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Open-pv.png This page is part of an MTU graduate course MY5490/EE5490: Solar Photovoltaic Science and Engineering. Both the course documentation and the course generated content is open source. However, the course runs over Spring semesters during this time it is not open edit. Please leave comments using the discussion tab.


1."Photovoltaics — a path to sustainable futures"

By Joshua M Pearce

Review:As both population and energy use per capita increase, modern society is approaching physical limits to its continued fossil fuel consumption. The immediate limits are set by the planet’s ability to adapt to a changing atmospheric chemical composition, not the availability of resources. In order for a future society to be sustainable while operating at or above our current standard of living a shift away from carbon based energy sources must occur. An overview of the current state of active solar (photovoltaic, PV) energy technology is provided here to outline a partial solution for the environmental problems caused by accelerating global energy expenditure. The technical, social, and economic benefits and limitations of PV technologies to provide electricity in both off-grid and on-grid applications is critically analyzed in the context of this shift in energy sources. It is shown that PV electrical production is a technologically feasible, economically viable, environmentally benign, sustainable, and socially equitable solution to society’s future energy requirements.

2."Multiple-input Maximum Power Point Tracking algorithm for solar panels with reduced sensing circuitry for portable applications "

By F. Boico, B. Lehman

Review:A method to track the maximum power of multiple-input, portable, photovoltaic systems is proposed. The method shares a single current sensor by interleaving Perturb and Observe operations. The system has reduced size and cost, making it attractive for compact portable solar panels and solar battery chargers, such as for cell phones, laptops, and other portable electronics with rechargeable batteries. A flexible total system architecture design is proposed and tested.

3."Tree canopy shade impacts on solar irradiance received by building walls and their surface temperature "

By Rowan Berry a, Stephen J. Livesley, Lu Ayeb

Review:Shading coefficients are used to predict the seasonal and diurnal benefit of architectural shading devices. It is more difficult to model the impact of tree shade on building thermal performance, and data is rare and varies greatly with species and season. We established a range of tree shade amounts and shade qualities from which to develop simple, robust models that predict external wall surface temperatures. We measured percentage shade cover, solar irradiance and external surface temperature on north and west sun-bearing walls of three identical buildings in spring and summer 2010/11. One building was shaded by tall Angophora trees, another by smaller Fraxinus trees and one was unshaded. Tree shade reduced wall surface temperatures by up to 9 C and external air temperatures by up to 1 C. The smaller trees did little to reduce external wall surface temperatures, and moving the tall trees further away from the building wall eliminated their cooling benefits. Wall surface temperatures were best predicted by shade cover and solar irradiance, and was most poorly predicted by shading coefficients, that varied greatly through the day and the season, as tree height and leaf area index increased. Trees can reduce external solar irradiance loads when they are close enough and tall enough to shade the majority of the wall. To simulate the thermal performance benefits that trees provide, it is necessary to account for seasonal, growth and phenological changes in tree shade amount and quality.

4."Design of DSC panel with efficiency more than 6%"

By Songyuan Dai, Kongjia Wang, Jian Weng, Yifeng Sui, Yang Huang, Shangfeng Xiao, Shuanghong Chen, Linhua Hu, Fantai Kong, Xu Pan, Chengwu Shi, Li Guo

Review:Dye sensitized solar cells (DSCs), as a new innovative technology, were developed very quickly in the past decade since Prof. M. Gra¨ tzel (EPFL) made the breakthrough in 1991 (Nature 353 (1991) 737). While photoelectric conversion efficiency of 11.04% was achieved last year in EPFL (J. Photocem. Photobiol. A: Chem. 164 (2004) 3), 8.2% was achieved with a size of 2.36 cm2 in 2001 by the ECN group (Sol. Energy Mater. Sol. Cells 84 (2004) 125), which is a very exciting result for large scale DSCs. As potential low cost solar cells, DSC module and the panel’s efficiency and stability are still critical problems to the way of marketing. We show our research in the test and design of modules and panels in the past few years at our institute. We have achieved photoelectric conversion efficiency around 6% with 15X20 cm2 module, and our future primary 500W DSC power station with the same performance 40X60 cm2 panel is under way.

5."Maximum power point tracking without current sensor for photovoltaic module integrated converter using Zigbee wireless network "

By Sol Moon, Seong-Jin Kim, Jeong-Won Seo, Joung-Hu Park ⇑, Changkun Park, Chan-Su Chung

Review:In this paper, a simple maximum power point tracking method for series-connected DC–DC converter module of photovoltaic power conditioning systems is proposed. This approach enables maximum power point tracking control with the converter’s output voltage information instead of calculating solar array power, which significantly simplifies the sensor network by removing any current sensor. Furthermore, there is no multiplication process of power calculation for perturbation-and-observation algorithm to track the maximum power point because the power calculation is replaced by simple output voltage sensing. This simple tracker realization can reduce the cost and size, and can be utilized with a low performance/ low cost controller. For the implementation of the proposed control strategy, Zigbee (Xbee-pro) wireless communications and DSP’s Series Communications Interface are utilized. Then, a couple of series- connected hardware prototype of photovoltaic modules was built and tested for the performance evaluation.

6."Titania solar cells: new photovoltaic technology "

By George Phani*, Gavin Tulloch, David Vittorio, Igor Skryabin

Review:Titania solar cells are a new type of photovoltaic device invented by Professor Michael GraÈ tzel at Ecole Polytechnique Federale de Lausanne (Switzerland). Titania solar cells convert sunlight directly into electricity through a process similar to photosynthesis. It has performance advantages over other solar cells, which include the ability to perform well in low light and shade, and to perform consistently well over a wide range of temperatures. Titania solar cells can be fabricated to be either transparent or opaque in appearance. The simple materials, construction technique and processing equipment make Titania modules attractive for a€ordable power generation. Applications of such a module include many consumer and professional products, including vertically mounted solar tiles used as integrated building materials and, in future, used as power generating windows. 7 2000

7."Concepts of inorganic solid-state nanostructured solar cells "

By Thomas Dittrich n, AbdelhakBelaidi 1, AhmedEnnaoui

Review:The development of inorganic solid-state nanostructured solar cells over the last years has been reviewed with respect to concepts and materials. Major attention has been paid to solar cells with extremely thin absorber, solar cells with ultra-thin nano-composite absorber and solar cells with quantum dot absorber layers. The focus has been set to structured transparent electron conductors and absorber materials prepared by mainly low-temperature and wet chemical deposition methods. The great potential of inorganic solid-state nanostructured solar cells is discussed.

8."Photovoltaic electrochromic device for solar cell module and self-powered smart glass applications "

By Lee-May Huang a,n, Chih-WeiHub, Han-ChangLiu a, Chih-YuHsu c, Chun-HengChen a, Kuo-ChuanHo

Review:An innovative concept of solution type photovoltaic electrochromic (PV-EC) device has been developed. The device includes a semi-transparent silicon thin-film solar cell (Si-TFSC) substrate, an electro- chromic solution, and a transparent non-conductive substrate, wherein the electrochromic solution is located between the transparent non-conductive substrate and the Si-TFSC substrate. The solution type PV-EC device has at least the following advantages: (1) the electrodes in the PV-EC device are planarly distributed in the whole semi-transparent Si-TFSC substrate to create a uniform electric field, which makes large area PV-EC module application feasible; (2) since the PV-EC device can be driven with low voltage and low current, the demand for photopotential and photocurrent produced by the Si-TFSCs is lowered and thus the thickness of an intrinsic layer in each of the Si-TFSCs can be thinned, which increases the transmittance of the device, and (3) the electrical power generated by the PV-EC module can be controlled by an additional output switch layout coupled with the Si-TFSC. When illuminated by sunlight, a portion of electronic current produced by a Si-TFSC is converted into ionic current to cause color changing of the PV-EC device, while the monolithically integrated Si-TFSC module generates electricity to a connected load. In view of photoelectric conversion and optical modulation properties, the PV-EC device can both function as solar cell module and as self-powered smart glass, which has great advantages in green energy application.

9."Design and fabrication of diffusive solar cell window "

By Ruei-Tang Chen, Joseph Lik Hang Chau*, Gan-Lin Hwang

Review:A diffusive solar cell window was designed and fabricated with uniformly distributed nanocomposite particles in a light diffusive plate that was sandwiched between two glass layers. The entire composite construction transfers light radiation to solar cells at the edge of the windows. It is based on a new combination of existing technologies because of it uses mature, mass-produced components - solar cells - as well as nanocomposite particles that are embedded inside the light-guide plate. They are integrated using an inexpensive and widely used method for making building windows. The result is an inexpensive, strong, stable, viewquality-preserving solar energy-harvesting windowthat has no close competition. The diffusive solar cell window does not suffer from aging, and products that are made using diffusive solar cell window technology will be new entries to the solar power generation window market.

10."Modeling and maximum power point tracking (MPPT) method for PV array under partial shade conditions "

By Jun Qi, Youbing Zhang, Yi Chen

Review:Influenced by partial shade, PV module aging or fault, there are multiple peaks on PV array’s output powerevoltage (PeV) characteristic curve. Conventional maximum power point tracking (MPPT) methods are effective for single peak PeV characteristic under uniform solar irradiation, but they may fail in global MPP tracking under multi-peak PeV characteristics. Existing methods in literature for this problem are still unsatisfactory in terms of effectiveness, complexity and speed. In this paper, we first analyze the mathematical model of PV array that is suitable for simulation of complex partial shade situation. Then an adaptive MPPT (AMPPT) method is proposed, which can find real global maximum power point (MPP) for different partial shade conditions. When output characteristic of PV array varies, AMPPT will adjust tracking strategies to search for global peak area (GPA). Then it is easy for conventional MPPT to track the global MPP in GPA. Simulation and experimental results verify that the proposed AMPPT method is able to find real global MPP accurately, quickly and smoothly for complex multi-peak P eV characteristics. Comparison analysis results demonstrate that AMPPT is more effective for most shade types.

11."Light and energy—dye solar cells for the 21st century "

By Gavin E. Tulloch

Review:Dye solar cells (DSC) are the first commercially available third generation solar cell technology. DSC have been subject of increasing laboratory research since first reported by Grätzel in 1991 [Nature 353 (1991) 737]. Much of that work has been involved with laboratory scale cells of less than 1 cm2. The knowledge resources required to undertake research in DSC are much broader than those necessary for traditional solar cell technologies such as silicon. These elements are discussed and related to the operation of the DSC, from which the relative advantages of DSC are gleaned. The experience gained from laboratory work has formed the basis for market expectations concerning performance and stability of DSC in commercial applications. However, it has been found that there is a new set of variables to be addressed when taking the technology from the laboratory cell level to the module and product level. This paper describes the background cell technology and the module designs considered for the first production DSC modules and explains the reasons for selection of the preferred design for outdoor applications. A number of alternative product designs that are expected to be commercially viable in the next several years are discussed. In conclusion some tandem designs demonstrate the potential of DSC for integrated products to serve the energy market.

12."100 mm × 100 mm large-sized dye sensitized solar cells "

By Kenichi Okada, Hiroshi Matsui, Takuya Kawashima, Tetsuya Ezure, Nobuo Tanabe

Review:In this study, up sizing technology of dye sensitized solar cells (DSC) was developed. Conversion efficiency of large cells was drastically decreased if it was fabricated by ordinary materials and processes of mini size cells, due to its high internal resistance. We investigated a method to reduce sheet resistant of transparent conductive substrates. It was found that nickel was appropriate for current correcting lines of DSCs because of its lifetime in a redox electrolyte, and low dark current density to the electrolyte. High conductive transparent substrates were fabricated with nickel grids formed by an electroplating process and fluorine doped SnO2/ITO double layered transparent conductive oxides. These substrates achieved low sheet resistance 0.28 and 66% light transmittance, and 4.3% conversion efficiency in the total area, 5.1% in the active area was obtained on a 100mm × 100mm size large cell.

13."A current and future study on non-isolated DC–DC converters for photovoltaic applications "

By M.H. Taghvaee a,n, M.A.M.Radzi a, S.M.Moosavain b, HashimHizam a, M.HamiruceMarhaban

Review:Photovoltaic (PV) is a fast growing segment among renewable energy (RE) systems, whose develop- ment is owed to depleting fossil fuel and climate-changing environmental pollution. PV power output capacity, however, is still low and the associated costs still high, so efforts continue to develop PV converter and its controller, aiming for higher power-extracting efficiency and cost effectiveness. Different algorithms have been proposed for Maximum Power Point Tracking (MPPT). Since the choice of right converter for different application has an important influence in the optimum performance of the photovoltaic system, this paper reviews the state-of-the-art in research works on non-isolated DC–DC buck, boost, buck–boost, Cu´ k and SEPIC converters and their characteristics, to find a solution best suiting an application with Maximum Power Point Tracking. Review shows that there is a limitation in the system’s performance according to the type of converter used. In can be concluded that the best selection of DC–DC converter which is really suitable and applicable in the PV system is the buck–boost DC–DC converter since it is capable of achieving optimal operation regardless of the load value with negotiable performance efficiency and price issue

14."A review of solar photovoltaic technologies "

By Bhubaneswari Paridaa, S. Iniyanb, Ranko Goicc

Review:Global environmental concerns and the escalating demand for energy, coupled with steady progress in renewable energy technologies, are opening up new opportunities for utilization of renewable energy resources. Solar energy is the most abundant, inexhaustible and clean of all the renewable energy resources till date. The power from sun intercepted by the earth is about 1.8×1011 MW, which is many times larger than the present rate of all the energy consumption. Photovoltaic technology is one of the finest ways to harness the solar power. This paper reviews the photovoltaic technology, its power generating capability, the different existing light absorbing materials used, its environmental aspect coupled with a variety of its applications. The different existing performance and reliability evaluation models, sizing and control, grid connection and distribution have also been discussed.

15."Third generation photovoltaics: solar cells for 2020 and beyond "

By Martin A. Green∗

Review:Many workingin the )eld of photovoltaics believe that ‘)rst generation’ silicon wafer-based solar cells sooner or later will be replaced by a ‘second generation’ of lower cost thin-)lm technology, probably also involving a di.erent semiconductor. Historically, CdS, a-Si, CuInSe2, CdTe and, more recently, thin-)lm Si have been regarded as key thin-)lm candidates. Since any mature solar cell technology is likely to evolve to the stage where costs are dominated by those of the constituent materials, be it silicon wafers or glass sheet, it is argued that photovoltaics will evolve, in its most mature form, to a ‘third generation’ of high-e4ciency thin-)lm technology. By high e4ciency, what is meant is energy conversion values double or triple the 15–20% range presently targeted. Tandem cells provide the best-known example of such high-e4ciency approaches, where e4ciency can be increased merely by adding more cells of di.erent band gap to a stack. However, a range of other better-integrated approaches are possible that o.er similar e4ciency to an in)nite stack of such tandem cells.


By Bemard L. Sater and Neil D. Sater

Review:High voltage silicon vertical multi-junction (VMJ) solar cells are ideally suited for providing efficient operation at solar intensities exceeding 1000 suns AM1.5. This paper discusses the unique features and advantages of the VMJ cell. The authors believe the high output power performance capability and manufacturing simplicity of VMJ cells will enable more cost-effective photovoltaic concentrator system designs. Preliminary test data is shown for a 0.78 cm2 VMJ cell with 40 series connected junctions producing 31.8 watts at 25.5 volts at near 2500 suns AM1.5 intensity (40.4 watts per cmz output at 211 watts per cmz input with an estimated efficiency near 20%)

17."Photovoltaic Module Shading: Smart Grid Impacts "

By Peter Mark Jansson, Senior Member, Kevin Whitten, Member, John L. Schmalzel, Fellow

Review:In the design of a solar photovoltaic system, one criterion that continues to receive low priority is the provision of minimum inter row spacing for photovoltaic modules. Consumers and installers alike strive to maximize area usage for systems such that they achieve the highest amount of annual energy output. This, in turn, leads to module rows being designed very close to each other; with array tilt lowered in an attempt to reduce inter row shading. This design practice fails to take into consideration many effects that close row spacing can have on system output. When designing a photovoltaic array to optimize its performance as a power generator and its contribution to the electric grid during peak demand periods – shading concerns become a key consideration. This paper describes a process developed at Rowan University’s Center for Sustainable Design to test the impact that inter row shading can have on power output and performance across the day. A test rig and protocol were created which tested module’s output given various depths of shading from one row of modules upon another. The exclusion of bypass diodes in the system was also tested to view the most extreme possible cases of power loss induced by shading. The results of this experimentation showed that even very small amounts of shading upon solar photovoltaic modules can lead to significant loss in power generation. As more PV systems are installed on the utility system their availability during peak times becomes an ever increasing requirement for Smart Grid success. This paper also explores the ramifications that proper inter row spacing design guidelines could have on reinforcing some of the fundamental principles of Smart Grid.

18."Improved Energy Capture in Series String Photovoltaics via Smart Distributed Power Electronics "

By Leonor Linares, Student Member, IEEE, Robert W. Erickson, Fellow, IEEE, Sara MacAlpine, and Michael Brandemuehl

Review:This paper proposes an improved module integrated converter to increase energy capture in the photovoltaic (PV) series string. Prototypes for self-powered, high efficiency dc-dc converters that operate with autonomous control for tracking the maximum power of solar panels locally and on a fine scale are simulated, built and tested. The resulting module is a low-cost, reliable smart PV panel that operates independently of the geometry and complexity of the surrounding system. The controller maximizes energy capture by selection of one of three possible modes: buck, boost and pass-through. Autonomous controllers achieve noninteracting maximum power point tracking and a constant string voltage. The proposed module-integrated converters are verified in simulation. Experimental results show that the converter prototype achieves efficiencies of over 95% for most of its operating range. A 3-module PV series string was tested under mismatched solar irradiation conditions and increases of up to 38% power capture were measured.

19."Application of Adaptive Algorithm of Solar cell battery charger "

By Cong-Ling Hou, Jie Wu, Miao Zhang , Jin-Ming Yang and Jin-Peng Li

Review:This paper presents the adaptive algorithm to resolve the problem in the maximum power point tracking (MPPT) of solar cell battery charger and applies it in the design for MPPT system. Results of the research show that the adaptive algorithm has not only accelerated the calculating speed and strengthen the searching performances, but also has the high tracking precision.

20."A Study of the Remaining Battery Power Indication Circuit for Independent Solar Cell Control Systems "

By S. Usudal, T. Sunagawal, K. Miyoshi2 and J. Lei3 IIndustrial Systems Engineering, Osaka Prefectural College of Technology, Osaka, Japan 2Tsukasa Electric Industry Co.,Ltd, Osaka, Japan

Review:An independent solar cell control system operates without supply from an external commercial power source. The system usually consists of solar cells, a storage battery, a DC load and a control circuit. For systems of this kind, it is very important to equip them with a recharge and discharge function that can work efficiently in all seasons and a function with which to tell the battery operation status. This paper is to report on our study of battery recharge and discharge characteristics for designing a circuit that indicates remaining power in the solar-cell battery. The study also includes the developing of a method to design the said circuit, as well as primary performance and field tests on a trial product of the circuit we designed using that method.

21."Solar Cell as a Capacitive Temperature Sensor "

By H. ANANTHA KRISHNA N. K. MISRA ISRO Satellite Centre M. S. SURESH BNM Institute of Technology

Review:Spacecrafts in geostationary Earth orbit and low Earth polar orbit experience temperatures in the range of ¡180±C to 80±C [1, 2] depending on the orbit. Solar cells are mounted on light weight aluminum honeycomb panels which are deployed and Sun pointed in on-orbit operation. Solar panels charge batteries and supply power to the satellite during sunlit period and batteries supply power during eclipse period. The open circuit voltage (Voc) of a silicon solar cell varies by about ¡2:5 mV=±C [3] and temperature can bring about a dramatic change in the solar cell characteristic, particularly with reference to operating voltage. PRT mounted on the rare of the solar panel measure the temperature of the solar panel. This introduces errors due to temperature gradients between solar cell blanket and solar panel and slow transient response of PRTs. A method of using solar cell capacitance to measure the temperature of solar cell blanket is proposed. This removes error due to location and transient response of PRT. Solar cell as a temperature sensor for measurement of temperature is demonstrated.

22."Status of thin film solar cells in research, production and the market "

By Arnulf Ja¨ger-Waldau

Review:Photovoltaics is one of the fastest growing industries at present. Over the last five years, the production of photovoltaic solar cells has steadily increased at an annual average of 40%, driven not only by the progress in materials and processing technology, but by market introduction programmes in many countries around the world. This growth is mainly being attained by an increase in manufacturing capacities based on the technology of crystalline, single junction devices. Consistent with the time needed for any major change in energy infrastructure, another 20–30 years of sustained and aggressive growth will be required for photovoltaics to substitute a significant share of conventional energy sources. The question is whether a switch will be possible with the current technologies alone or whether this growth will only be possible with the continuous introduction of new technologies. It leads us to the search for new developments with respect to material use and consumption, device design and production technologies as well as new concepts to increase overall efficiency. This paper analyses the current status of thin film solar cells and their outlook for future developments.

23."Hybrid Micropower Source for Wireless Sensor Network"

By Yanqiu Li, Hongyun Yu, Bo Su, and Yonghong Shang

Review:Wireless sensor networks have become a very significant enabling technology in many applications and the use of environmental energy is a feasible source for low-power wireless sensor networks. The challenges of developing a power supply including generation or conversion, storage, and power management are manifold to extend the lifetime of a wireless sensor network. The objective of this research is to develop an intelligent hybrid power system to realize a self-sustaining wireless sensor node. The photovoltaic and thermoelectric generators are adopted as energy converters. The lithium ion battery and ultracapacitor are used as reservoirs. An intelligent power management system has been developed to control the power distribution. The design data and experimental results show that the hybrid micropower source can extend the lifetime of a sensor network.

24."Battery Management System for Solar Energy Applications "

By Glavin, M. ; Nat. Univ. of Ireland, Galway ; Hurley, W.G.

Review:Generally in photovoltaic applications the storage battery has the highest life time cost in the system; it has a profound affect on the reliability and performance of the system. Currently the most commonly used storage technology for photovoltaic applications is the lead acid battery. The advantages of the lead acid battery are its low cost and great availability. The problem is that photovoltaic panels are not an ideal source for charging batteries. With the lead acid battery the charging regime may have a significant impact on its service life. The battery management system described in this paper aims to optimize the use of the battery, to prolong the life of the battery, making the overall system more reliable and cost effective. Maximum power point tracking will also be incorporated into the battery management system, to move the solar array operating voltage close to the maximum power point under varying atmospheric conditions, in order to draw the maximum power from the array. This paper will describe different battery technologies that are currently used with photovoltaic systems along with some of the charging techniques that are available

25."Design of a Solar-Harvesting Circuit for Batteryless Embedded Systems "

By Brunelli, D. ; Dept. of Electron., Comput. Sci. & Syst. (DEIS), Univ. of Bologna, Bologna, Italy ; Moser, C. ; Thiele, L. ; Benini, L

Review:The limited battery lifetime of modern embedded systems and mobile devices necessitates frequent battery recharging or replacement. Solar energy and small-size photovoltaic (PV) systems are attractive solutions to increase the autonomy of embedded and personal devices attempting to achieve perpetual operation. We present a battery less solar-harvesting circuit that is tailored to the needs of low-power applications. The harvester performs maximum-power-point tracking of solar energy collection under nonstationary light conditions, with high efficiency and low energy cost exploiting miniaturized PV modules. We characterize the performance of the circuit by means of simulation and extensive testing under various charging and discharging conditions. Much attention has been given to identify the power losses of the different circuit components. Results show that our system can achieve low power consumption with increased efficiency and cheap implementation. We discuss how the scavenger improves upon state-of-the-art technology with a measured power consumption of less than 1 mW. We obtain increments of global efficiency up to 80%, diverging from ideality by less than 10%. Moreover, we analyze the behavior of super capacitors. We find that the voltage across the supercapacitor may be an unreliable indicator for the stored energy under some circumstances, and this should be taken into account when energy management policies are used.

26."A stand-alone photovoltaic supercapacitor battery hybrid energy storage system"

By Glavin, M.E. ; Power Electron. Res. Centre, Nat. Univ. of Ireland, Galway ; Chan, P.K.W. ; Armstrong, S. ; Hurley, W.G.

Review:Most of the stand-alone photovoltaic (PV) systems require an energy storage buffer to supply continuous energy to the load when there is inadequate solar irradiation. Typically, Valve Regulated Lead Acid (VRLA) batteries are utilized for this application. However, supplying a large burst of current, such as motor startup, from the battery degrades battery plates, resulting in destruction of the battery. An alterative way of supplying large bursts of current is to combine VRLA batteries and supercapacitors to form a hybrid storage system, where the battery can supply continuous energy and the supercapacitor can supply the instant power to the load. In this paper, the role of the supercapacitor in a PV energy control unit (ECU) is investigated by using Matlab/Simulink models. The ECU monitors and optimizes the power flow from the PV to the battery-supercapacitor hybrid and the load. Three different load conditions are studied, including a peak current load, pulsating current load and a constant current load. The simulation results show that the hybrid storage system can achieve higher specific power than the battery storage system.

27."Photovoltaics — Control of hybrid battery/ultra-capacitor energy storage for stand-alone photovoltaic system"

By Xiong Liu ; Div. of Power Eng., Nanyang Technol. Univ., Singapore, Singapore ; Peng Wang ; Poh Chiang Loh ; Feng Gao

Review:Battery life is an important criterion in a stand-alone photovoltaic system operation due to intermittent characteristic of solar irradiation and demand. This paper presents a stand-alone photovoltaic system with Ni-MH battery and ultra-capacitor serving as its energy storage elements. A control strategy is proposed in this paper to reduce charging and discharging cycles and avoid deep discharges of battery. The battery converter is controlled in current mode to track a charging/discharging reference current which is given by energy management system, whereas the ultra-capacitor converter is controlled to corporate solar irradiation fluctuations, load spikes and variations to maintain a stable dc-link voltage. Isolated PV system with the proposed control schemes is created using MATLAB SIMULINK. An optimum performance is achieved to serve as both high power and high energy sources due to complementary characteristic of battery and ultra-capacitor.

28."Combined low-cost, high-efficient inverter, peak power tracker and regulator for PV applications "

By Enslin, J.H.R. ; Dept. of Electr. Eng., Pretoria Univ., South Africa ; Snyman, D.B.

Review:A novel compound power converter that serves as a DC-to-AC inverter, maximum power point tracker (MPPT), and battery charger for stand-alone photovoltaic (PV) power systems is introduced. A theoretical analysis of the proposed converter is performed, and the results are compared with experimental results obtained from a 1.5 kW prototype. The overall cost of PV systems can thus be reduced by using load management control and efficiency-optimization techniques. Power flow through the converter is controlled by means of a combination of duty cycle and output frequency control. With load management, large domestic loads, such as single phase induction motors for water pumping, hold-over refrigerators, and freezers, can be driven by day at a much higher energy efficiency. This is due to the high efficiency of the inverter with high insolation, and because the inverter uses the energy directly from the solar array. The battery loss component is thus reduced

29."Matching of a DC motor to a photovoltaic generator using a step-up converter with a current-locked loop "

By Alghuwainem, S.M. ; Dept. of Electr. Eng., King Saud Univ., Riyadh, Saudi Arabia

Review:A photovoltaic (PV) generator is a nonlinear device having insolation-dependent volt-ampere characteristics. Because of its relatively high cost, the system designer is interested in optimum matching of the motor and its mechanical load to the PV generator so that maximum power is obtained during the entire operating period. However, since the maximum-power point varies with solar insolation, it is difficult to achieve an optimum matching that is valid for all insolation levels. In this paper it is shown that for maximum power, the generator current must be directly proportional to insolation. This remarkable property is utilized to achieve insolation-independent optimum matching. A shunt DC motor driving a centrifugal water pump is supplied from a PV generator via a step-up converter whose duty ratio is controlled using a current-locked feedback loop

30."A Simple Single-Sensor MPPT Solution "

By Pandey, A. ; Rocsys Technol., Hyderabad ; Dasgupta, N. ; Mukerjee, A.K.

Review:Maximum power point trackers (MPPTs) are used to ensure optimal utilization of solar cells. The implementation essentially involves sensing input current and voltage. An MPPT algorithm uses this information to maximize power drawn from the solar cells. Understandably, such realization is costly. Current state of the art allows replacing one of the sensors by complicated computations. In the present work, an empirical observation is used to develop a strategy, which employs a single voltage sensor and carries out simple computations for a buck converter-based MPPT

31."Maximum power point tracking: a cost saving necessity in solar energy systems "

By Enslin, J.H.R. ; Dept. of Electr. Eng., Pretoria Univ., South Africa

Review:It is argued that a well-engineered renewable remote energy system utilizing the principal of maximum power point tracking (MPPT) can be cost effective, has a high reliability, and can improve the quality of life in remote areas. A highly efficient power electronic converter for converting the output voltage of a solar panel or wind generator to the required DC battery bus voltage has been realized. The converter is controlled to track the maximum power point of the nput source under varying input and output parameters. MPPT for relatively small systems is achieved by maximization of the output current in a battery charging regulator, using an optimized hill-climbing, inexpensive microprocessor-based algorithm. Through field measurements it is shown that a minimum input source saving of 15% on 3-5 kWh/day systems can easily be achieved

32."Comparison of Photovoltaic Array Maximum Power Point Tracking Techniques "

By Esram, T. ; Illinois Univ., Urbana, IL ; Chapman, P.L.

Review:The many different techniques for maximum power point tracking of photovoltaic (PV) arrays are discussed. The techniques are taken from the literature dating back to the earliest methods. It is shown that at least 19 distinct methods have been introduced in the literature, with many variations on implementation. This paper should serve as a convenient reference for future work in PV power generation.

33."Integrated photovoltaic maximum power point tracking converter "

By Enslin, J.H.R. ; Dept. of Electr. & Electron. Eng., Stellenbosch Univ., South Africa ; Wolf, M.S. ; Snyman, D.B. ; Swiegers, W.

Review:A low-power low-cost highly efficient maximum power point tracker (MPPT) to be integrated into a photovoltaic (PV) panel is proposed. This can result in a 25% energy enhancement compared to a standard photovoltaic panel, while performing functions like battery voltage regulation and matching of the PV array with the load. Instead of using an externally connected MPPT, it is proposed to use an integrated MPPT converter as part of the PV panel. It is proposed that this integrated MPPT uses a simple controller in order to be cost effective. Furthermore, the power converter has to be very efficient, in order to transfer more energy to the load than a directly-coupled system. This is achieved by using a simple soft-switched topology. A much higher conversion efficiency at lower cost will then result, making the MPPT an affordable solution for small PV energy systems

34."A fuzzy logic based photovoltaic peak power tracking control "

By Simoes, M.G. ; PMC/Mechatronics, Sao Paulo Univ., Brazil ; Franceschetti, N.N. ; Friedhofer, M.

Review:This paper describes the analysis, modeling and implementation of a fuzzy based photovoltaic peak power tracking system. The maximum power of a photovoltaic system changes with temperature, solar intensity and load. An analytical model is built for the solar cell on the basis of the manufacturer characteristics. The solar panel is integrated with the converter model and a fuzzy algorithm is developed so as to perform an on-line search procedure to track the maximum power continuously. The system is implemented by an inexpensive RISC microcontroller. Experimental results have shown excellent performance, robustness with parameter variation, modularity for parallel operation at higher power, and ready to retrofit existing installations

35."An efficient method of MPPT tracking system of a solar powered Uninterruptible Power Supply application "

By Thulasiyammal, C. ; Dept. of ICE, AVC Coll. of Eng., Mayiladuthurai, India ; Sutha, S.

Review:The study deals with an innovative system achieving an alternative source of energy supply from photovoltaic energy system which operates in case of utility power failure and provides continuity of supply even in medical appliances or industrial applications. It is also designed to reduce usage of utility supply which is generated from coals, nuclear having more carbons as outlets, lagging of sources and providing impure power to consumers. But the solar power is a pure and precious resource and no more impure outlets other disadvantages as like high initial cost. But the economical status may be improved in future but we may not have resource to generate power sometimes. So cost criteria can be meeting out in future to generate power from solar energy. The proposed PV system is composed of conventional novel single axis tracking system and PV system with DC-DC boost converter and PWM voltage source inverter. Here the tracking system is designed to get always 12 V dc output. This voltage is taken as input to the proposed method to maximize the output.

36."Design Considerations for Solar Energy Harvesting Wireless Embedded Systems "

By Vijay Raghunathan, Aman Kansal, Jason Hsu, Jonathan Friedman, and Mani Srivastava

Review:Sustainable operation of battery powered wireless embedded systems (such as sensor nodes) is a key challenge, and considerable research effort has been devoted to energy optimization of such systems. Environmental energy harvesting, in particular solar based, has emerged as a viable technique to supplement battery supplies. However, designing an efficient solar harvesting system to realize the potential benefits of energy harvesting requires an in-depth understanding of several factors. For example, solar energy supply is highly time varying and may not always be sufficient to power the embedded system. Harvesting components, such as solar panels, and energy storage elements, such as batteries or ultracapacitors, have different voltage-current characteristics, which must be matched to each other as well as the energy requirements of the system to maximize harvesting efficiency. Further, battery non-idealities, such as self-discharge and round trip efficiency, directly affect energy usage and storage decisions. The ability of the system to modulate its power consumption by selectively deactivating its sub-components also impacts the overall power management architecture. This paper describes key issues and tradeoffs which arise in the design of solar energy harvesting, wireless embedded systems and presents the design, implementation, and performance evaluation of Heliomote, our prototype that addresses several of these issues. Experimental results demonstrate that Heliomote, which behaves as a plug-in to the Berkeley/Crossbow motes and autonomously manages energy harvesting and storage, enables near-perpetual, harvesting aware operation of the sensor node.

37."Self-Powered Wireless Sensor Networks for Remote Patient Monitoring in Hospitals "

By Abhiman Hande , Todd Polk, William Walker and Dinesh Bhatia

Review: Patient vital sign monitoring within hospitals requires the use of non-invasivesensors that are hardwired to bedside monitors. This set-up is cumbersome, forcing thepatient to be confined to his hospital bed thereby not allowing him to move around freelywithin the hospital premises. This paper addresses the use of wireless sensor networks formonitoring patient vital sign data in a hospital setting. Crossbow MICAz motes have beenused to design a robust mesh network that routes patient data to a remote base station withinthe hospital premises. A hospital care giver can have access to this data at any point in timeand doesn’t have to be physically present in the patient’s room to review the readings. Thenetwork infrastructure nodes are self-powered and draw energy from overhead 34Wfluorescent lights via solar panels. The sensor nodes can be interfaced to a variety of vitalsign sensors such as electrocardiograms (ECGs), pulse-oximeters and blood pressure (BP)sensors. In order to verify a completely functioning system, a commercial BP/heart-ratemonitor (BPM) was interfaced to a wireless sensor node. The sensor node controls the BPMto initiate a reading, then collects the data and forwards it to the base station. An attractivegraphical user interface (GUI) was designed to store and display patient data on the basestation PC. The set-up was found to be extremely robust with low power consumption.

38."Solar Energy Harvesting for Wireless Sensor Networks "

By Bhuvaneswari, P.T.V. ; MITWSN Lab., Anna Univ., Chennai, India ; Balakumar, R. ; Vaidehi, V. ; Balamuralidhar, P.

Review:The commercially available sensor nodes are battery-driven devices. A number of nodes together constitute a network. As days proceed, the batteries used in the nodes lose their charge and subsequently get isolated from the network. Many energy harvesting schemes have been proposed to alleviate this problem. In this paper, a solar energy based energy harvesting scheme is proposed. This scheme works on the principle of photo-voltaic effect. A recharging circuitry is also designed, that recharges the batteries of the nodes when the charge drops below a threshold level. This leads to strengthening the lifetime of the nodes as well as the network. Compatibility and low power design are the two major salient features of the designed circuitry. The performance of the circuit is also tested with the MICAz hardware.

39."Everlast: Long-life, Supercapacitor-operated Wireless Sensor Node "

By Simjee, F. ; Center for Embedded Comput. Syst., California Univ., Irvine, CA ; Chou, P.H.

Review:This paper describes a supercapacitor-operated, solar-powered wireless sensor node called Everlast. Unlike traditional wireless sensors that store energy in batteries, Everlast's use of supercapacitors enables the system to operate for an estimated lifetime of 20 years without any maintenance. The novelty of this system lies in the feedforward, PFM (pulse frequency modulated) converter and open-circuit solar voltage method for maximum power point tracking, enabling the solar cell to efficiently charge the supercapacitor and power the node. Experimental results show that Everlast can achieve low power consumption, long operational lifetime, and high transmission rates, something that traditional sensor nodes cannot achieve simultaneously and must trade-off

40."Indoor solar energy harvesting for sensor network router nodes "

By Abhiman Hande,Todd Polk,William Walker,Dinesh Bhatia

Review:A unique method has been developed to scavenge energy from monocrystaline solar cells to power wireless router nodes used in indoor applications. The system’s energy harvesting module consists of solar cells connected in series-parallel combination to scavenge energy from 34W fluorescent lights. A set of ultracapacitors were used as the energy storage device. Two router nodes were used as a router pair at each route point to minimize power consumption. Test results show that the harvesting circuit which acted as a plug-in to the router nodes manages energy harvesting and storage, and enables near-perpetual, harvesting aware operation of the router node.

41."200 W low cost module integrated utility interface for modular photovoltaic energy systems "

By Andersen, M. ; MA Consult, Aalborg, Denmark ; Alvsten, B.

Review:This paper describes the design of a utility interface for a 200 W solar cell array. The interface comprises high frequency soft switching PWM power conversion, analog and logic control and protection circuits and an analog maximum power point tracker (MPPT). All circuits are implemented with standard components (no microcontroller) and thus facilitates integration into ASIC components at a later development stage. The design emphasis is on module integration, low cost production and compliance with standards on utility interfacing. The special requirements of utility interfacing and solar cell array utilization are described and the design of the components of the utility interface is described. The theory and design are verified with the implemented laboratory prototype, which shows excellent performance and verifies the operation of the interface

42."Low cost photovoltaic modules based on dye sensitized nanocrystalline titanium dioxide and carbon powder "

By Andreas Kay, Michael Graitzel

Review:A new type of photovoltaic module based on monolithically series connected dye sensitized photoelectrochemical cells is described. Each solar cell element consists of three porous layers on a transparent conducting substrate, namely a photoelectrode of dye sensitized nanocrystalline TiO 2 (anatase), a spacer of electrically insulating, light reflecting particles of TiO 2 (rutile), and a counterelectrode of graphite powder and carbon black. The pores of these layers are filled with a redox electrolyte containing iodide for hole transport between photo- and counterelectrode. The monolithic series connection on the transparent conducting substrate, e.g., SnO 2 coated glass, is achieved by simple overlap of each carbon counterelectrode with the back contact of the adjacent photoelectrode. Such modules may be produced in a continuous non-vacuum process by simple printing techniques. In this paper we present the first results on energy conversion efficiency and long term stability obtained with this new type of solar cell.