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Fault current studies are often required to determine the proper settings for the overcurrent relays. The conventional synchronous generators are known to exhibit high current magnitude during fault, which present an ideal scenario for fault isolation using the cost-effective overcurrent relays. On the other hand, the fault current magnitude from renewable based generation such as solar photovoltaic (PV) is intentionally limited due to the constraints in the power electronic components. Therefore, dispute pertaining to the feasibility of overcurrent relay in inverter based distributed generations (IBDG) applications arises. These disputes mainly arise due to the unavailability of firm understanding of the fault current characteristics from the IBDGs. The problem is further compounded with the availability of numerous possible fault current controls, where various fault current characteristics can be obtained from the IBDGs. In light of this problem, this paper aims to establish the various possible IBDG fault current characteristics, with special attention paid to compliance to the latest grid codes requirements such as low voltage ride through (LVRT) with reactive current injection (RCI). Five different types of RCI controls are analyzed as follows: variable active current control, constant active power control, constant reactive power control, constant active current control, and maximum current control. From the established fault current characteristics in this paper, the disputes pertaining to the feasibility of overcurrent relay for IBDG applications can be resolved and the suitable types of RCI control that allow satisfactory performance of overcurrent relays can be identified. [ABSTRACT FROM AUTHOR]

Electrical energy becomes necessary for human being. Generation of electrical energy mostly depends on fossils fuel, they are limited in nature and also responsible for environmental pollution. Renewable energy resources provides a better alternative for future,In comparison to conventional energy resources economical aspect is a major issue of renewable energy sources with the feasibility and efficiency. These limitations are tried to overcome by deployment hybrid renewable energy resources. There are certain criteria to analyze and implement the sized, optimized and cost efficient system. This paper focus on hybrid energy systems based on solar photovoltaic (PV) and wind resources. This paper shed lights on various parameters of economic feasibility, sizing strategies with logical advancements to enhance their utilization, future prospects, and their arrangement. Strategies to develop an effective storage system is also presented here.A brief review on developments in optimization techniques, reliability index and cost analyzing techniques for hybrid renewable energy systems are also presented. [ABSTRACT FROM AUTHOR]

This paper presents a multi-objective model for expansion with a high share of renewable energy. The model considers three objective functions (minimizing the total cost, maximizing generation at the peak load, and maximizing the contribution of non-hydro renewable sources). The model was then applied to the Brazilian case, using the new government targets for renewable energy. The introduction of the objectives regarding peak load and non-hydro renewable generation lead to an increase of solar power generation. In many studies about Brazil, solar power was not considered, or its participation was negligible, but in this paper the results show solar energy as the main non-hydro renewable source in 2030, due to its capacity to meet the peak demand, since its daily curve coincides with the peak load period. In this study, it was possible to meet 90% of the annual load with renewable sources (with 23% being ensured by non-hydro) and the solar power increased from 21 MW to 40000 MW by 2030. [ABSTRACT FROM AUTHOR]

Today solar power is still dominantly presented to be expensive source of electricity. However, the profitability of solar and other electricity generation technologies is typically evaluated with the Levelized Cost of Electricity (LCOE) approach. This paper questions the traditional investment evaluation logics of power production (LCOE) in the interesting case of rooftop PVs and based on customer value generation logics presents a new approach for evaluating the profitability of rooftop PV investments. The approach recognizes the value that PVs produce to real estate owners and utilize basic real estate investment models to evaluate the profitability of PVs. The results imply that, if PVs are considered as a part of the underlying property, rooftop PV systems are already today profitable in many European cities and can provide substantial returns on investment for property owners. More interestingly, the results imply that rooftop PV investments are most profitable in the dense urban cores instead of more remote (industrial) locations, and thus the current trend of urbanization seems to further strengthen the profitability of rooftop solar power. This paper points out that spatial locations drive the economic analysis of real estate, and thus it is likely that it will drive the economic analysis of decentralized on-site energy investments as well. [ABSTRACT FROM AUTHOR]

India with a fast growing demand for electricity and increasing consideration to emissions reduction is investing strongly in renewable electricity generation. Among renewables, the Central and State Governments have set aspirational targets for on-grid solar electricity and legislated several supporting policies to realise these targets. As a result of the favourable political environment, the development of on-grid solar, in terms of the rate of growth in installed capacity, has been increasing in the recent years, and it is expected to continue in the future. This paper aims to investigate the impact of historical transitions of India's electricity sector on the ongoing development of on-grid solar electricity and to explore the prospect of solar sector development in the future. First of all, we investigate how the historical transformation of governmental intervention's approach intertwined with the gradual shift of the source of generation has paved the way for the current achievements in on-grid solar electricity. Second, we envision the future challenges and opportunities for the development of solar sector by looking ahead and discussing the continuity of government's support and the prospective competitions between different sources. We conclude the paper with some required steps to be taken in order to secure the achievement of the targets in solar electricity in the future. [ABSTRACT FROM AUTHOR]

The utilization of solar energy based technologies has attracted increased interest in recent times in order to satisfy the various energy demands of our society. This paper presents a thorough review of the open literature on solar energy based heat and power plants. In order to limit the scope of the review, only fully renewable plants with at least the production of electricity and heat/hot water for end use are considered. These include solar photovoltaic and solar thermal based plants with both concentrating and non-concentrating collectors in both solar-only and solar-hybrid configurations. The paper also presents a selection of case studies for the evaluation of solar energy based combined heat and power generation possibility in Denmark. The considered technologies for the case studies are (1) solar photovoltaic modules, (2) solar flat plate collectors, (3) a ground source heat pump, (4) a biomass burner, and (5) an organic Rankine cycle. The various cases are compared on the basis of economic profitability and environmental performance. The results from the case studies indicate that it is economically and environmentally beneficial to invest in both small and large capacity solar-biomass hybrid plants for combined heat and power production in the Nordic climatic conditions. The results also suggest that the configuration with an organic Rankine cycle with solar thermal collectors and a biomass burner is particularly attractive for large capacity plants. [ABSTRACT FROM AUTHOR]

Nowadays, renewable energies are more preferable to fossil fuels because of being free, widely available and producing minimal pollution. One of the disadvantages of renewable energy systems is that using only one type of renewable energy cannot guarantee a continuous power generation. To overcome this problem, two or more renewable energy systems should be used simultaneously to compensate for times when one of them is not available or the renewable system should be used aligned with the generator. In addition, another weakness is that they are not accessible in every geographical position and location. It is clear that renewable energy systems can be exploited to their fullest capacity when used in the proper place. Therefore, given the importance of finding suitable places for co-utilization of several renewable energies, present paper attempted to find the ideal locations for construction of hybrid solar-wind power stations in Middle-East using Boolean model in GIS software. The Boolean method is, in a way, a more stringent method compared to the other positioning methods. Therefore, the selected locations will definitely have greater energy potential by using the Boolean method. Data obtained by RETScreen4 software from 400 stations in Middle-East were used for collecting monthly weather information. Results of the current paper may be helpful in creating prospects for sustainable energy development for systems based on natural resources and facilitating the national power transmission and sustainable environmental policies. [ABSTRACT FROM AUTHOR]

The penetration of photovoltaics (PV’s) in electric power generation is continually increasing. Tracking maximum power point in PV systems is an important task and represents a challenging problem. In maximum power point tracking (MPPT), the duty cycle of DC-DC converter is adjusted in a way that maximum achievable power is extracted from PV system. In this paper, the existing MPPT strategies are classified into two main categories and the strategies of each category are reviewed. Based on the conducted review, some directions for future research are recommended. The author strongly believes that this paper will be helpful for researchers and engineers in the field of PV systems. [ABSTRACT FROM AUTHOR]

Abstract Fuel cells and solar energy are promising candidates for electricity generation. It is forecast that fuel cells and solar power systems will play an important role in reducing the greenhouse gas footprint and replacing fossil fuels. Therefore, the limitations of fuel cells and solar power systems, such as low efficiency, high cost, and low reliability, must be addressed appropriately to enable their full potentials. Metal foam is a new class of material that has gained immense attention due to its excellent properties suitable for a wide range of applications. Its unique characteristics distinguish it from typical solid metals. The properties of metal foam can be modified during the fabrication stage by manipulating its physical structure. The goal of this paper is to review the application of metal foam in fuel cells and solar power systems. Besides, the performance of metal foam in fuel cells and solar systems is also discussed. Metal foam has been applied to the electrodes, gas diffusion layer and flow field of fuel cells to enhance performance, especially in regard to current density and flow distribution. Furthermore, metal foam is a heat exchanger for the solar energy harvesting system to improve its efficiency. Superior performances in experimental testing allows the possibility of commercialization of metal foam products in the renewable energy field. Highlights • This article reviews the past research on metal foam in fuel cell and solar power systems. • Metal foam applications on bipolar plates, electrodes and the gas diffusion layer in a fuel cell. • Metal foam as a thermal management system in solar power systems. • Barriers and future perspectives of metal foam applications in fuel cells and solar power systems. [ABSTRACT FROM AUTHOR]

As Iran is rich in oil and gas resources, renewable energy was known as a luxurious source of electric power generation for a long time. New policies and targeted subsidy reform plan for fossil fuel products have changed the view of decision-makers and energy sector investors toward renewable energy resources. According to the climatological studies, two-thirds of Iran's land has three hundred sunny days which indicates great potentials for providing solar energy. This paper deals with small-scale solar energy potentials in different cities of Iran. The considered solar systems are based on the combination of photovoltaic panels in order to obtain the nominal values of 1, 5 and 10 kW for 15 selected cities of Iran. Design of the photovoltaic (PV) systems is carried out based on optimum fixed tilt angles of the panels and efficiency variation due to the temperature changes of different locations. The final decision on financial assessment of the mentioned solar PV projects is based on different concepts of engineering economy such as rate of return (ROR), present worth of benefit and cost (PWB, PWC), extra investment analysis, levelized cost of energy (LCOE). The amount of calculated income and the expected benefit are also investigated under certainty and uncertainty of guaranteed solar electricity purchase tariff in a 30-year project lifetime. [ABSTRACT FROM AUTHOR]

Multi-criteria decision making (MCDM) methods are becoming increasingly popular in solving energy selection problems because these problems involve multiple and often conflicting criteria. This paper presents comparative analysis of ranking renewable energy sources (RES) for electricity generation in Taiwan using four MCDM methods - WSM, VIKOR, TOPSIS, and ELECTRE. The Shannon entropy weight method is used to assess the importance of each criterion for the ranking of RES. After that, four MCDM methods are utilized for quantitative evaluation to rank all available RE alternatives. From the weights estimation results, efficiency is the first priority in all evaluation criteria, followed by job creation, operation, and maintenance cost. The purpose of this study is to rank the priorities of various RES and propose recommendations for Taiwan's RE development. The ranking results show that hydro is the best alternative in Taiwan, followed by solar, wind, biomass and geothermal. Furthermore, sensitivity analysis of the weights was conducted considering the ranking results heavily depend on the criteria weight. The results of sensitivity analysis indicated that when financial or technical aspects are focused upon, hydropower is the best RES because its technology is the most mature and the cost is the lowest in Taiwan. In addition, from an environmental perspective, wind energy is the best choice, and from the social perspective, solar PV is the best choice. The findings of this study can provide useful information to energy decision makers and serve as a reference for Taiwan's energy policy. [ABSTRACT FROM AUTHOR]

In present day scenario, the focus is reallocating towards integration of small and medium scale power plants based on renewable energy sources into the power distribution system. Solar is the fastest growing form of renewable energy and a single phase voltage source inverter is used to interface photovoltaic based plants with the distribution system. The grid integrated inverter has stringent control requirements. A current controller is employed to mitigate the harmonics in the current injected into the grid and regulate the power exchange between the plant and the grid. This paper presents a review of the current control strategies implemented for a single phase grid tied photovoltaic inverter. A comparative performance evaluation of the current control techniques is also presented through simulation and experimental results. [ABSTRACT FROM AUTHOR]

The term “polygeneration” is referred to as “an energy supply system, which delivers more than one form of energy to the final user”, for example: electricity, heating/cooling, desalination can be delivered from polygeneration process. The polygeneration demonstrates unique integration of energy efficiency and renewable energy. It is the next generation energy production technique with a potential to overcome intermittence of renewable energy, reduce cost of power generation and greenhouse gas emissions. The feasibility study of this paper is divided in three sections: In first section of this study, solar and biomass have been arranged to produce steam for power generation. In the second section, cooling is produced by vapor absorption refrigeration (VAR; LiBr-H 2 O) system as per demand load requirement using steam, extracted from pass-out turbine. In the last section of this paper, multi effect dehumidification (MED) water desalination is produced by using limited amount of heat from water vapor (refrigerant; H 2 O) through HE1 of VAR cooling system. [ABSTRACT FROM AUTHOR]

Solar PV has been a cornerstone for the energy policy makers around the globe. It is because the environmental effects of solar energy are low as compared to the conventional energy sources. It is free and virtually inexhaustible. Developed countries have long been in the business of using solar energy for energy generation. However, for the third world countries like Pakistan, the use of solar energy for power generation is a relatively new experience. In recent months, Pakistan has shown a paradigm shift in its renewable energy policy and invested on mega power plants based on solar PV system. This paper reviews the recent exponential rise of using solar energy for power generation in Pakistan. The results of this paper will not only help in understanding and hence, curbing the power crisis in Pakistan, but will also be relevant to the other countries of the third world. [ABSTRACT FROM AUTHOR]

The Rankine cycle is considered the most common and competitive power generation cycle to produce electricity from solar thermal energy. This paper reviews the work done on the solar Rankine cycle systems for power generation and focuses on the working fluids investigated in the literature and the application of these systems in water pumping and water desalination. [ABSTRACT FROM AUTHOR]

Irrigation is one of the essential unit operations for agriculture and Sudan as an agricultural country with rich natural resources has an urgent need to optimize the utilization of energy, water, and land in a most sustainable way. The cost-effective irrigation pathway utilizing one of the clean energy technologies such as solar energy would contribute significantly to the sustainable development of agricultural sector in Sudan. This paper is intended to investigate the most cost-effective solar water pumping system for irrigation in Sudan. Three solar irrigation pumps were considered based on the collector configuration and type of energy conversion to include two thermal and one photovoltaic pump; parabolic trough pump (PTP), concentrating dish pump (CDP), and photovoltaic pump (PVP). Levelized energy cost (LEC) was used in this study as the economic indicator for the feasibility of solar water pumping systems. A comparative assessment model was developed based on weather conditions of Sudan and sensitivity analysis was conducted to study the effect of design parameters, weather conditions, and interest and inflation rates on the LEC of solar water pumping systems. The resulted LECs for PVP, CDP, and PTP in the base case were found to be 0.033 $/kWh, 0.062 $/kWh, and 0.075 $/kWh, respectively. PVP is the most feasible pathway among solar irrigation pumps in Sudan, and its initial cost per unit hydraulic power capacity is 1351 $/kW, compared to 4072 $/kW and 4884 $/kW for CDP and PTP, respectively. [ABSTRACT FROM AUTHOR]

Poor air quality from coal combustion adversely impacts human health including mortality and morbidity effects on respiratory, cardiovascular, nervous, urinary, and digestive systems. However, the continued use of coal are no longer necessary to provide for society's electrical needs because of advances in solar photovoltaic (PV) technology. In order to inform health policy this paper reviews the data for quantifying the lives saved by a replacement of U.S. coal-fired electricity with solar PV systems. First the geospatial correlation with coal fired power plants and mortality is determined for the U.S. at the state level. Then, current life cycle mortality rates due to coal combustion are calculated and current energy generation data is collated. Deaths/kWh/year of coal and PV are calculated, and the results showed that 51,999 American lives/year could be saved by transitioning from coal to PV-powered electrical generation in the U.S. To accomplish this, 755 GW of U.S. PV installations are needed. The first costs for the approach was found to be roughly $1.45 trillion. Over the 25 year warranty on the PV modules the first cost per life saved is approximately $1.1 million, which is comparable to the value of a human life used in other studies. However, as the solar electricity has value, the cost per life is determined while including the revenue of the solar electric generation using a sensitivity analysis on the value of the electricity. These results found that for most estimations of the value, saving a life by offsetting coal with PV actually saved money as well, in some cases several million dollars per life. It is concluded that it is profitable to save lives in the U.S. with the substitution of coal-fired electricity with solar power and that the conversion is a substantial health and environmental benefit. [ABSTRACT FROM AUTHOR]

Abstract: Many renewable energy policies are looking into new incentives to absorb investments by targeting abating CO2 emission and fixing energy price fluctuation. Feed in Tariff (FIT) is a policy for rebating the amount of generated renewable electricity to investor. FIT is also defined as a CO2 mitigation policy in electricity generation from renewable sources. This paper presents a cost benefit survey that estimates the real produced carbon dioxide for electricity generation in selected countries. This study introduces the substitute price of avoiding CO2 emission as an indicator. The new indicator shows how much is paid for avoiding CO2 by each selected countries through the FIT policy for renewable technologies. The amount calculated for solar energy is taken as a case in this paper. The result confirms that the FIT policy reasonably works for solar energy in absorbing investment. However the FIT policy claims a large portion of liquidity compared with other approaches. Hence makes this mechanism inept as a CO2 mitigation policy. [Copyright &y& Elsevier]

Abstract: Solar energy, at the present time is considered as an important source in electricity generation. Electricity from the solar energy can be generated using solar photovoltaic (PV) modules. The maximization of solar power extracted from a PV module is of special concern as its efficiency is very low. The output power of a PV module is highly dependent on the geographical location and weather conditions such as solar irradiation, shading and temperature. To obtain maximum power from PV module, photovoltaic power system usually requires maximum power point tracking (MPPT) controller. In this paper, an adaptive neuro-fuzzy inference system (ANFIS) based maximum power point tracker for PV module has been presented. To extract maximum power, a DC–DC boost converter is connected between the PV module and the load. The duty cycle of DC–DC boost converter is modified with the help of the ANFIS reference model, so that maximum power is transferred to load. Due to the complexity of the tracker mechanism and non-linear nature of photovoltaic system, the artificial intelligence based technique, especially the ANFIS method, is used in this paper. In order to observe the maximum available power of PV module, the ANFIS reference model directly takes in operating temperature and irradiance level as input. The response of proposed ANFIS based control system shows accuracy and fast response. The simulation result reveals that the maximum power point is tracked satisfactorily for varying irradiance and temperature of PV module. Simulation results are provided to validate the concept. [Copyright &y& Elsevier]

Abstract: Hybrid energy systems are being utilized for supplying electrical energy in urban, rural and remote areas to overcome the intermittence of solar and wind resources. A hybrid renewable energy system incorporates two or more electricity generation options based on renewable energy or fossil fuel unit. The techno-economic analysis of the hybrid system is essential for the efficient utilization of renewable energy resources. Due to multiple generation systems, hybrid system analysis, is quite complex and requires to be analyzed thoroughly. This requires software tools for the design, analysis, optimization, and economic viability of the systems. In this paper, 19 softwares with their main features and current status are presented. The softwares studied are HOMER, Hybrid2, RETScreen, iHOGA, INSEL, TRNSYS, iGRHYSO, HYBRIDS, RAPSIM, SOMES, SOLSTOR, HySim, HybSim, IPSYS, HySys, Dymola/Modelica, ARES, SOLSIM, and HYBRID DESIGNER. The research work related to hybrid systems carried out using these softwares at different locations worldwide is also reviewed. The main objective of the paper is to provide the current status of these softwares to provide basic insight for a researcher to identify and utilize suitable tool for research and development studies of hybrid systems. The capabilities of different softwares are also highlighted. The limitations, availability and areas of further research have also been identified. [Copyright &y& Elsevier]

Abstract: Despite the rapid decline in the cost of solar photovoltaic (PV) systems in the past five years, even recent academic research suggests that the cost of generating PV electricity remains too high for PV to make a meaningful contribution to the generation of grid electricity in developing countries. This assessment is reflected in the views of policymakers throughout Africa, who often consider PV as a technology suited only to remote locations and small-scale applications. This paper therefore analyzes whether, in contrast to conventional wisdom, PV is already competitive with other generation technologies. Analytically, the paper is based on a levelized cost of electricity (LCOE) model to calculate the cost of PV electricity in Kenya, which serves as a case study. Based on actual technology costs and Kenya's solar resource, the LCOE from PV is estimated at USD 0.21/kWh for the year 2011, with scenario results ranging from USD 0.17–0.30/kWh. This suggests that the LCOE of grid-connected PV systems may already be below that of the most expensive conventional power plants, i.e. medium-speed diesel generators and gas turbines, which account for a large share of Kenya's current power mix. This finding implies that researchers and policymakers may be mistaken in perceiving solar PV as a costly niche technology, rather than a feasible option for the expansion of power generation in developing countries. [Copyright &y& Elsevier]

Abstract: The paper focuses on the possibilities of generating electrical energy by means of PV solar plants of 1MW in Serbia. Further on basic physical characteristics of solar cells made of monocryistalline silicon, CdTe and CIS solar cells and a description of the fixed PV solar plants, one-axis and dual-axis tracking PV solar plants are given. The paper proceeds to tackle the legislative frame concerning renewable sources of energy and the current state of the use of PV systems in Serbia, climate conditions and energy potential of the renewable sources in Serbia. Apart from PVGIS solar map of Serbia real meteorological data for 17 towns in Serbia are given. Based on PVGIS program, geographycal position and the results of PVGIS calculation of the yearly average values of the optimal panel inclination, solar irradiation on the horizontal, vertical and optimally inclined plane, ratio of diffuse to global solar irradiation and linke turbidity for some cities in Serbia are given. Total for year sum of global irradiation per square meter received by the modules of the fixed PV solar plants, optimally inclined one-axis and dual-axis tracking PV solar plants of 1MW and total for year electricity production of different types of PV solar plant of 1MW for 23 cities in Serbia obtained by PVGIS are given. Comparison of total for year electricity production of different types of PV solar plant of 1MW with monocrystaline silicon, CdTe and CIS solar modules, respective, for 23 cities in Serbia is given. Calculations performed by PVGIS program have shown that irrespectable of the type of PV solar plants, most electrical energy in Serbia can be generated by means of PV solar plants with CdTe solar cells. Some practical data and considerations given in this paper can be used by a customer or company keen to invest in the PV sector in Serbia. [Copyright &y& Elsevier]

This paper presents and analyzes Qatar's long-term solar resource potential to assess the power generation prospects of diverse solar plants in the country. Solar resource potential is obtained by applying kriging techniques to satellite-derived data to produce maps of monthly and yearly averages of global horizontal and direct normal irradiation. This analysis is based on eleven years of hourly satellite-derived solar radiation data calculated through a modified version of the Heliosat-3 model, where the satellite estimations have been improved and adapted to site using bias removal methods through a comparison with ground radiometric measurements. Solar resource data are then used in combination with local meteorological data as input to the System Advisor Model (SAM) in TMY3 format to simulate the solar plant operational prospects of various concentrating solar systems (CSP) and photovoltaic (PV) reference plants over eleven years. The ensuing simulation results show that parabolic troughs, molten salt tower plant with large thermal storage systems, and large grid-connected PV systems offer the best solutions in terms of interannual variability and long-term stability of the electricity produced. [ABSTRACT FROM AUTHOR]

In this paper, the potential of solar and wind energy-based distributed generation (DG) in Saudi Arabia is simultaneously analyzed with the aim of maximizing the utilization of available resources. It begins with an analysis of DG application potential for wind and solar energy resources in various regions of Saudi Arabia. The progress of DG applications in terms of research, planning, and exploitation of wind and solar energy resources is then presented. An assessment of the DG contribution to the energy sector of Saudi Arabia has been conducted and the barriers and challenges for the implementation of DG systems in the country are discussed with suggested measures to overcome the challenges. The main findings are that with the huge potential of wind and solar resources for DG applications the country has targeted 50 GW of wind and solar capacity by the year 2040. The Saudi government is expected to provide full support in the form of financial incentives for solar and wind energy projects in order to boost renewable energy development. [ABSTRACT FROM AUTHOR]

Usage of renewable and clean solar energy is expanding at a rapid pace. Applications of thermal energy storage (TES) facility in solar energy field enable dispatchability in generation of electricity and home space heating requirements. It helps mitigate the intermittence issue with an energy source like solar energy. TES also helps in smoothing out fluctuations in energy demand during different time periods of the day. In this paper, a summary of various solar thermal energy storage materials and thermal energy storage systems that are currently in use is presented. The properties of solar thermal energy storage materials are discussed and analyzed. The dynamic performances of solar thermal energy storage systems in recent investigations are also presented and summarized. [ABSTRACT FROM AUTHOR]

Greater penetrations of variable renewable generation on some electric grids have resulted in increased levels of curtailment in recent years. Studies of renewable energy grid integration have found that curtailment levels may grow as the penetration of wind and solar energy generation increases. This paper reviews international experience with curtailment of wind and solar energy on bulk power systems in recent years, with a focus on eleven countries in Europe, North America, and Asia. It examines levels of curtailment, the causes of curtailment, curtailment methods and use of market-based dispatch, as well as operational, institutional, and other changes that are being made to reduce renewable energy curtailment. [ABSTRACT FROM AUTHOR]

The contribution of solar photovoltaics (PV׳s) in generation of electric power is continually increasing. PV cells are commonly modelled as circuits. Finding appropriate circuit model parameters of PV cells is crucial for performance evaluation, control, efficiency computations and maximum power point tracking of solar PV systems. The problem of finding circuit model parameters of solar PV cells is referred to as “PV cell model parameter estimation problem,” and is highly attracted by researchers. In this paper, the existing research works on PV cell model parameter estimation problem are classified into three categories and the research works of those categories are reviewed. Based on the conducted review, some recommendations for future research are provided. [ABSTRACT FROM AUTHOR]

Abstract: The aims of this paper are to demonstrate a critical review of the multitude of progress in solar PV research and applications in Bangladesh since its inception in 1996 till 2010. Our studies show that Bangladesh has been experiencing an accelerated shift towards solar PV to meet the gap between demand and supply of electricity along with conventional electricity generation. Despite the present generation of electricity from solar PV is 15–20MW, both public and private sectors have started several solar PV projects to generate several hundred of MW by the upcoming years. This paper has also tried to identify the critical barriers for widespread dissemination of solar PV in Bangladesh and has discussed possible ways to overcome those barriers as well. [Copyright &y& Elsevier]

Abstract: Middle East and North Africa (MENA) countries present abundant solar potential, which to some extent has been exploited for electricity production. However, the largest part of this potential remains still unexploited. The scope of this paper is to present the best practices in exploiting solar energy in selected MENA countries. First the general structure of energy market related to Renewable Energy Sources (RES) for each analyzed country is presented. Then the exploitation of solar energy via PVs with special focus to the achievements in rural electrification, which could be used as a paradigm for other countries with similar problems, is displayed. MENA countries are promising for the wide application of concentrating solar plants (CSP), as recent research has shown, and some interesting applications in this area, also presented in this paper, have started being implemented. [Copyright &y& Elsevier]

Abstract: Due to the vast growth of development in the infrastructure and investment in energy, the electricity consumption in the GCC countries had increased at a fast rate; 12.4% from 2005 to 2009 (3.15%, annually). This rate is much larger than the world average, which is 2.2% for the same period, or USA (0.5%). In 2005, the average Watt per person in the GCC countries was 1149 which is much higher than the world average (297W per person) or the European Union (700W/person) – but less than USA (1460W/person). The GCC countries need to increase its electrical capacity by 60,000MW, which represents 80% of the current installed capacity, to meet demand in 2015. This means that there is a need to build 50 more gas fired power generator plant turbine (each rated 1400MW). The GCC countries have realized that depending on gas will not be the solution due to shortage of resource or environmental impact, particularly the GHG emissions. Therefore, they thought back of using renewable energy resources – after lifting it over in 1990s. They also thought of diversity in electricity production where nuclear energy comes to the picture. The power capacity in GCC countries is at around 75,000MW, a projected 9.5% growth in annual demand will require more electricity and energy projects; expected to invest USD 200 billion to 250 billion in between 14 and 20 energy projects by 2020. The paper lists the major renewable energy projects (mainly solar and wind) in each of the six GCC countries. The total capacity of these projects exceeds 600MW. Among these projects is the establishment of the first zero emission house (Green house) in the middle east (7kW solar, wind and fuel cell) constructed in Bapco residence town (Awali) in Bahrain and therefore, been highlighted more in this paper. Moreover, nearly all GCC countries are planning to construct PV plants with large capacity. Also, several projects in Building Integrated Photovoltaic and Building Integrated Wind Turbines are established in GCC countries. The projects made in the GCC countries allow researchers and investors to size the cost of kWh from thermal, PV and wind energy more precisely. For example, it was found that the cost of kWh from large grid connected solar thermal plant (20MW) – with cost of USD 72.5 million and energy – is US ¢ 12/kWh (assuming a life time of 40 years and a discount rate of 4%) while, the cost issue of kWh from PV Electricity (in the GCC countries) is ranging from US ¢ 27 (for ground mount) to US ¢ 35 (for roof mount) as it was deduced from two actually installed project PV in UAE – a GCC country member. Meanwhile, the cost of 1kWh from wind electricity in the GCC countries may be from US ¢10 (large turbine ≈2MW at 80m height with good wind speed) to US ¢ 15 (for large turbine ≈2MW at 80m height with modest wind speed) while the cost of kWh from grid connected Wind farm plant (20MW) – with a cost of USD 38.6 million and energy – is US ¢ 6.7/kWh to US ¢ 8.8/kWh, depending on the location of wind farm. This makes it very challengeable for investor, government (Feed-in-Tariff) and citizens because each citizen in GCC countries pays only (US cent 1 for each kWh, for consumption less than 3000kWh, or even nothing for citizens-like in Qatar). [Copyright &y& Elsevier]

Abstract: This paper analyses the renewable energy issues and electricity production in Middle East compared with Iran. Nevertheless, the use of renewable energy has started to be an interesting issue for people and also governments in Middle East, especially in Iran where all different types of renewable energy sources (RES) are available and also possible to implement for gaining required energy. There are many different kinds of renewable energy sources like geothermal, bio fuel, tidal and so on, but wind and solar energies are more available and accessible than other types in Middle Eastern countries. Nowadays, the rapidly increasing demand for electrical energy and the high restriction on pollution levels have led to an increasing interest in large-scale utilization of renewable energies across many countries in Middle East. This paper analyzes the electricity production in Middle East and also reviews different aspects of renewable energy issues in Iran. [Copyright &y& Elsevier]

Abstract: China is the largest developing country in the world. At present, more and more energy demand gives immense pressure to Chinese government. The inappropriate energy structure must be improved by Chinese government in order to achieve the sustainable development of economy and society. Development and application of renewable energy, such as wind energy, solar energy, biomass energy, etc., have been regarded by the government and the local people in the past 10 years, and more and more actual examples have been established, which are supported by government and plants in China. It is well known that there are abundant wind and solar resources in China. This paper presents the distribution zone and development and application practice status in China. However, a common drawback is existing in the stand-alone wind energy and solar energy generating power system, which is the unpredictable output electric power, and the output power depends on the unpredictable weather and climatic changes. Fortunately, the wind–solar hybrid generation system can partially overcome the problems. The conventional structure and key technology of stand-alone wind–solar hybrid generating system, the current status and outlook of wind–solar hybrid energy system are presented in the paper, for example, the city road lighting system, distributed generation, photovoltaic (PV) water pumping for irrigation, etc. At the end, the policies and laws of China central government and local governments are described, and the development barriers and recommendations are introduced. [Copyright &y& Elsevier]

With insolation levels ranging from 4 to 7 kW h/m 2 /day, the African continent receives a higher amount of solar energy on its surface than the rest of the world. Hence, investments in solar electricity generation projects in African countries have the potential to be economically attractive. This paper reviews the feasibility of off-grid solar photovoltaic (PV) systems in SSA, focusing on five major issues in the context of falling system costs: cost-effectiveness, affordability, financing, environmental impact, and poverty alleviation. Over time, solar PV system costs have fallen dramatically across the globe. This is also the case in SSA, yet the costs prevailing in SSA are much higher than the world average owing to political, financial, and technological risks. Solar PV power systems continue to be an extremely costly source of electricity for the vast majority of the rural poor in SSA. The levellized cost of energy for solar PV systems is high, at US$0.83 per kW h. With an annual rate of decrease of PV system costs of 4% and 7.67% it is estimated that it will take from 8.7 to 16.9 years for solar home systems for electricity generation to become competitive with conventional diesel generators. The cost of reducing greenhouse gas emissions through rural solar PV electrification is in the range 150–626 US$/tCO 2 , which is extremely high compared with the current price of traded CO 2 emission permits or current estimates of the social cost of carbon of approximately 39 US$/tCO 2 . Off-grid solar PV systems are not feasible financially or economically for rural households of SSA unless these technologies are subsidised from abroad. If the policy of a country is to encourage rural electrification, it should carry this out through a systematic expansion of either local or national grids rather than household-level solar PV systems. [ABSTRACT FROM AUTHOR]

Croatia has enormous renewable energy potential, particularly solar, but it is underperforming with regard to its use both for electricity production and heating. Paper focuses on the reasons therefor by analyzing the policy with regard to environment, subsidies, the role of international financial institutions, monopoly dimension of power utility companies, as well as social dimension. The author presents proposals for changing the status quo in order for Croatia to catch up with regard to securing reasonable solar and other renewable energy share in its energy supply. Apart from the state as regulator which has various instruments at its disposal to implement thoroughly the renewable energy use, local authorities should assume central role and responsibility for solarizing their territories and generating the energy locally from other renewable energy sources available on their territory. Municipal utility companies would thus add electricity production to their regular activities and could provide installation and maintenance services for individual energy generating systems within the territory of their competence. [ABSTRACT FROM AUTHOR]

Nigeria is faced with chronic electricity crisis that has resulted in the crippling of most sectors of the economy. It is estimated that only 40% of Nigerians are connected to the national grid and the connected population are exposed to frequent power outages. Nigeria׳s electricity grid is mainly powered by large hydropower and depleting hydrocarbon resources. Fossil-based electricity generation contributes not only to increase in carbon footprints, but also exposes the country to changes in price of petroleum resources and political instability from the oil producing region of the country. The country is blessed with abundant Renewable Energy (RE) resources that have not been fully exploited; these renewable resources have the potentials to change the status quo of power generation and consumption in the country. Availability of Renewable Energy Sources (RESs) in all parts of Nigeria has been demonstrated in several studies. However, there is presently no comprehensive review of RE development in Nigeria. This contribution aims to fill this gap by focusing on the current status and future prospects of RE in Nigeria as well as identifying the key challenges confronting full scale RE development in the country. We discussed the existing government policies and legislations, and proposed others that can help speed up the adoption of RE in Nigeria. We also compared RE development in Nigeria with four other sub-Sahara African countries. We hope that this paper will stimulate further research on how to address the energy crisis in Nigeria using the RESs. [ABSTRACT FROM AUTHOR]

In some countries, photovoltaic (PV) technology is at a stage of development at which it can compete with conventional electricity sources in terms of electricity generation costs, i.e., grid parity. A case in point is Germany, where the PV market has reached a mature stage, the policy support has scaled down and the diffusion rate of PV systems has declined. This development raises a fundamental question: what are the motives to adopt PV systems at grid parity? The point of departure for the relevant literature has been on the impact of policy support, adopters and, recently, local solar companies. However, less attention has been paid to the motivators for adoption at grid parity. This paper presents an in-depth analysis of the diffusion of PV systems, explaining the impact of policy measures, adopters and system suppliers. Anchored in an extensive and exploratory case study in Germany, we provide a context-specific explanation to the motivations to adopt PV systems at grid parity. [ABSTRACT FROM AUTHOR]

A significant number of Life Cycle Assessment (LCA) analyses of renewable energy technologies is available in the literature, even though there is a lack of consistent conclusions about the life cycle impacts of the different technologies. The reported results vary consistently, according to the size and the technology of the considered plant, thus limiting the utility of LCA to inform policy makers and constituting a barrier to the deployment of a full awareness on sustainable energies. This variability in LCA results, in fact, can generate confusion regarding the actual environmental consequences of implementing renewable technologies. The article reviews approximately 50 papers, related to more than 100 different case studies regarding solar energy (Concentrated Solar Power, Photovoltaic), wind power, hydropower, and geothermal power. A methodology for the harmonization of the results is presented. The detailed data collection and the results normalization and harmonization allowed a more reliable comparison of the various renewable technologies. For most of the considered environmental indicators, wind power technologies turn out to be the low end while geothermal and PV technologies the high end of the impact range where all the other technologies are positioned. [ABSTRACT FROM AUTHOR]

Geothermal, solar and wind are all clean, renewable energies with a huge amount of resources and a great potential of electricity generation. Geothermal energy had definitely dominated the renewable energy market in terms of the installed electricity power about 30 years ago. The unfortunate fact is that the total installed capacity of geothermal electricity has been eclipsed by solar and wind in recent years. In this paper, benefits of using renewable energy resources (RER) have been summarized and attempt has been made to explain the recent trends causing the shift from geothermal energy to solar and wind. Cost, payback time, size of power generation, construction time, resource capacity, characteristics of resource, and other factors were to compare geothermal, solar, and wind power generation systems. Furthermore, historical data from geothermal, solar, and wind industries were collected and analyzed at the global scale. The data from hydropower were also considered in the comparison. Finally, we proposed suggestions for the geothermal industry to catch up with solar and wind industries. [ABSTRACT FROM AUTHOR]

Population growth and economic development are leading to a continuous increase in energy demand in Egypt. At the same time conventional energy sources are diminishing amid growing global concern for the environment. These factors underline the importance of increasing the use of Renewable Energy sources. Egypt has enormous potential in Solar energy (CSP). There is sufficient proof of Egypt׳s potential for extracting energy from Concentrated Solar Power, especially power on demand generation. CSP represents a reliable and sustainable source of energy for Egypt with different outputs that can be used. In this paper, we present a road map strategy for the market introduction of CSP in Egypt, removing the main barriers for financing and starting market introduction in the peak load and the medium load segment of power supply. [ABSTRACT FROM AUTHOR]

India has tremendous potential for generating clean electricity through Renewable Energy Sources (RES) namely Hydro, Wind and Solar. This potential has been duly recognized and shows India׳s consciousness for reducing carbon footprint as a developing nation. Government of India with an aim to promote clean energy launched Jawaharlal Nehru National Solar Mission (JNNSM) on 11th January 2010, which is one of the eight missions under National Action Plan on Climate Change (NAPCC–2008). This mission visions to install 22,000 MW through grid connected and off grid power plants. Achieving an installed capacity of this quantum is a task full of challenges. To list the possible challenges and suggest a way forward, there is a need to study solar energy sector in India in the past, which has motivated the authors to discuss the evolution of solar energy in India since independence. Through this paper authors have tried to outline the journey of solar energy in India since 1950 till date and highlight the potential issues as barriers and challenges which could impact the ambitious mission taken up by Government of India. This study will help decision makers and various stakeholders to understand the current status, barriers and challenges for better planning and management in the field of solar energy. [ABSTRACT FROM AUTHOR]

Abstract: Global exploitation of renewable energy technologies is increasing rapidly due to the concern in global warming and dwindling supplies of fossil fuels. Most of the countries in the world are blessed with two or more renewable energy sources (RES) and hence have formulated policies to boost the utilization of RES for their electricity production. An assessment of renewable electricity scenario is essential for research and development related works in the field of renewable energy technologies in order to further develop the renewable energy industry. Recent developments in installation capacities, costs and reductions in electricity costs of major RES based electricity generation methods are discussed in this paper. It also includes the past growth and future expectations of renewable electricity production. The analysis shows that if the current developments in renewable industry continue, then a major share of global electricity production in the future could be supplied by renewable energy technologies. The analysis further shows that a significant amount of fuel cost and pollutants emission can be reduced by the increased use of RES based electrical power production technologies. [Copyright &y& Elsevier]

This paper provides a review of high-efficiency thermodynamic cycles and their applicability to concentrating solar power systems, primarily focusing on high-efficiency single and combined cycles. Novel approaches to power generation proposed in the literature are also highlighted. The review is followed by analyses of promising candidates, including regenerated He-Brayton, regenerated CO2-Brayton, CO2 recompression Brayton, steam Rankine, and CO2–ORC combined cycle. Steam Rankine is shown to offer higher thermal efficiencies at temperatures up to about 600°C but requires a change in materials for components above this temperature. Above this temperature, CO2 recompression Brayton cycles are shown to have very high thermal efficiency, potentially even exceeding 60% at 30MPa maximum pressure and above 1000°C maximum temperature with wet cooling. An estimate of a combined receiver and power cycle operating temperature is provided for the cycles considered and compared to the traditional approach of optimization based on the Carnot efficiency. It is shown that the traditional approach to optimizing the receiver and turbine inlet temperatures based on Carnot is generally not sufficient, leading to an optimum temperature shift of more than 100°C from the Carnot case under various conditions. [ABSTRACT FROM AUTHOR]

Abstract: The photovoltaics industry has made steady progress over the past 40 years toward increasing solar cell and module efficiencies while incrementally lowering the initial installed cost of photovoltaic systems. These two factors dominate in lowering the cost of solar electric energy (in ¢/(kW-h)) as it approaches parity in cost with electric energy produced conventionally using coal, nuclear, or natural gas. An interesting question regards whether there is a relationship that describes the evolution of photovoltaics Levelized Cost of Energy (LCOE) similar to Moore's Law characterization of microelectronics evolution of transistor size and density. With some caveats, we believe a similar PV relationship can be defined; the purpose of this paper is to propose and discuss a basis for this relationship. To achieve parity the installed cost of PV systems needs to be reduced by 50% from approximately $600/m2 to $300/m2 with a concurrent increase in c-Si module efficiency to 24% AM1.5. The trajectories in time needed to drive a technology roadmap for lowering the installed cost and for increasing the module efficiency to achieve parity are discussed. Also, a new methodology for calculating LCOE for PV systems is proposed and discussed in Appendix. [Copyright &y& Elsevier]

Abstract: Perhaps the greatest obstacle to large-scale solar energy generation is the intermittent nature of solar energy and the associated costly storage. This paper presents a method to optimize combinations of selected worldwide regions in different time zones with the surprising capability of providing sufficient electricity generation to overcome intermittency or reduce it to such an extent that substantially less storage and generation capacity are needed. The recent sharp drop in the cost of photovoltaic (PV) generation capability accompanied by worldwide increased investment in PV plants suggests a new economic base for cooperative efforts to sequentially combine day time insolation. The approach presented here optimizes two aspects, first, the selection of sites across large geographic areas, and second, the size and relative proportion of generation and storage capacity at each site. Our approach converts 20 years of daily insolation data by NASA Solar Sizer to hourly scale. The hourly data are used to assess and compare supranational distributed solar networks in different parts of the globe that have recently been proposed, and to subsequently optimize their generation capacity and storage. We show that linking regions in different time zones and on the two hemispheres can fully eliminate intermittency without the need for fuel and renewable energy other than solar. [Copyright &y& Elsevier]

Present day India has tremendous energy requirements, and with each day it is becoming more difficult to meet those needs through conventional power sources. The never-ending demand of population which is growing exponentially has become very tough to fulfill. To enhance its energy security, mitigate carbon emissions and augment its economic development, it becomes an urgent need to implement innovative policies and mechanisms for the adoption of green and clean energy. India because of its demographics has good solar energy potential. This study aims to examine the solar power implementations in thermal power plants situated all across India. This paper contributes to the literature on solar power by identification of barriers for the adoption of solar power in thermal plants. Still, there is some lack of study about solar power implementations in different areas. In this paper, investigating efforts have been made to examine the solar power implementations in thermal power plants within the Indian context by identifying key barriers. In this study, Interpretative Structural Modeling (ISM) has been adopted to find the contextual relationships among key barriers and Matriced'Impacts Croises- Multiplication Applique' an Classment (MICMAC) analysis has been carried out for validation of the model. Requirement of gigantic investment, longer recovery period, safety implications, environmental implications, and societal concerns emerge at the top level in ISM structure. Lack of adequate government policies and lack of political leadership appears at the bottom of a structured model and these emerged as the most influential barriers. This research also suggested how to mitigate the key barriers by the installation of solar power in electricity generation utilities. • Identify and evaluate nineteen barriers which influence the development of solar power in Indian thermal power sector. • Establish ISM hierarchy structure to show the contextual relationships among the barriers. • MICMAC technique is conceded for validation of the established ISM model. • Suggestions are proposed to mitigate the key barriers for the development of solar power in electricity generation utilities. [ABSTRACT FROM AUTHOR]

Abstract: The development in solar PV technology is growing very fast in recent years due to technological improvement, cost reductions in materials and government support for renewable energy based electricity production. Photovoltaic is playing an important role to utilize solar energy for electricity production worldwide. At present, the PV market is growing rapidly with worldwide around 23.5GW in 2010 and also growing at an annual rate of 35–40%, which makes photovoltaic as one of the fastest growing industries. The efficiency of solar cell is one of the important parameter in order to establish this technology in the market. Presently, extensive research work is going for efficiency improvement of solar cells for commercial use. The efficiency of monocrystalline silicon solar cell has showed very good improvement year by year. It starts with only 15% in 1950s and then increase to 17% in 1970s and continuously increase up to 28% nowadays. The growth in solar photovoltaic technologies including worldwide status, materials for solar cells, efficiency, factor affecting the performance of PV module, overview on cost analysis of PV and its environmental impact are reviewed in this paper. [Copyright &y& Elsevier]

Abstract: The growing demand for electrical power and the limited capital invested to provide this power is forcing countries like Brazil to search for new alternatives for electrical power generation. The purpose of this paper is to present a technical and economic study on a 15kW solar plant installed in an isolated community, highlighting the importance of the need for financial subsidy from the government. It evaluates the importance of parameters such as the annual interest rate, specific investment, the marginal cost of expanding the electrical power supply and the government subsidy on amortization time of capital invested. [Copyright &y& Elsevier]

Abstract: Due to the rapid economic and social development, China''s power generation mix is dominated by thermal power, resulting in rapid growth of CO2 emission during the past decades. Suffering from the two severe problems of energy crisis and global warming, power generation mix should be optimized by installing more new energy during China''s 12th and 13th Five-Year Plan periods. In order to realize the massive utilization of new energy and realize emission reduction targets in the future, it is of great significance for China to promote development of large new energy bases such as hydropower, wind power, solar power, nuclear power etc. In this paper we provide an overall review of China''s large new energy bases development with a detailed presentation of construction status and future plan, analyze the policy problems and technology barriers hindering the development of new energy bases in China, which will provide sound reference for policy makers. [Copyright &y& Elsevier]

Abstract: This paper presents an overview of the technical and economic aspects, as well as the market evolution of the Organic Rankine Cycle (ORC). This is an unconventional but very promising technology for the conversion of thermal energy, at low and medium temperatures, into electrical and/or mechanical energy on a small scale. As it makes a greater and/or more intensive use of its energy source, this technology could facilitate an electricity supply to unconnected areas, the self-production of energy, the desalination of seawater for human consumption, or even to increase the energy efficiency in the industrial sector respecting the environment. A look at the scientific publications on this topic shows an open research line, namely the selection of a suitable working fluid for these systems, since there is as yet none that provides all aspects that must be taken into account in ORCs. Furthermore, a description and an analysis of the applications of the proposed technology is carried out, specifying the main providers, which at the present time is limited mainly to the range 0.2–2MWe with a cost of around 1 and 4×103 €/kWe. Lower powers are in pre-commercial status. [Copyright &y& Elsevier]

Abstract: Serbian government has recently introduced the system of feed-in tariffs for electricity generated from renewable sources. The proposed feed-in tariff for photovoltaic electricity is set to 0.23€/kWh paid for 12 years, with the PV electricity produced after the first 12 years being sold at the grid electricity market price for the rest of the plant lifetime. Although such FIT could have been justified by the small, average retail grid electricity price of just 0.054€/kWh for Serbian households, the investment appraisal of a real case of 2.82kWp PV power plant in two Serbian cities of Zlatibor and Negotin, clearly illustrates that the proposed FIT framework is not sufficient to attract investments into PV in Serbia. In the second part of the paper, we have analyzed alternative, more reasonable feed-in tarrif frameworks, with the goal of selecting those able to sustain the PV adoption and diffusion in Serbia. [Copyright &y& Elsevier]