Showing papers on "Solar power published in 2012"

Materials interface engineering for solution-processed photovoltaics

Abstract: Advances in solar photovoltaics are urgently needed to increase the performance and reduce the cost of harvesting solar power. Solution-processed photovoltaics are cost-effective to manufacture and offer the potential for physical flexibility. Rapid progress in their development has increased their solar-power conversion efficiencies. The nanometre (electron) and micrometre (photon) scale interfaces between the crystalline domains that make up solution-processed solar cells are crucial for efficient charge transport. These interfaces include large surface area junctions between photoelectron donors and acceptors, the intralayer grain boundaries within the absorber, and the interfaces between photoactive layers and the top and bottom contacts. Controlling the collection and minimizing the trapping of charge carriers at these boundaries is crucial to efficiency.

Battery Energy Storage for Enabling Integration of Distributed Solar Power Generation

Abstract: As solar photovoltaic power generation becomes more commonplace, the inherent intermittency of the solar resource poses one of the great challenges to those who would design and implement the next generation smart grid. Specifically, grid-tied solar power generation is a distributed resource whose output can change extremely rapidly, resulting in many issues for the distribution system operator with a large quantity of installed photovoltaic devices. Battery energy storage systems are increasingly being used to help integrate solar power into the grid. These systems are capable of absorbing and delivering both real and reactive power with sub-second response times. With these capabilities, battery energy storage systems can mitigate such issues with solar power generation as ramp rate, frequency, and voltage issues. Beyond these applications focusing on system stability, energy storage control systems can also be integrated with energy markets to make the solar resource more economical. Providing a high-level introduction to this application area, this paper presents an overview of the challenges of integrating solar power to the electricity distribution system, a technical overview of battery energy storage systems, and illustrates a variety of modes of operation for battery energy storage systems in grid-tied solar applications. The real-time control modes discussed include ramp rate control, frequency droop response, power factor correction, solar time-shifting, and output leveling.

History, Evolution, and Future Status of Energy Storage

Abstract: Advanced energy storage has been a key enabling technology for the portable electronics explosion. The lithium and Ni-MeH battery technologies are less than 40 years old and have taken over the electronics industry and are on the same track for the transportation industry and the utility grid. In this review, energy storage from the gigawatt pumped hydro systems to the smallest watt-hour battery are discussed, and the future directions predicted. If renewable energy, or even lower cost energy, is to become prevalent energy storage is a critical component in reducing peak power demands and the intermittent nature of solar and wind power. An electric economy will demand more electrification of the transportation sector and it is likely that all vehicles sold by the end of this decade will have some level of hybridization. Energy storage capabilities in conjunction with the smart grid are expected to see a massive leap forward over the next 25 years.

Renewable energy technologies: cost analysis series

Abstract: Renewable energy technologies: cost analysis series. Bonn : IRENA, June 2012 http://www.irena.org/menu/index.aspx?mnu=cat&PriMenuID=36&CatID=128 Preface : International Renewable Energy Agency (IRENA) Member Countries have asked for better, objective cost data for renewable energy technologies.These five reports on solar pholtovoltaics, wind, biomass, hydropower and concentrating solar power address the current costs of these key renewable power technology options.The reports provide valuable...

Operational Water Consumption and Withdrawal Factors for Electricity Generating Technologies: A Review of Existing Literature

Abstract: This report provides estimates of operational water withdrawal and water consumption factors for electricity generating technologies in the United States. Estimates of water factors were collected from published primary literature and were not modified except for unit conversions. The water factors presented may be useful in modeling and policy analyses where reliable power plant level data are not available. Major findings of the report include: water withdrawal and consumption factors vary greatly across and within fuel technologies, and water factors show greater agreement when organized according to cooling technologies as opposed to fuel technologies; a transition to a less carbon-intensive electricity sector could result in either an increase or a decrease in water use, depending on the choice of technologies and cooling systems employed; concentrating solar power technologies and coal facilities with carbon capture and sequestration capabilities have the highest water consumption values when using a recirculating cooling system; and non-thermal renewables, such as photovoltaics and wind, have the lowest water consumption factors. Improved power plant data and further studies into the water requirements of energy technologies in different climatic regions would facilitate greater resolution in analyses of water impacts of future energy and economic scenarios. This report provides the foundation for conducting water use impact assessments of the power sector while also identifying gaps in data that could guide future research.

Platform Architecture for Solar, Thermal, and Vibration Energy Combining With MPPT and Single Inductor

Abstract: A platform architecture combining energy from solar, thermal, and vibration sources is presented. A dual-path architecture for energy harvesting is employed that has a peak efficiency improvement of 11%-13% over the traditional two-stage approach. The system implemented consists of a reconfigurable multi-input, multi-output switch matrix that combines energy from three distinct energy-harvesting sources-photovoltaic, thermoelectric, and piezoelectric. The system can handle input voltages from 20 mV to 5 V and is capable of extracting maximum power from individual harvesters all at the same time utilizing a single inductor. A proposed time-based power monitor is used for achieving maximum power point tracking for the photovoltaic harvester. This has a peak tracking efficiency of 96%. The peak efficiencies achieved with inductor sharing are 83%, 58%, and 79% for photovoltaic boost, thermoelectric boost, and piezoelectric buck-boost converters, respectively. The switch matrix and the control circuits are implemented on a 0.35-μm CMOS process.

Control and Circuit Techniques to Mitigate Partial Shading Effects in Photovoltaic Arrays

Abstract: Partial shading in photovoltaic (PV) arrays renders conventional maximum power point tracking (MPPT) techniques ineffective. The reduced efficiency of shaded PV arrays is a significant obstacle in the rapid growth of the solar power systems. Thus, addressing the output power mismatch and partial shading effects is of paramount value. Extracting the maximum power of partially shaded PV arrays has been widely investigated in the literature. The proposed solutions can be categorized into four main groups. The first group includes modified MPPT techniques that properly detect the global MPP. They include power curve slope, load-line MPPT, dividing rectangles techniques, the power increment technique, instantaneous operating power optimization, Fibonacci search, neural networks, and particle swarm optimization. The second category includes different array configurations for interconnecting PV modules, namely series-parallel, total-cross-tie, and bridge-link configurations. The third category includes different PV system architectures, namely centralized architecture, series-connected microconverters, parallel-connected microconverters, and microinverters. The fourth category includes different converter topologies, namely multilevel converters, voltage injection circuits, generation control circuits, module-integrated converters, and multiple-input converters. This paper surveys the proposed approaches in each category and provides a brief discussion of their characteristics.

Advancement in solar photovoltaic/thermal (PV/T) hybrid collector technology

Abstract: This article presents an overview on the research and development and application aspects for the hybrid photovoltaic/thermal (PV/T) collector systems. A major research and development work on the photovoltaic/thermal (PVT) hybrid technology has been done since last 30 years. Different types of solar thermal collector and new materials for PV cells have been developed for efficient solar energy utilization. The solar energy conversion into electricity and heat with a single device (called hybrid photovoltaic thermal (PV/T) collector) is a good advancement for future energy demand. This review presents the trend of research and development of technological advancement in photovoltaic thermal (PV/T) solar collectors and its useful applications like as solar heating, water desalination, solar greenhouse, solar still, photovoltaic–thermal solar heat pump/air-conditioning system, building integrated photovoltaic/thermal (BIPVT) and solar power co-generation.

U.S. Renewable Energy Technical Potentials: A GIS-Based Analysis

Abstract: This report presents the state-level results of a spatial analysis effort calculating energy technical potential, reported in square kilometers of available land, megawatts of capacity, and gigawatt-hours of generation, for six different renewable technologies. For this analysis, the system specific power density (or equivalent), efficiency (capacity factor), and land-use constraints were identified for each technology using independent research, published research, and professional contacts. This report also presents technical potential findings from previous reports.

The Market Value of Variable Renewables

Abstract: The income that wind and solar power receive on the market is affected by the variability of their output. At times of high availability of the primary energy source, they supply electricity at zero marginal costs, shift the supply curve (merit-order curve) to the right and thereby reduce the equilibrium price of electricity during that hour. The size of this merit-order effect depends on the amount of installed renewable capacity, the slope of the merit-order curve, and the intertemporal flexibility of the electricity system. Thus the price of wind power falls with higher penetration rates, even if the average electricity price remains constant. This work quantifies the effect of variability on the market value of renewables using a calibrated model of the European electricity market. The relative price of German wind power (value factor) is estimated to fall from 110% of the average electricity price to 50% as generation increases from zero to 30% of total consumption. For solar power, the drop is even sharper. Hence competitiveness for large-scale renewables deployment will be more difficult to accomplish than often believed.

System Advisor Model, SAM 2011.12.2: General Description

Abstract: This document describes the capabilities of the U.S. Department of Energy and National Renewable Energy Laboratory's System Advisor Model (SAM), Version 2013.9.20, released on September 9, 2013. SAM is a computer model that calculates performance and financial metrics of renewable energy systems. Project developers, policy makers, equipment manufacturers, and researchers use graphs and tables of SAM results in the process of evaluating financial, technology, and incentive options for renewable energy projects. SAM simulates the performance of photovoltaic, concentrating solar power, solar water heating, wind, geothermal, biomass, and conventional power systems. The financial model can represent financial structures for projects that either buy and sell electricity at retail rates (residential and commercial) or sell electricity at a price determined in a power purchase agreement (utility). SAM's advanced simulation options facilitate parametric and sensitivity analyses, and statistical analysis capabilities are available for Monte Carlo simulation and weather variability (P50/P90) studies. SAM can also read input variables from Microsoft Excel worksheets. For software developers, the SAM software development kit (SDK) makes it possible to use SAM simulation modules in their applications written in C/C++, C#, Java, Python, and MATLAB. NREL provides both SAM and the SDK as free downloads at http://sam.nrel.gov. Technical supportmore » and more information about the software are available on the website.« less

Intertwined aligned carbon nanotube fiber based dye-sensitized solar cells.

Abstract: Metal wires suffer from corrosion in fiber-shaped dye-sensitized solar cells (DSSCs). We report herein that stable, ultrastrong, and highly flexible aligned carbon nanotube fibers can be used not only as catalytic counter electrodes but also as conductive materials to support dye-loaded TiO(2) nanoparticles in DSSCs. The power conversion efficiency of this fiber solar cell can achieve 2.94%. These solar power fibers, exhibiting power conversion efficiency independent of incident light angle and cell length, can be woven into textiles via a convenient weaving technology.

Solar energy in India: Strategies, policies, perspectives and future potential

Abstract: Renewable energy sources and technologies have potential to provide solutions to the longstanding energy problems being faced by the developing countries like India. Solar energy can be an important part of India's plan not only to add new capacity but also to increase energy security, address environmental concerns, and lead the massive market for renewable energy. Solar thermal electricity (STE) also known as concentrating solar power (CSP) are emerging renewable energy technologies and can be developed as future potential option for electricity generation in India. In this paper, efforts have been made to summarize the availability, current status, strategies, perspectives, promotion policies, major achievements and future potential of solar energy options in India.

The Prospects for Cost Competitive Solar PV Power

Abstract: New solar Photovoltaic (PV) installations have grown globally at a rapid pace in recent years. We provide a comprehensive assessment of the cost competitiveness of this electric power source. Based on data available for the second half of 2011, we conclude that utility-scale PV installations are not yet cost competitive with fossil fuel power plants. In contrast, commercial-scale installations have already attained cost parity in the sense that the generating cost of power from solar PV is comparable to the retail electricity prices that commercial users pay, at least in certain parts of the U.S. This conclusion is shown to depend crucially on both the current federal tax subsidies for solar power and an ideal geographic location for the solar installation. Projecting recent industry trends into the future, we estimate that utility-scale solar PV facilities are on track to become cost competitive by the end of this decade. Furthermore, commercial-scale installations could reach “grid parity” in about ten years, if the current federal tax incentives for solar power were to expire at that point.

Impacts of intermittent renewables on electricity generation system operation

Abstract: All power generation technologies leave their particular imprint on the power system that they belong to. Wind and solar power have only recently reached significant levels of penetration in some countries, but they are expected to grow much during the next few decades, and contribute substantially to meeting future electricity demand, see e.g. European Commission (2011). Wind, photovoltaic (PV) solar and concentrated solar power (CSP) with no storage have non-controllable variability, partial unpredictability and locational dependency. These attributes make an analysis of their impacts on electricity generation system operation and design particularly interesting. This paper reviews how a strong presence of intermittent renewable generation will change how future power systems are planned, operated and controlled. The change is already noticeable in countries that currently have a large penetration of wind and solar production. The mix of generation technologies, and potentially market rules, will have to adapt to accommodate this presence. Regulatory adjustments might be needed to attract investment in "well adapted" technologies. This paper identifies open issues that deserve further analysis from a technical, economic and regulatory perspective.

Electrochemical Hydrogen Evolution: Sabatier's Principle and the Volcano Plot

Abstract: The electrochemical hydrogen evolution reaction (HER) is growing in significance as society begins to rely more on renewable energy sources such as wind and solar power. Thus, research on designing...

Pole-mounted power generation systems, structures and processes

Abstract: Solar power systems and structures are mountable to a power distribution structure, e.g. a power pole or tower, which supports alternating current (AC) power transmission lines. An exemplary power generation structure is fixedly attached to and extends from the power distribution structure, and comprises a mounting rack. A solar array, comprising at least one solar panel, is affixed to the mounting rack. A DC to AC invertor is connected between the DC outputs of the solar array and the AC power transmission lines. The length of the solar array is generally in alignment with the power distribution structure, and the width of the solar array is greater than half the circumference of the power distribution structure. The mounting rack and solar array may preferably be rotatable, such as based on any of location, time of day, or available light.

Molten-Salt Power Towers: Newly Commercial Concentrating Solar Storage

Abstract: Molten-salt storage is already commercially available for concentrating solar power (CSP) plants, allowing solar power to be produced on demand and to “backup” variable renewable sources such as wind and photovoltaics. The first CSP plants to operate commercially with molten-salt storage utilized parabolic trough concentrators, for example, the Andasol-1 plant. A new type of storage plant has now reached commercial status, with the 19.9-MWe Torresol Gemasolar power tower, featuring 15 h of molten-salt storage, having come online in Spain in May 2011. Advantages of the power tower storage system include the elimination of heat transfer oil and associated heat exchangers, a lower salt requirement, higher steam cycle efficiency, better compatibility with air cooling, improved winter performance, and simplified piping schemes. Near-term advances in molten-salt power tower technology include planned up-scaling, with SolarReserve due to begin constructing a 110-MWe plant in Nevada by August 2011. Other advances include improvements to the thermal properties of molten salts and the development of storage solutions in a single tank. With these developments at hand, CSP will continue to provide dispatchable solar power, with the capacity to provide energy storage for 100% renewable electricity grids in sun-belt countries.

A review of concentrating solar power plants in the world and their potential use in Serbia

Abstract: In the paper description and working principles of the parabolic trough power plants, solar tower power plants, parabolic dish power plants and power plants with Fresnel reflectors in the world and their potential use in Serbia are given. In addition, the examples and technical characteristics of some concentrating solar power plants in the world are given. The paper points out that first CSP plant Solar One was installed in 1982 in USA. Nowadays there are 29 active CSP plants while 31 are being constructed worldwide. Power of parabolic trough power plants is between 0.25 and 354 MW, solar tower power plants 1.5 and 20 MW, parabolic dish power plants 1.5 MW and power plants with Fresnel reflectors 1.4 and 5 MW. The biggest active CSP plant SEGS of 354 MW is located in Mojave Desert in USA. Besides results of considerations on solar energy potential in Serbia, current solar energy activities and future solar power projects in Serbia are given. Special attention is drawn to the Serbian government initiatives and support for the use of renewable sources of energy. In the end a suggestion for the installation of concentrating solar power plant in Serbia is given.

Control of Solar Energy Systems

Abstract: This work deals with the main control problems found in solar power systems and the solutions proposed in literature. The paper first describes the main solar power technologies, its development status and then describes the main challenges encountered when controlling solar power systems. While in other power generating processes, the main source of energy can be manipulated, in solar energy systems, the main source of power which is solar radiation cannot be manipulated and furthermore it changes in a seasonal and on a daily base acting as a disturbance when considering it from a control point of view. Solar plants have all the characteristics needed for using industrial electronics and advanced control strategies able to cope with changing dynamics, nonlinearities and uncertainties.

Exergy analysis of solar energy applications

Abstract: Solar energy is a clean, abundant and easily available renewable energy. Usage of solar energy in different kinds of systems provides scope for several studies on exergy analysis. In the present work, a comprehensive literature review has been carried out on exergy analysis of various solar energy systems. The systems considered under study are solar photovoltaic, solar heating devices, solar water desalination system, solar air conditioning and refrigerators, solar drying process and solar power generation. The summary of exergy analysis and exergetic efficiencies is presented along with the exergy destruction sources.

Supercritical carbon dioxide power cycle configuration for use in concentrating solar power systems

Abstract: Methods and solar power generation systems including a working fluid circuit providing for the flow of supercritical carbon dioxide (S-CO2) therein. The methods and systems may also include a solar energy receiver in thermal communication with the working fluid circuit providing for solar heating of the S-CO2 working fluid; a power turbine in fluid communication with the S-CO2; a generator mechanically coupled to the power turbine; a compressor turbine in fluid communication with the S-CO2 and a compressor mechanically coupled to the compressor turbine such that the compressor is configured to compress the S-CO2 within a portion of the working fluid circuit. The methods and systems may optionally include a secondary power block in thermal communication with a primary power block. The methods and systems may optionally include thermal energy storage. Various embodiments may be implemented in a modular fashion and located on or within a solar energy tower.

Switch: a planning tool for power systems with large shares of intermittent renewable energy.

Abstract: Wind and solar power are highly variable, so it is it unclear how large a role they can play in future power systems. This work introduces a new open-source electricity planning model—Switch—that i...