QDs are formed in hole conducting polymer. Structure of QDs affects the efficiency. Different layers can be applied to conduct electrons (TiO2) or holes (MEH-PPV). Challenge: electron-hole pair might recombine in surface of polymers. Refer to [http://onlinelibrary.wiley.com/doi/10.1002/(SICI)1521-4095(199908)11:11%3C923::AID-ADMA923%3E3.0.CO;2-T/pdf CdSe Nanocrystal Rods/Poly (3-hexylthiophene) Composite Photovoltaic Devices] for rodlike CdSe QDs structure. Refer to [http://physics.ucsc.edu/~sacarter/alexi_399.pdf Charge transfer in photovoltaics consisting of interpenetrating networks of conjugated polymer and TiO2 nanoparticles] for multiple polymer structure.


= Solar Irradiance Estimation Based on Photovoltaic Module Short Circuit Current Measurement =
== Authors ==
Rodney H.G. Tan, Priscilla L.J.Tai, V.H. Mok
== Abstract ==
This paper using the estimation method of solar irradiance based on the short circuit current output produce by the photovoltaic module. Paper trying to prove the feasibility of this method with desired accuracy. Paper introduced Photovoltaic Module Model as a circuit model, according to the property of its solar cell diode, derived the relation between short circuit currents and the solar irradiance leads to this. By acquiring the datasheet for solar cells diodes from their manufacturers, parameters for this relation can be derived using mathematical models. By considering these parameters, the solar irradiance can be estimated.
However, the result shows that the highest error can reach 15.9%, making this estimation not a very ideal method for high accuracy applies but only for rough estimation while expensive measure device like pyranometers are desired.


= PV-based Li-ion Battery Charger with Neural MPPT for Autonomous Sea Vehicles =
=== CdSe Nanocrystal Rods/Poly (3-hexylthiophene) Composite Photovoltaic Devices<ref>[http://onlinelibrary.wiley.com/doi/10.1002/%28SICI%291521-4095%28199908%2911:11%3C923::AID-ADMA923%3E3.0.CO;2-T/abstract W. U. Huynh, X. Peng, and A. P. Alivisatos, “CdSe Nanocrystal Rods/Poly(3-hexylthiophene) Composite Photovoltaic Devices,” Adv. Mater., vol. 11, no. 11, pp. 923–927, Aug. 1999.]</ref> ===
== Authors ==
[http://onlinelibrary.wiley.com/doi/10.1002/%28SICI%291521-4095%28199908%2911:11%3C923::AID-ADMA923%3E3.0.CO;2-T/abstract W. U. Huynh, X. Peng, and A. P. Alivisatos, “CdSe Nanocrystal Rods/Poly(3-hexylthiophene) Composite Photovoltaic Devices,” Adv. Mater., vol. 11, no. 11, pp. 923–927, Aug. 1999.]<br /><br />
M. C. Di Piazza, M. Luna, M. Pucci, G. Vitale
Important factors affect the performance of a PV device includes:
== Abstract ==
*Overlap of the absorption of solar spectrum;
Photovoltaic battery charger based on a DC-DC boost converter for a small size marine autonomous vehicle is developed. Neural-based technique is used to estimate the solar irradiance on the basis of the actual PV panel voltage and current to provide maximum output. This techniques is called Growing Neural Gas, and is exploited to realize a virtual Pyranometer to acquire instant solar irradiance. The GNG network is a self-supervised system to create best topology for the vehicle. GNG then is trained to learn data by experiment, and then recalling these by online calculation to estimate the irradiance. On the basis of this estimate, maximum power point tracking (MPPT) can be realized.
*Efficiency of carrier separation and transportation;
*Enhanced charge separation occurs at interface between two materials with disparate electron affinities will transport in two materials and have low probability of recombination.
Paper demonstrated:
*5 nm PbSe nanocrystal: 5% external quantum efficiency (EQE, electrons/incident-photons per-second; internal QE: electrons/absorbed-photons per-second. 0.25% power conversion efficiency. Poor behavior due to poor transportation.
*Elongated particles have a tendency, that increases with size, to form *chains of particles connected along the c-axis
*4*7 nm PbSe nanocrystal after forming chain, can reach EQE as high as 4%
*8*13 nm PbSe nanocrystal after forming chain, can reach EQE as high as 16%
Larger size of PbSe nanocrystal are hard to fabricated, lead to question of what influence of nanocrystal’s shape has.


= Accurate measurements of solar irradiance for evaluation of photovoltaic power profiles =
== Authors ==
Filippo Spertino, Member, IEEE, Paolo Di Leo, Valeria Cocina
== Abstract ==
Based on five meteorological stations and the yearly experimental results, this paper discuss an observed phenomenon called ‘broken clouds’. This phenomena lead to noticeable peaks in measurement and PV power system. This effect occurs when clouds around sun amplified the beam irradiance, causing 20% more irradiance observed up to 500 W/m^2 lasting for minutes. It represent that investigation for this phenomena can be very useful to generate  desired peak power. This still need for further study.


= Development of Data Acquisition System for Hybrid Power Plant =
=== Charge transfer in photovoltaics consisting of interpenetrating networks of conjugated polymer and TiO2 nanoparticles <ref>[http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=4900326&abstractAccess=no&userType=inst A. C. Arango, S. A. Carter, and P. J. Brock, “Charge transfer in photovoltaics consisting of interpenetrating networks of conjugated polymer and TiO2 nanoparticles,” Applied Physics Letters, vol. 74, no. 12, pp. 1698–1700, Mar. 1999.]</ref>===
== Authors ==
[http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=4900326&abstractAccess=no&userType=inst A. C. Arango, S. A. Carter, and P. J. Brock, “Charge transfer in photovoltaics consisting of interpenetrating networks of conjugated polymer and TiO2 nanoparticles,” Applied Physics Letters, vol. 74, no. 12, pp. 1698–1700, Mar. 1999.]
Aryuanto Soetedjo, Yusuf Ismail Nakhoda
<br /><br />Use of interpenetrating donor-acceptor heterojunctions and interpenetrating polymer network can substantially improve the photoconductivity.
== Abstract ==
Layer fabrication: Opaque TiO2 layer is fabricated in thickness of 4-6 um, at particle size of 80 nm. Polymer is penetrated into TiO2 particle pores with size of 20 nm. Polymer is used as charge transporter.
Data acquisition system integrated wind speed monitor, Pyranometer and PV temperature measurement is realized. Low cost PV module is used as PV sensor. LABView is used as monitoring both wind speed and Pyranometer, and a SCADA  system used to control the system is introduced by L. Wang and K.H. Liu in ‘mplementation of a Web-Based Real-Time Monitoring and Control System for a Hybrid Wind-PV-Battery Renewable Energy System’. Pyranometer works at 10 V and 30mA. Low error down to 3.45% for solar irradiance measurement is realized. Work represent that high accuracy integrated measurement system to monitor both wind a solar irradiance can be achieved at a considerably cheap price.
ITO-(Layer)-Calcium sandwich.  
For current flow:
*Calcium acts like electron transfer;
*ITO acts like hole transfer. Hole should transfer from ITO to TiO2 valence band;
*Hole transfer from TiO2 valence band to ITO. However, insulation property of TiO2 prevent upper two situation from happening. But, under illumination, TiO2 presents property of accepting and conducting photo-excited electrons.  
Advantage: TiO2 has low conduction band, and has low saturation voltage (achieved by using stable and high-working function contact)


= A Neural Network-Based Low-Cost Solar Irradiance Sensor =
== Authors ==
Fernando Mancilla-David, Francesco Riganti-Fulginei, Antonino Laudani, Alessandro Salvini
== Abstract ==
Pyranometer is too expensive to be exploited in PV plants(?). To solve this, this paper introduced an approach to maximize efficiency based on neural networks. PV cell as irradiance sensor and a temperature senor and a low cost controller is used to realize this is introduced here to lower the cost. To use neural network (NN), a training set is introduced for learning, according to PV array mathematical model. After setting up the model, dataset was generated through experimental synthesis. System provide data for model to compute the irradiance. Compared to commercial Pyranometer(LM-10 HTD), this system provide a matched regression line, represents its high accuracy. However, paper did not give further discussion about the ignorance of peak irradiance due to algorithm.


= An Improved Model-Based Maximum Power Point Tracker for Photovoltaic Panels =
=== Quantum Dot Solar Cells. Tuning Photoresponse through Size and Shape Control of CdSe-TiO2 Architecture <ref>[http://pubs.acs.org/doi/abs/10.1021/ja0782706 A. Kongkanand, K. Tvrdy, K. Takechi, M. Kuno, and P. V. Kamat, “Quantum Dot Solar Cells. Tuning Photoresponse through Size and Shape Control of CdSe−TiO2 Architecture,” J. Am. Chem. Soc., vol. 130, no. 12, pp. 4007–4015, Mar. 2008.]</ref>===
== Authors ==
[http://pubs.acs.org/doi/abs/10.1021/ja0782706 A. Kongkanand, K. Tvrdy, K. Takechi, M. Kuno, and P. V. Kamat, “Quantum Dot Solar Cells. Tuning Photoresponse through Size and Shape Control of CdSe−TiO2 Architecture,” J. Am. Chem. Soc., vol. 130, no. 12, pp. 4007–4015, Mar. 2008.]
Loredana Cristaldi, Marco Faifer, Marco Rossi, and Sergio Toscani
<br /><br />
== Abstract ==
Basic principle for QD solar cells: Short-band-gap semiconductors such as CdS, PbS, Bi2S3, CdSe and InP can be used as sensitizers (to light?) due to their ability to transfer electrons to large-band-gap semiconductors such as TiO2 or SnO2 under visible light excitation. Short-band-gap also plays roll of extend TiO2 etc. to visible region.
A model-based maximum power point tracker is said to be able to offers a better dynamic performance than observation based MPPT system. It even did not require direct irradiance measurement. This paper built a circuit model. Meanwhile, it take generated thermal energy into account as uncoverted solar irradiance.
<br />Chemical and electrochemical deposited CdS and CdSe nanocrystal on TiO, SnO2 and ZnO surface can inject excited electrons and generate photocurrent under visible irradiation. But the efficiency is low due to fast charge recombination (where?) Refer to: [http://pubs.rsc.org/en/content/articlepdf/2011/cp/c0cp02605k The influence of dye structure on charge recombination in dye-sensitized solar cells] for details.
<br />TiO2 nanotubes scales: 80-90 nm in diameter and ~8 um in length. Hollow nature make tubes both inner and outer surface accessible for modification with sensitizing dyes or quantum dots. Tubes are upon Ti base, which is used as charge collector. Roughness factor: 48 for nanotubes and 75 for particles.
<br />Smaller-sized CdSe quantum dots show greater charge injection rates and also higher IPCE at the excitonic band. Larger particles have better absorption in the visible region but cannot inject electrons into TiO2 as effectively as smaller-sized CdSe quantum dots. 3.0 nm CdSe quantum dots were observed to be able to generate the highest photocurrent density @ 2 mA/cm^2 at response time between 20 sec and 45 sec.
<br />Incident Photo to Charge-carrier Efficiency (IPCE):
1240*short-circuit-photo-current@(A/cm^2) / (wavelength@nm*mono-incident-power@(W/cm^2))
<br />Through observation, smaller sized QD @2.3 nm is believed to give faster rate of electron transfer, may due to that they are more energetic in excited state to be capable of injecting (hot) electrons into TiO2 at faster rate.
<br />Absorption: TiO2 nanotube 5% higher than nanoparticle; IPCE: TiO2 nanotube 10% higher than nanoparticle.—Represent structure influence charge transfer.
<br />Electrons in TiO2 nanoparticles are more likely to loss at grain boundaries than those in TiO2 nanotubes.
<br />Observation of open circuit voltage shows that: with CdSe particles in nanotubes, electrons injected into nanotubes can survive longer thus to improve photocurrent generation efficiency of solar cells.
<br />Higher vacant energy levels of TiO2 facilitate direct electron transfer from the excited sensitizer in sub-psec time scale (what’s the ordinary time scale?)
<br />Rainbow solar cell: ordered assemblies of CdSe QDs of different diameters decorate TiO2 nanotubes.
*Downside: excess energy of electrons of small-sized particles is lost once they are transferred to TiO2.
*Advantage: faster electron injection rate and greater absorption range.
Future work: rainbow solar cell maximize light absorption of QD solar cell.


= A New Approach to Maximum Power Point Tracking for Photovoltaic Panels =
=== Dye-Sensitized solar cells<ref>[http://www.sciencedirect.com/science/article/pii/S1389556703000261 M. Grätzel, “Dye-sensitized solar cells,” Journal of Photochemistry and Photobiology C: Photochemistry Reviews, vol. 4, no. 2, pp. 145–153, Oct. 2003.]</ref> ===
== Authors ==
[http://www.sciencedirect.com/science/article/pii/S1389556703000261 M. Grätzel, “Dye-sensitized solar cells,” Journal of Photochemistry and Photobiology C: Photochemistry Reviews, vol. 4, no. 2, pp. 145–153, Oct. 2003.]
Loredana Cristaldi, Marco Faifer, Marco Rossi, Sergio Toscani
<br /><br />Light absorption and carrier transportation are separated in DSSC, light is absorbed by sensitizer, which has a range from UV to near IR. Solar to current efficiency (IPCE) @ AM 1.5 reaches 10% here.
== Abstract ==
<br />Structure:
MPPT( Maximum Power Point Tracker) system is designed and this paper shows a method that applied no direct measurement for solar irradiance for this system. This methods based on preset model, based on solar cell circuit model. According to measured circuit cell temperature, module voltage and current, the irradiance can be calculated. This system does not require radiometer that appeared in many model based MPPT systems. Its result shows a acceptable average error within 5%, although with several high error point as high as 25%.
*TiO2: mesoporous oxide layer, nano particles, where electronic transportation takes place. ZnO, Nb2O5 can also be used.
*Dye: where electrons are excited by photons and injected into conduction band of oxide.
*Electrolyte: provide electron donation to restore dye. Usually an organic solvent containing redox system.
Future study:
Dye should have these properties:
*Panchromatic
*Attachment group such as carboxylate or phosphonate.
*Upon excitation dye can inject electrons into oxide layer
*The energy level should match the lower bound of conduction band of oxide.
*Redox potential should be high enough to gain donation from electrolyte.
*Stable enough: 10^8 correspond 20 years of nature light
Organic dyes: coumarine or polyene solar-electric power conversion reaching up to 7.7% @ full sunlight
Problem for QD dye: photo-corrosion: unstable
<br />Mesoporou oxide film:
*Inherent conductivity is low
*Does not support built in E-field
*Three dimension transportation. Future study will focus on structure of higher degree of order.


= A Prototype of an Integrated Pyranometer for Measuring Multi-Parameters =
== Authors ==
Faiz Syazwan, Abdul Aziz1, Shahril Irwan Sulaiman, Hedzlin Zainuddin
== Abstract ==
System was design integrated with Pyranometer and temperature sensor module. Solar cell is used as sensor to build Pyranometer. Compare to commercial Pyranometer, this integrated solar censor can provide measurement with error between -6.01% and +2.92%.


= Simulation and energy management of an experimental solar system through adaptive neural networks =
== Authors ==
R.H. Fouad, M.S.Ashhab, A. Mukattash, S. Idwan
== Abstract ==
A solar system is built integrated a solar trainer that contains a photovoltaic panel, a DC centrifugal pump, flat plate collectors, storage tank, a flowmeter for measuring the water mass flow rate, pipes, pyranometer for measuring the solar intensity, thermocouples for measuring various system temperatures and wind speed meter. For Pyranometer, an artificial neural network is applied based on the difference between measured data and pre-learnt data. To increase accuracy, short term prediction is modeled according to Kaczmarz’s algorithm. Adaptation technique is introduced to improve the accuracy. ANN is used as a technique to compensate for system parts degradation, environmental variations, time changes and modeling errors. Result shows that adaptive ANN is more accurate than non-adaptive ANN system.


= Spectrally Selective Sensors for PV System Performance Monitoring =
=== The influence of dye structure on charge recombination in dye-sensitized solar cells <ref>[http://pubs.rsc.org/en/Content/ArticleLanding/2011/CP/c0cp02605k#!divAbstract J. R. Jennings, Y. Liu, Q. Wang, S. M. Zakeeruddin, and M. Grätzel, “The influence of dye structure on charge recombination in dye-sensitized solar cells,” Phys. Chem. Chem. Phys., vol. 13, no. 14, pp. 6637–6648, Apr. 2011.]</ref> ===
== Authors ==
[http://pubs.rsc.org/en/Content/ArticleLanding/2011/CP/c0cp02605k#!divAbstract J. R. Jennings, Y. Liu, Q. Wang, S. M. Zakeeruddin, and M. Grätzel, “The influence of dye structure on charge recombination in dye-sensitized solar cells,” Phys. Chem. Chem. Phys., vol. 13, no. 14, pp. 6637–6648, Apr. 2011.]
Anton Driesse, Daniela Dirnberger, Christian Reise, Nils Reich
<br /><br />Bipyridyl ruthenium failed to perform well in complete solar cells as sensitizer as expected. New sensitizer dyes with improved absorption of red part of solar spectrum should be developed.
== Abstract ==
<br />[http://www.sigmaaldrich.com/materials-science/organic-electronics/dye-solar-cells.html Z-907] has poorer PV performance when nonyl groups are replaced with amino groups due to higher rate of recombination (at surface or bulk?)
A spectrally matched reference solar cell is design to replace Pyranometer to measure plane of array(POA). System used two sensor with different non-overlapping spectral responses. Author used two sensors to measure the distribution of typical solar spectra. This method is proved to be useful for monitoring CdTe and CIS modules.


= Performance Testing using Silicon Devices – Analysis of Accuracy =
== Reference ==
== Authors ==
<references/>
Manajit Sengupta, Peter Gotseff, Daryl Myers, Thomas Stoffel1
<references/>
== Abstract ==
<references/>
This paper reviews the issues that will arise from the use of silicon detectors for PV performance measurement in the field based on measurements from a group of pyranometers mounted on a 1-axis solar tracker. Investigation is done on the impact of spectral sensitivity of silicon devices to find out why silicon based devices have more significant measurement difference. Experiment found that both Global Horizontal Irradiance(GHI) and Direct Normal Irradiance(DNI) measurements using silicon instruments have errors that are dependent on zenith angle. King et. al. (1998) correction have been devised to correct for these spectral errors.
<references/>
 
<references/>
= Online Photovoltaic Array Hot-spot Bayesian Diagnostics from Streaming String-Level Electric Data =
<references/>
== Authors ==
Shahar Ben-Menahem, Stephen C. Yang
== Abstract ==
Paper introduced prototype MAP-based, in-operation incipient hot-spot failure diagnostics and prognostics algorithm running on a central database server. This can be an effective and minimal-cost diagnostics solution. For a small 4-string array, the total hardware cost will amount to less than $100. This system can realize low-cost hot-spot fault detection, diagnostics and prediction in the same time.
 
= Power Rating Uncertainty Analysis of Electrical Performance of Photovoltaic Modules =
== Authors ==
Haitao Liu
== Abstract ==
Paper shows that more attention should be given to the reference devices such as reference cell, reference module or pyranometer which contribute majority of uncertainty components. Research based on uncertainty analysis for electrical performance parameters. Paper shows that this uncertainty analysis can be estimated for both flat plate PV modules and  concentrating PV modules or assemblies in practice.
 
= Miniature pyranometer with asteroid shape thermopile =
== Authors ==
Jiangang Zhang, Zhengwei Wu, Zhan Zhao, Xin Guan
== Abstract ==
A miniature pyranometer with a novel asteroid shape thermopile is designed with reduced size as small as 8mm by 4mm by 0.5mm. Output shows linear relation with irradiance. Resolution reached 0.191mV/10^5Lux. The thermopile unit is formed by sputtering technology, and the radiation absorption layer (Si3N4 film) is deposited above the thermopile layer by plasma-enhanced chemical vapor deposition. Silicon membrane is formed after the deposition.
 
= Design Of A Photovoltaic System For A Rural House =
== Authors ==
M.Aminy, N.Barhemmati, A.Hadadian, F.Vali
== Abstract ==
In this paper, calculation mean energy consumption of a rural area house, situating near Meshkin-dasht of Karaj providence in Iran is done. Using solar data registered in this area, the required electrical energy was calculated to be 2.88KWh with available mean solar radiation of 6 hours and rate of 6250MJ/m2. According to the calculations, 11 photovoltaic panels of 45W power and 2, 12V and 120Amph batteries as well as 2, 700W inverter are required. The rural house was considered for supplying AC electricity.
 
= PERFORMANCE ASSESSMENT WITHOUT PYRANOMETERS: PREDICTING ENERGY OUTPUT BASED ON HISTORICAL CORRELATION =
== Authors ==
Anastasios Golnas, Joseph Bryan, Robert Wimbrow, Clifford Hansen, and Steve Voss
== Abstract ==
An methodology is introduced. It can calculate the expected output of one or more systems in a regional fleet based on the measured power output from a subset of the total fleet. Method based on the correlation of historical data. With input information consisted of historical performance correlation and inter-system distance information, this method that can predict the energy output of a single PV system that belongs to a regional fleet by using information from other systems in that fleet. The best performing algorithm successfully predicted the weekly generation within 5% of the measured value between 73% and 96% of the time. When the accuracy threshold is relaxed to 10% the success rate varies between 91% and 99%. The monthly generation was predicted successfully at even higher rates – between 85% and 100% for a 5% threshold, and between 96% and 100% for a 10% threshold.
 
= Estimation of Photovoltaic Power Generation Output based on Solar Irradiation and Frequency Classification =
== Authors ==
P. Attaviriyanupap, K. Tokuhara, N. Itaya, M. Marmiroli, Y. Tsukamoto, Y. Kojima
== Abstract ==
In this paper, a method to estimate total power output of clustered photovoltaic power generation system (PV systems) is proposed. The proposed method make use of the real- time communication between pyranometer, current/voltage sensors, and control center to estimate power output of PV systems based on solar irradiation and power flow in the feeder, where PV systems are connected. The proposed method is divided into low-frequency and high-frequency component estimations. The low-frequency component is estimated based on the correlation between solar irradiation and energy generated from PV systems. On the other hand, the high-frequency component is estimated based on the frequency classification of power flow. The estimation is divided into low-frequency and high- frequency components estimation. The low-frequency component of PV power output is estimated based on the correlation between solar irradiation and energy generated from PV systems. The high-frequency component of PV power output is estimated based on the frequency classification of power flow in the feeder, where PV systems are connected.
Simulation results show that error is approximately 3-4% of installed capacity for offline and online estimation. Simulation results also show that the accuracy of the proposed method can be improved by including load model in the low-frequency component estimation process.
 
 
= Performance Improvement of SHWS by Increasing Thermal Efficiency Using Insulation Materials and Optimum Position of Solar Collectors =
== Authors ==
Jannatul Ferdous, Md Sanzidul Islam, Nabil Shaker, Bonny Amin Khan, A. Azad
== Abstract ==
Solar Hot Water System(SHWS) is designed. Pyranometers were placed on roof of a two storied building having fine surrounding aperture. Two channels of the same data acquisition card are used for Global Horizontal Irradiance (GHI) and Diffuse Irradiance (DIF) data. The solar radiation values are predicted using meteorological parameters as these parameters are related to nature. The monthly averaged daily diffuse radiation is calculated using Angstrom like correlation. The total radiation on the tilted surface plane is also estimated.
 
= Implementation of an intelligent sensor for measurement and prediction of solar radiation and atmospheric temperature =
== Authors ==
Joa ̃o M. Gomes∗,Pedro M. Ferreira†, Anto ́nio E. Ruano‡
== Abstract ==
An intelligent sensor is developed for acquiring temperature, solar radiation data and estimate cloudiness indexes, and use these measured values to predict temperature and solar radiation in a close future. This can be used in systems related to thermal comfort in buildings and to the efficient and intelligent use of solar energy. Pyranometer is introduced to regularly measure solar radiation. Neural networks of the type NARX, which use the acquired data to forecast the cloudiness index, solar radiation and temperature, in the next four hours period. The cloudiness estimation neural network was trained with images from the TSI, the difference of results were observed. This result influences the prediction of the radiation by NARX algorithm.
 
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Revision as of 23:09, 18 April 2014

This page is a literature review.Feel free to edit this page and add sources and summaries.Read more...
This is a literature page for project pyranometer in 2014 spring

Review

Quantum dot solar cells[1]

A. J. Nozik, “Quantum dot solar cells,” Physica E: Low-dimensional Systems and Nanostructures, vol. 14, no. 1–2, pp. 115–120, Apr. 2002.

Background: Hot carrier and impact ionization Hot carrier @ solar cells: Electrons/holes receives photons with energy much higher than their band gap will carry kinetic energy create effective temperature much higher than lattice temperature (3000K of carrier @ 300K of lattice etc.). Primary loss for this:

  • Heat through scattering (KN is transferred into band vibration?)
  • Photon emission (electrons occupied holes to let out photons?). Approach to stop this loss:
  • Stacked cascaded multiple p-n junctions to match multiple band of solar spectrum. This reduce carrier relaxation via photon emission. Efficiency increase to 66%.
  • Reduce thermal relaxation – utilize hot carriers before their relaxation.
    • Enhanced photo-voltage: being extracted before cooling; Requirement: transportation of hot carriers faster compare to the cool down rate – which should be related to the material itself.
    • Enhanced photo-current: create second or more electron-hoe pair(s) by impact ionization (Auger effect: one electron hit a band create one e-h pair. What will happen to this electron?); Requirement: impact ionization rate faster compare to the cool down rate & e-h pair transport rate faster than cool rate?.
    • Quantization confinement will dramatically reduce hot carrier’s cooling rates. (So this confinement will also reduce the cool down rate in Auger process which is not desired?)
  • What about some part of solar spectrum is absorbed to stimulate electron from En to En+1 or higher and the left spectrum will cause these electrons to emission from En+1 to En-1 to let out more photons with same lambda. Then one layer will be used to specifically to absorb these electrons.

Hot electrons and hot holes cool down rate are different because:

  • Mass difference (Which one is faster?)
  • Hot carrier cool rate depends on density of photo-generated hot carriers (How this makes diff?).

Predicted way for QDs: hot electrons with slowed cooling rate in QD --- Auger process, fast cool down hole due to mass & closer quantized space --- photo-currents. Bottleneck due to fast hole trap at the surface will slow cooling rate (7 ps at CdSe, InP QDs compare to 0.3 ps cooling rate without hole trap). This will prevent Auger process.
Suggested Syetems:

  • QD arrays in p-i-n cells. (Quasi-1D system)
    • Advantages:
      • Delocalized quantized 3-D miniband states might slow the carrier cooling rate to allow hot electron transportation and collection.
      • Impact ionization can occur, however not in the same time with hot electron transportation/collection.
    • Fabrication:
      • Colloidal
      • Epitaxial
    • Challenge:

Disorder of shape, surface state etc.

  • QD sensitized DSSC (Dye-sensitized solar cell)
    • Advantage:
      • Tunability of optical properties with size of QDs.
      • Quantum yield might be greater than 1, meaning one photon might generate more than one electron-hole pairs.
    • Fabrication:

Absorption from QD colloidal.

  • Quantum dots dispersed in organic semiconductor polymer matrices.

CdSe QDs are formed in hole conducting polymer. Structure of QDs affects the efficiency. Different layers can be applied to conduct electrons (TiO2) or holes (MEH-PPV). Challenge: electron-hole pair might recombine in surface of polymers. Refer to CdSe Nanocrystal Rods/Poly (3-hexylthiophene) Composite Photovoltaic Devices for rodlike CdSe QDs structure. Refer to Charge transfer in photovoltaics consisting of interpenetrating networks of conjugated polymer and TiO2 nanoparticles for multiple polymer structure.


CdSe Nanocrystal Rods/Poly (3-hexylthiophene) Composite Photovoltaic Devices[2]

W. U. Huynh, X. Peng, and A. P. Alivisatos, “CdSe Nanocrystal Rods/Poly(3-hexylthiophene) Composite Photovoltaic Devices,” Adv. Mater., vol. 11, no. 11, pp. 923–927, Aug. 1999.

Important factors affect the performance of a PV device includes:

  • Overlap of the absorption of solar spectrum;
  • Efficiency of carrier separation and transportation;
  • Enhanced charge separation occurs at interface between two materials with disparate electron affinities will transport in two materials and have low probability of recombination.

Paper demonstrated:

  • 5 nm PbSe nanocrystal: 5% external quantum efficiency (EQE, electrons/incident-photons per-second; internal QE: electrons/absorbed-photons per-second. 0.25% power conversion efficiency. Poor behavior due to poor transportation.
  • Elongated particles have a tendency, that increases with size, to form *chains of particles connected along the c-axis
  • 4*7 nm PbSe nanocrystal after forming chain, can reach EQE as high as 4%
  • 8*13 nm PbSe nanocrystal after forming chain, can reach EQE as high as 16%

Larger size of PbSe nanocrystal are hard to fabricated, lead to question of what influence of nanocrystal’s shape has.


Charge transfer in photovoltaics consisting of interpenetrating networks of conjugated polymer and TiO2 nanoparticles [3]

A. C. Arango, S. A. Carter, and P. J. Brock, “Charge transfer in photovoltaics consisting of interpenetrating networks of conjugated polymer and TiO2 nanoparticles,” Applied Physics Letters, vol. 74, no. 12, pp. 1698–1700, Mar. 1999.

Use of interpenetrating donor-acceptor heterojunctions and interpenetrating polymer network can substantially improve the photoconductivity. Layer fabrication: Opaque TiO2 layer is fabricated in thickness of 4-6 um, at particle size of 80 nm. Polymer is penetrated into TiO2 particle pores with size of 20 nm. Polymer is used as charge transporter. ITO-(Layer)-Calcium sandwich. For current flow:

  • Calcium acts like electron transfer;
  • ITO acts like hole transfer. Hole should transfer from ITO to TiO2 valence band;
  • Hole transfer from TiO2 valence band to ITO. However, insulation property of TiO2 prevent upper two situation from happening. But, under illumination, TiO2 presents property of accepting and conducting photo-excited electrons.

Advantage: TiO2 has low conduction band, and has low saturation voltage (achieved by using stable and high-working function contact)


Quantum Dot Solar Cells. Tuning Photoresponse through Size and Shape Control of CdSe-TiO2 Architecture [4]

A. Kongkanand, K. Tvrdy, K. Takechi, M. Kuno, and P. V. Kamat, “Quantum Dot Solar Cells. Tuning Photoresponse through Size and Shape Control of CdSe−TiO2 Architecture,” J. Am. Chem. Soc., vol. 130, no. 12, pp. 4007–4015, Mar. 2008.

Basic principle for QD solar cells: Short-band-gap semiconductors such as CdS, PbS, Bi2S3, CdSe and InP can be used as sensitizers (to light?) due to their ability to transfer electrons to large-band-gap semiconductors such as TiO2 or SnO2 under visible light excitation. Short-band-gap also plays roll of extend TiO2 etc. to visible region.
Chemical and electrochemical deposited CdS and CdSe nanocrystal on TiO, SnO2 and ZnO surface can inject excited electrons and generate photocurrent under visible irradiation. But the efficiency is low due to fast charge recombination (where?) Refer to: The influence of dye structure on charge recombination in dye-sensitized solar cells for details.
TiO2 nanotubes scales: 80-90 nm in diameter and ~8 um in length. Hollow nature make tubes both inner and outer surface accessible for modification with sensitizing dyes or quantum dots. Tubes are upon Ti base, which is used as charge collector. Roughness factor: 48 for nanotubes and 75 for particles.
Smaller-sized CdSe quantum dots show greater charge injection rates and also higher IPCE at the excitonic band. Larger particles have better absorption in the visible region but cannot inject electrons into TiO2 as effectively as smaller-sized CdSe quantum dots. 3.0 nm CdSe quantum dots were observed to be able to generate the highest photocurrent density @ 2 mA/cm^2 at response time between 20 sec and 45 sec.
Incident Photo to Charge-carrier Efficiency (IPCE): 1240*short-circuit-photo-current@(A/cm^2) / (wavelength@nm*mono-incident-power@(W/cm^2))
Through observation, smaller sized QD @2.3 nm is believed to give faster rate of electron transfer, may due to that they are more energetic in excited state to be capable of injecting (hot) electrons into TiO2 at faster rate.
Absorption: TiO2 nanotube 5% higher than nanoparticle; IPCE: TiO2 nanotube 10% higher than nanoparticle.—Represent structure influence charge transfer.
Electrons in TiO2 nanoparticles are more likely to loss at grain boundaries than those in TiO2 nanotubes.
Observation of open circuit voltage shows that: with CdSe particles in nanotubes, electrons injected into nanotubes can survive longer thus to improve photocurrent generation efficiency of solar cells.
Higher vacant energy levels of TiO2 facilitate direct electron transfer from the excited sensitizer in sub-psec time scale (what’s the ordinary time scale?)
Rainbow solar cell: ordered assemblies of CdSe QDs of different diameters decorate TiO2 nanotubes.

  • Downside: excess energy of electrons of small-sized particles is lost once they are transferred to TiO2.
  • Advantage: faster electron injection rate and greater absorption range.

Future work: rainbow solar cell maximize light absorption of QD solar cell.

Dye-Sensitized solar cells[5]

M. Grätzel, “Dye-sensitized solar cells,” Journal of Photochemistry and Photobiology C: Photochemistry Reviews, vol. 4, no. 2, pp. 145–153, Oct. 2003.

Light absorption and carrier transportation are separated in DSSC, light is absorbed by sensitizer, which has a range from UV to near IR. Solar to current efficiency (IPCE) @ AM 1.5 reaches 10% here.
Structure:

  • TiO2: mesoporous oxide layer, nano particles, where electronic transportation takes place. ZnO, Nb2O5 can also be used.
  • Dye: where electrons are excited by photons and injected into conduction band of oxide.
  • Electrolyte: provide electron donation to restore dye. Usually an organic solvent containing redox system.

Future study: Dye should have these properties:

  • Panchromatic
  • Attachment group such as carboxylate or phosphonate.
  • Upon excitation dye can inject electrons into oxide layer
  • The energy level should match the lower bound of conduction band of oxide.
  • Redox potential should be high enough to gain donation from electrolyte.
  • Stable enough: 10^8 correspond 20 years of nature light

Organic dyes: coumarine or polyene solar-electric power conversion reaching up to 7.7% @ full sunlight Problem for QD dye: photo-corrosion: unstable
Mesoporou oxide film:

  • Inherent conductivity is low
  • Does not support built in E-field
  • Three dimension transportation. Future study will focus on structure of higher degree of order.


The influence of dye structure on charge recombination in dye-sensitized solar cells [6]

J. R. Jennings, Y. Liu, Q. Wang, S. M. Zakeeruddin, and M. Grätzel, “The influence of dye structure on charge recombination in dye-sensitized solar cells,” Phys. Chem. Chem. Phys., vol. 13, no. 14, pp. 6637–6648, Apr. 2011.

Bipyridyl ruthenium failed to perform well in complete solar cells as sensitizer as expected. New sensitizer dyes with improved absorption of red part of solar spectrum should be developed.
Z-907 has poorer PV performance when nonyl groups are replaced with amino groups due to higher rate of recombination (at surface or bulk?)

Reference

  1. ↑ A. J. Nozik, “Quantum dot solar cells,” Physica E: Low-dimensional Systems and Nanostructures, vol. 14, no. 1–2, pp. 115–120, Apr. 2002.
  2. ↑ W. U. Huynh, X. Peng, and A. P. Alivisatos, “CdSe Nanocrystal Rods/Poly(3-hexylthiophene) Composite Photovoltaic Devices,” Adv. Mater., vol. 11, no. 11, pp. 923–927, Aug. 1999.
  3. ↑ A. C. Arango, S. A. Carter, and P. J. Brock, “Charge transfer in photovoltaics consisting of interpenetrating networks of conjugated polymer and TiO2 nanoparticles,” Applied Physics Letters, vol. 74, no. 12, pp. 1698–1700, Mar. 1999.
  4. ↑ A. Kongkanand, K. Tvrdy, K. Takechi, M. Kuno, and P. V. Kamat, “Quantum Dot Solar Cells. Tuning Photoresponse through Size and Shape Control of CdSe−TiO2 Architecture,” J. Am. Chem. Soc., vol. 130, no. 12, pp. 4007–4015, Mar. 2008.
  5. ↑ M. Grätzel, “Dye-sensitized solar cells,” Journal of Photochemistry and Photobiology C: Photochemistry Reviews, vol. 4, no. 2, pp. 145–153, Oct. 2003.
  6. ↑ J. R. Jennings, Y. Liu, Q. Wang, S. M. Zakeeruddin, and M. Grätzel, “The influence of dye structure on charge recombination in dye-sensitized solar cells,” Phys. Chem. Chem. Phys., vol. 13, no. 14, pp. 6637–6648, Apr. 2011.



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