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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."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.

4."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

5."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.

6."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.

7."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.

8."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

9."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

10."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

11."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

12."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.

13."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

14."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

15."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.

16."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.

17."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.

18."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.

19."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

20."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.

22."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

23."[ 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.

20."[ 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.

====20."[ 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. � 2011 Elsevier Ltd. All rights reserved.

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 ====20."[ Status of thin film solar cells in research, production and the market ]" ====
 ''' By Arnulf Ja¨ger-Waldau ''' <br /><br />
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 ====20."[ Maximum power point tracking without current sensor for
 photovoltaic module integrated converter using Zigbee wireless
-network ]" ====
+network ]"====
 ''' By Sol Moon, Seong-Jin Kim, Jeong-Won Seo, Joung-Hu Park ⇑, Changkun Park, Chan-Su Chung ''' <br /><br />
 '''Review''':In this paper, a simple maximum power point tracking method for series-connected DC–DC converter