Financial analysis of utility scale photovoltaic plants with battery energy storage

Battery energy storage is a flexible and responsive form of storing electrical energy from Renewable generation. The need for energy storage mainly stems from the intermittent nature of solar and wind energy sources. System integrators are investigating ways to design plants that can provide more stable output power without compromising the financial performance that is vital for investors. Network operators on the other side set stringent requirements for the commissioning of new generation, including preferential terms for energy providers with a well-defined generation profile. The aim of this work is to highlight the market and technology drivers that impact the feasibility of battery energy storage in a Utility-scale solar PV project. A simulation tool combines a battery cycling and lifetime model with a solar generation profile and electricity market prices. The business cases of the present market conditions and a projected future scenario are analyzed.     

Thermal modeling of a combined system of photovoltaic thermal (PV/T) solar water heater

In this paper, an integrated combined system of a photovoltaic (glass–glass) thermal (PV/T) solar water heater of capacity 200 l has been designed and tested in outdoor condition for composite climate of New Delhi. An analytical expression for characteristic equation for photovoltaic thermal (PV/T) flat plate collector has been derived for different condition as a function of design and climatic parameters. The testing of collector and system were carried out during February–April, 2007. It is observed that the photovoltaic thermal (PV/T) flat plate collector partially covered with PV module gives better thermal and average cell efficiency which is in accordance with the results reported by earlier researchers.     

Optimal operation of an all-in-one EV station with photovoltaic system including charging,battery swapping and hydrogen refueling

The issue of electrification of transportation is discussed due to the possibility of depletion of conventional resources in the near future and environmental problems caused by carbon emissions. For this purpose, different options have been proposed for the electrification of electric vehicles (EVs). Each potential EV user can choose a different EV type according to his desire, so different EV types can be seen in the environment. However, one of the most important reasons why the prevalence of EVs has not increased is the scarcity of EV charging, swapping, or refueling stations. In this respect, there is a need for an all-in-one EV station (AiOEVS) that can serve all types of EVs around and that all users know to be able to meet their energy needs easily and in line with their wishes. In this study, the economically optimum energy management model via mixed-integer linear programming (MILP) approach of an AiOEVS including a photovoltaic (PV) system as well electrolyzer and consisting of three different parts (charging for plug-in EVs, swapping for swappable EVs, and refueling for hydrogen fuel-cell EVs (HFCEVs)) is proposed. Besides, energy is purchased from the grid with time-of-use electricity prices. The proposed optimum operating framework is beneficial for each party. Furthermore, the hydrogen tank, swappable batteries, and long-parking plug-in EVs provide operational flexibility. The AiOEVS owner obtains a net profit of 33.12% at the end of the day. Furthermore, when the capacity of the PV is doubled or tripled, the gain increases by 11.69% or 23.41%, respectively.     

Enhanced control strategies for a hybrid battery/photovoltaic system using FGS-PID in grid-connected mode

This paper suggests improved control strategies using Fuzzy Gain Scheduling of Proportional-Integral-Derivative (FGS-PID) controller for a hybrid Photovoltaic (PV) and Battery Energy Storage (BES) system under different weather conditions. The proposed scheme is implemented using a two-level control system structure, combining the benefits of the PID as well as the fuzzy logic controller (FLC) for maximum power point tracking (MPPT). Ziegler-Nichols tuning method is also employed to select the initial values of PID gains. Within the period of steady-states and transients, FGS-PID adopts the gains to ensure the stability of the control scheme. It also damps out transient fluctuations and reduces settling time. Also, BES could be employed to provide a stable and reliable power from the output of PV sources to loads. It can enhance the performance of the entire power system during the grid-connected mode. The simulation results under Matlab/Simulink show that the suggested control strategies are robustness, fast transient response and proper steady-state performance in the grid-connected mode in comparison other presented methods.     

Controlling of grid connected photovoltaic lighting system with fuzzy logic

In this study, DC electrical energy produced by photovoltaic panels is converted to AC electrical energy and an indoor area is illuminated using this energy. System is controlled by fuzzy logic algorithm controller designed with 16 rules. Energy is supplied from accumulator which is charged by photovoltaic panels if its energy would be sufficient otherwise it is supplied from grid. During the 1-week usage period at the semester time, 1.968 kWh energy is used from grid but designed system used 0.542 kWh energy from photovoltaic panels at the experiments. Energy saving is determined by calculations and measurements for one education year period (9 months) 70.848 kWh.     

The potential for integration of hydrogen for complete energy self-sufficiency in residential buildings with photovoltaic and battery storage systems

This paper presents an analysis of energy production in a pilot building located in Slovenia, which is a typical residential house with an installed photovoltaic (PV) system and pilot battery storage system. Energy management system gathers data from smart meters every 15 min. As the pilot building location is in central Europe, complete energy self-sufficiency cannot be provided. The most problematic period of energy production with photovoltaic systems is winter. Solar radiation during the winter is much lower than in the summer and sometimes snow covers photovoltaic panels and disables energy production. Energy production and energy consumption are analyzed for one year. This study shows that complete self-sufficiency can be achieved by supplementing photovoltaic systems with hydrogen fuel cells. The amount of hydrogen, which would suffice for complete self-sufficiency for the whole period, is calculated according to the analyzed data. A synergy between photovoltaic system and hydrogen fuel cells is a step forward to complete self-sufficiency with renewable energy sources. The share of self-sufficiency of a hybrid PV fuel cell system would be 62.13%, meaning that there is no possibility for complete self-sufficiency from the pilot system. The shortage of hydrogen is 144.24 kg for one year and for achieving complete energy self-sufficiency, PV system should be bigger. A hybrid system with photovoltaic system, battery storage system and hydrogen fuel cells can be a solution for complete self-sufficiency. From an economic point of view, such systems are accessible for commercial use. The initial investment is relatively high, because of the high cost of the hydrogen storage tank.     

Modeling,control and power management of hybrid photovoltaic fuel cells with battery bank supplying electric vehicle

In this paper, modeling, control and power management (PM) of hybrid Photovoltaic Fuel cell/Battery bank system supplying electric vehicle is presented. The HPS is used to produce energy without interruption. It consists of a photovoltaic generator (PV), a proton exchange membrane fuel cell (PEMFC), and a battery bank supplying an electric vehicle of 3 kW. In our work, PV and PEMFC systems work in parallel via DC/DC converter and the battery bank is used to store the excess of energy. The mathematical model topology and it power management of HPS with battery bank system supplying electric vehicle (EV) are the significant contribution of this paper. Obtained results under Matlab/Simulink and some experimental ones are presented and discussed.     

Output energy of a photovoltaic module mounted on a single-axis tracking system

In this study, the electric energy from a photovoltaic module was calculated theoretically at different azimuths and tilt angles in Taiwan. The gain of the module mounted on a single-axis tracking panel relative to a traditional fixed panel was analyzed. To simulate different operation environments, both types of radiation will be considered in addition to observed radiation, i.e. the extraterrestrial radiation and the global radiation predicted by an empirical model. The results show that the optimal tilt angle obtained from the observed data is flatter than those from other two radiation types and becomes flatter while the panel deviates from due south. The yearly gains obtained from the extraterrestrial, predicted and observed radiations are 51.4%, 28.5% and 18.7%, respectively, if a single-axis tracked panel is installed with the yearly optimal tilt angle; the similar gains are 45.3%, 25.9% and 17.5%, respectively, while the panel is adjusted to its monthly optimal angle each month. The amount of yearly energy in due west (or east) is less than its maximum in due south by about 11%, 10% and 5% for the extraterrestrial, predicted and observed radiation respectively. The yearly conversion efficiency of a fixed module is 10.2%, 9.2% and 8.3% for the extraterrestrial, predicted and observed radiation, respectively.     

Computer modeling and experimental validation of a building-integrated photovoltaic and water heating system

A dynamic simulation model of a building-integrated photovoltaic and water heating system is introduced in this paper. The numerical model was developed based on the finite difference control volume approach. The integrated use of energy balance and fluid flow analysis allows the prediction of the system dynamic behavior under external excitations such as changes in weather, water consumption and make-up conditions. The validity of the modeling approach was demonstrated by comparing its predicted operating temperature changes and system daily efficiencies with the measured data acquired from an experimental rig at the City University of Hong Kong. The predictions from the model show good compliance with the experimental measurements.     

Optimization of a photovoltaic pumping system based on the optimal control theory

This paper suggests how an optimal operation of a photovoltaic pumping system based on an induction motor driving a centrifugal pump can be realized. The optimization problem consists in maximizing the daily pumped water quantity via the optimization of the motor efficiency for every operation point. The proposed structure allows at the same time the minimization the machine losses, the field oriented control and the maximum power tracking of the photovoltaic array. This will be attained based on multi-input and multi-output optimal regulator theory. The effectiveness of the proposed algorithm is described by simulation and the obtained results are compared to those of a system working with a constant air gap flux.     

A photovoltaic/thermal system with a combination of a booster diffuse reflector and vacuum tube for generation of electricity and hot water production

Using water as a coolant to reduce the temperature of solar cells is one of the best methods for improving the efficiency of a photovoltaic/thermal system. However the heat absorbed from the solar cell panel is not enough for providing domestic hot water. In this article, a new architecture of photovoltaic/thermal system is proposed and investigated. A silicon monocrystalline photovoltaic module is used with appropriate reflectors in order to increase insolation in conjunction with a closed loop cooling facility to efficiently extract the panel's heat. The absorbed heat from the photovoltaic/thermal panel, is used to preheat the water flow before entering four vacuum tube solar water heaters placed on both sides of the photovoltaic/thermal panel. Performance evaluation of this system in comparison to a similar bare photovoltaic panel, showed a significant increase in the system's electrical and thermal energy output.     

Modeling of hybrid photovoltaic/wind/fuel cells power system

In this paper, identification and modeling of a hybrid photovoltaic/wind/fuel cells power system is presented. This system comprises also a battery storage supplying a load via an inverter. The identification of each subsystem has been made and then the proposed system is modeled and simulated under Matlab/Simulink Package. The power control of the hybrid system is introduced by using LabVIEW Software. The mathematical model topology and its power management of the global system with battery bank system are significant contributions of our work. The proposed control strategy has been experimentally implanted and practical results are compared to those obtained by simulation under the same metrological conditions, showing the effectiveness of the proposed hybrid system.     

Small-scale irrigation with photovoltaic water pumping system in Sahara regions

Several photovoltaic applications, specially the water pumping systems, are installed to contribute in the socio–economic development in Algerian Sahara. About sixty pumps are installed in remote regions to supply water for drinking and irrigation. The centrifugal pumps present the state-of-the-art for most applications. This paper presents the electrical and hydraulic performance of a surface centrifugal pump versus total water heads and versus a size of PV array. Also the area irrigated by this solar surface pump is calculated under Sahara climate conditions for four crops, namely wheat, potatoes, tomatoes and sunflowers. These were selected to meet with food standards of the sites. Two application sites were chosen to test the developed model. The first is Bechar station and the second is Tamanrasset station. In both, the recorded solar radiation data were used. The results, which are illustrated by tables and curves, are analysed. The analysis of the performance concluded that this surface pump is suitable for installation in the Sahara regions with low water head.     

Thermographic analysis of a building integrated photovoltaic system

A residential-scale building integrated photovoltaic (BiPV) cogeneration system has been thermographically investigated. The results are useful in calibrating the numerical models created to predict the system's operational temperatures. The combined heat and power system is based on existing BiPV roofing technology with the addition of a modular heat recovery unit. The convection of the air behind the panels will serve both to cool the photovoltaic panels and provide a heat source for the residence. The analysis allows for the interpretation of the surface emissivities and operating temperatures, as well as qualitative graphic analysis of temperature gradients.     

Procedure for optimal design of hydrogen production plants with reserve storage and a stand-alone photovoltaic power system

A procedure for sizing an electrolytic hydrogen production plant powered by a stand-alone photovoltaic system is described in this study. Our fundamental proposal is to compensate the loss of load probability of the photovoltaic system, by means of a hydrogen complementary storage. We compute the necessary hydrogen volume of that reserve storage. Using the isoreliability map of curves that characterizes a given location, we determine the size of the photovoltaic system that would be needed to generate a predetermined flow of hydrogen. Finally, we share information on our own experience relating to the design of the experimental installation at Villafría, located in the city of Burgos, Spain.     

Exergy analysis of integrated photovoltaic thermal solar water heater under constant flow rate and constant collection temperature modes

In this communication, an analytical expression for the water temperature of an integrated photovoltaic thermal solar (IPVTS) water heater under constant flow rate hot water withdrawal has been obtained. Analysis is based on basic energy balance for hybrid flat plate collector and storage tank, respectively, in the terms of design and climatic parameters. Further, an analysis has also been extended for hot water withdrawal at constant collection temperature. Numerical computations have been carried out for the design and climatic parameters of the system used by Huang et al. [Huang BJ, Lin TH, Hung WC, Sun FS. Performance evaluation of solar photovoltaic/thermal systems. Sol Energy 2001; 70(5): 443–8]. It is observed that the daily overall thermal efficiency of IPVTS system increases with increase constant flow rate and decrease with increase of constant collection temperature. The exergy analysis of IPVTS system has also been carried out. It is further to be noted that the overall exergy and thermal efficiency of an integrated photovoltaic thermal solar system (IPVTS) is maximum at the hot water withdrawal flow rate of 0.006 kg/s. The hourly net electrical power available from the system has also been evaluated.     

Dynamic modeling of a photovoltaic hydrogen fuel cell hybrid system

The objective of this paper is to mathematically model a stand-alone renewable power system, referred to as “Photovoltaic–Fuel Cell (PVFC) hybrid system”, which maximizes the use of a renewable energy source. It comprises a photovoltaic generator (PV), a water electrolyzer, a hydrogen tank, and a proton exchange membrane (PEM) fuel cell generator. A multi-domain simulation platform Simplorer is employed to model the PVFC hybrid systems. Electrical power from the PV generator meets the user loads when there is sufficient solar radiation. The excess power from the PV generator is then used for water electrolysis to produce hydrogen. The fuel cell generator works as a backup generator to supplement the load demands when the PV energy is deficient during a period of low solar radiation, which keeps the system's reliability at the same level as for the conventional system. Case studies using the present model have shown that the present hybrid system has successfully tracked the daily power consumption in a typical family. It also verifies the effectiveness of the proposed management approach for operation of a stand-alone hybrid system, which is essential for determining a control strategy to ensure efficient and reliable operation of each part of the hybrid system. The present model scheme can be helpful in the design and performance analysis of a complex hybrid-power system prior to practical realization.     

Cost and surface optimization of a remote photovoltaic system for two kinds of panels’ technologies

Stand alone photovoltaic (PV) systems comprise one of the promising electrification solutions to cover the demand of remote consumers, especially when it is coupled with a storage solution that would both increase the productivity of power plants and reduce the areas dedicated to energy production.This short communication presents a multi-objective design of a remote PV system coupled to battery and hydrogen storages systems simultaneously minimizing the total levelized cost and the occupied area, while fulfilling a constraint of consumer satisfaction.For this task, a multi-objective code based on particle swarm optimization has been used to find the best combination of different energy devices. Both short and mid terms based on forecasts assumptions have been investigated.An application for the site of La Nouvelle in the French overseas island of La Réunion is proposed. It points up a strong cost advantage by using Heterojunction with Intrinsic Thin layer (HIT) rather than crystalline silicon (c-Si) cells for the short term. However, the discrimination between these two PV cell technologies is less obvious for the mid term: a strong constraint on the occupied area will promote HIT, whereas a strong constraint on the cost will promote c-Si.     

Thermal performance analysis of a direct-expansion solar-assisted heat pump water heater

A direct-expansion solar-assisted heat pump water heater (DX-SAHPWH) is described, which can supply hot water for domestic use during the whole year. The system mainly employs a bare flat-plate collector/evaporator with a surface area of 4.2 m², an electrical rotary-type hermetic compressor, a hot water tank with the volume of 150 L and a thermostatic expansion valve. R-22 is used as working fluid in the system. A simulation model based on lumped and distributed parameter approach is developed to predict the thermal performance of the system. Given the structure parameters, meteorological parameters, time step and final water temperature, the numerical model can output operational parameters, such as heat capacity, system COP and collector efficiency. Comparisons between the simulation results and the experimental measurements show that the model is able to give satisfactory predictions. The effect of various parameters, including solar radiation, ambient temperature, wind speed and compressor speed, has been analyzed on the thermal performance of the system.     

Optimal operation of a photovoltaic generation-powered hydrogen production system at a hydrogen refueling station

As the popularity of fuel cell vehicles continues to rise in the global market, production and supply of low-carbon hydrogen are important to mitigate CO₂ emissions. We propose a design for a hydrogen refueling station with a proton exchange membrane electrolyzer (PEM-EL)-based electrolysis system (EL-System) and photovoltaic generation (PV) to supply low-carbon hydrogen. Hydrogen is produced by the EL-System using electricity from PV and the power grid. The system was formulated as a mixed integer linear programming (MILP) model to allow analysis of optimal operational strategies. Case studies with different objective functions, CO₂ emission targets, and capacity utilization of the EL-System were evaluated. Efficiency characteristics of the EL-System were obtained through measurements. The optimized operational strategies were evaluated with reference to three evaluation indices: CO₂ emissions, capacity utilization, and operational cost of the system. The results were as follows: 1) Regardless of the objective function, the EL-System generally operated in highest efficiency state, and optimal operation depended on the efficiency characteristics of the EL-System; 2) mitigation of CO₂ emissions and increase in capacity utilization of the EL-System required trade-offs; and 3) increased capacity utilization of the EL-System showed two opposing effects on hydrogen retail price.