Effect of urban climate on building integrated photovoltaics performance

It is generally recognized that BIPV (building integrated photovoltaics) has the potential to become a major source of renewable energy in the urban environment. The actual output of a PV module in the field is a function of orientation, total irradiance, spectral irradiance, wind speed, air temperature, soiling and various system-related losses. In urban areas, the attenuation of solar radiation due to air pollution is obvious, and the solar spectral content subsequently changes. The urban air temperature is higher than that in the surrounding countryside, and the wind speed in urban areas is usually less than that in rural areas. Three different models of PV power are used to investigate the effect of urban climate on PV performance. The results show that the dimming of solar radiation in the urban environment is the main reason for the decrease of PV module output using the climatic data of urban and rural sites in Mexico City for year 2003. The urban PV conversion efficiency is higher than that of the rural PV system because the PV module temperature in the urban areas is slightly lower than that in the rural areas in the case. The DC power output of PV seems to be underestimated if the spectral response of PV in the urban environment is not taken into account based on the urban hourly meteorological data of Sao Paulo for year 2004. © 2006 Elsevier Ltd. All rights reserved.

Calculation of the hourly and daily radiation incident on three step tracking planes

Mathematical formulas for estimating the hourly and daily radiation incident on planes of azimuth three step tracking and hour angle three step tracking have been derived in this paper. Based on the hourly solar radiation data of an average day in each month at Er-Lian-Hao-Te city, the hourly and monthly radiation received by planes of these two kinds of tracking have been calculated. The results show that in this district, one axis azimuth three step tracking and hour angle three step tracking could, respectively, obtain 66.5% and 63.3% higher radiation than that on the horizontal surface all year. Moreover, a two axis azimuth three step tracking plane could receive 72% more radiation than the horizontal surface. (C) 2002 Elsevier Science Ltd. All rights reserved.

Sistemas fotovoltaicos este-oeste con capacidad de almacenamiento en la industria

El objetivo de este proyecto fin de carrera es ajustar el perfil generado por un sistema fotovoltaico con orientación este-oeste que dispone de una batería al perfil de demanda de distintas industrias en Alemania. Se ha puesto especial énfasis a los siguientes paquetes de trabajo: • Comparación de la eficiencia de un sistema fotovoltaico este-oeste frente a los resultados obtenidos con la típica orientación sur • Simulación de una instalación fotovoltaica este-oeste con una batería en una industria, basada en el software MATLAB / Simulink • Optimización económica. Los resultados obtenidos muestran que nunca es económico instalar un campo fotovoltaico este-oeste en vez de una instalación con orientación sur, en caso de que la única ventaja esperada sea el ensanche de la curva de generación de potencia.

Economics of Hybrid Photovoltaic Power Plants

The global power supply stability is faced to several severe and fundamental threats, in particular steadily increasing power demand, diminishing and degrading fossil and nuclear energy resources, very harmful greenhouse gas emissions, significant energy injustice and a structurally misbalanced ecological footprint. Photovoltaic (PV) power systems are analysed in various aspects focusing on economic and technical considerations of supplemental and substitutional power supply to the constraint conventional power system. To infer the most relevant system approach for PV power plants several solar resources available for PV systems are compared. By combining the different solar resources and respective economics, two major PV systems are identified to be very competitive in almost all regions in the world. The experience curve concept is used as a key technique for the development of scenario assumptions on economic projections for the decade of the 2010s. Main drivers for cost reductions in PV systems are learning and production growth rate, thus several relevant aspects are discussed such as research and development investments, technical PV market potential, different PV technologies and the energetic sustainability of PV. Three major market segments for PV systems are identified: off-grid PV solutions, decentralised small scale on-grid PV systems (several kWp) and large scale PV power plants (tens of MWp). Mainly by application of ‘grid-parity’ and ‘fuel-parity’ concepts per country, local market and conventional power plant basis, the global economic market potential for all major PV system segments is derived. PV power plant hybridization potential of all relevant power technologies and the global power plant structure are analyzed regarding technical, economical and geographical feasibility. Key success criteria for hybrid PV power plants are discussed and comprehensively analysed for all adequate power plant technologies, i.e. oil, gas and coal fired power plants, wind power, solar thermal power (STEG) and hydro power plants. For the 2010s, detailed global demand curves are derived for hybrid PV-Fossil power plants on a per power plant, per country and per fuel type basis. The fundamental technical and economic potentials for hybrid PV-STEG, hybrid PV-Wind and hybrid PV-Hydro power plants are considered. The global resource availability for PV and wind power plants is excellent, thus knowing the competitive or complementary characteristic of hybrid PV-Wind power plants on a local basis is identified as being of utmost relevance. The complementarity of hybrid PV-Wind power plants is confirmed. As a result of that almost no reduction of the global economic PV market potential need to be expected and more complex power system designs on basis of hybrid PV-Wind power plants are feasible. The final target of implementing renewable power technologies into the global power system is a nearly 100% renewable power supply. Besides balancing facilities, storage options are needed, in particular for seasonal power storage. Renewable power methane (RPM) offers respective options. A comprehensive global and local analysis is performed for analysing a hybrid PV-Wind-RPM combined cycle gas turbine power system. Such a power system design might be competitive and could offer solutions for nearly all current energy system constraints including the heating and transportation sector and even the chemical industry. Summing up, hybrid PV power plants become very attractive and PV power systems will very likely evolve together with wind power to the major and final source of energy for mankind.

Rapport från 20th European Photovoltaic Solar Energy Conference and Exhibition : Barcelona 6-10 juni 2005

På uppdrag av STEM bevakade Eva Lindberg från Centrum för solenergi-forskning, SERC, Högskolan Dalarna, 20th European Photovoltaic Solar Energy Conference and Exhibition, Barcelona, 6-10 juni 2005. Ca 1700 personer fanns på deltagarlistan. På grund av konferensen omfattning kan endast ett litet urval av föredrag och utställare kommenteras i rapporten. Konferensprogrammet var indelat på följande områden:1. Grundläggande fakta, nya komponenter och material2. Kristallina kiselsolceller and materialteknologi3. Amorft och mikrokristallint kisel4. CIS, CdTe och andra (II-VI) ternära tunnfilmsceller5. PV-moduler och komponenter i PV-system6. PV-system i nätanslutna applikationer7. Globala aspekter på PV-solelektricitet8. PV-industrins resultatFoU om kristallina solceller dominerade stort, sedan tunnfilmsceller av främst amorft kisel. Intressant var att återvinning är föremål för FoU; dels återvinning av kiselsolceller när panelen tjänat ut; dels återvinning av Cu, Cd, Se och Te när tunnfilmscellerna tas ur bruk.237 företag fanns representerade i utställningen, varav 20 från Kina. Tyskland dominerade stort. Utställningen teman var följande: 1) Tillverkare av kiselplattor, solceller, PV-moduler, koncentratorer, solföljare (se bild nedan) 2) Tillverkare och återförsäljare av utrustning och material 3) Integrering och distribution av system 4) Mätningar och kontrollteknologi 5) Forskning och laboratorier 6) Service, teknik, konsulting 7) Myndigheter och föreningar 8) Media och förlag 9) Tillverkare av inverterare 10) Övrigt.

Use of Photovoltaic on an E-bike? : A Feasibility Study

In recent years the number of bicycles with e-motors has been increased steadily. Within the pedelec – bikes where an e-motor supports the pedaling – a special group of transportation bikes has developed. These bikes have storage boxes in addition to the basic parts of a bike. Due to the space available on top of those boxes it is possible to install a PV system to generate electricity which could be used to recharge the battery of the pedelec. Such a system would lead to grid independent charging of the battery and to the possibility of an increased range of motor support. The feasibility of such a PV system is investigated for a three wheeled pedelec delivered by the company BABBOE NORDIC.The measured data of the electricity generation of this mobile system is compared to the possible electricity generation of a stationary system.To measure the consumption of the pedelec different tracks are covered, and the energy which is necessary to recharge the bike battery is measured using an energy logger. This recharge energy is used as an indirect measure of the electricity consumption. A PV prototype system is installed on the bike. It is a simple PV stand alone system consisting of PV panel, charge controller with MPP tracker and a solar battery. This system has the task to generate as much electricity as possible. The produced PV current and voltage aremeasured and documented using a data logger. Afterwards the average PV power is calculated. To compare the produced electricity of the on-bike system to that of a stationary system, the irradiance on the latter is measured simultaneously. Due to partial shadings on the on-bike PV panel, which are caused by the driver and some other bike parts, the average power output during riding the bike is very low. It is too low to support the motor directly. In case of a similar installation as the PV prototype system and the intention always to park the bike on a sunny spot an on-bike system could generate electricity to at least partly recharge a bike battery during one day. The stationary PV system using the same PV panel could have produced between 1.25 and 8.1 times as much as the on-bike PV system. Even though the investigation is done for a very specific case it can be concluded that anon-bike PV system, using similar components as in the investigation, is not feasible to recharge the battery of a pedelec in an appropriate manner. The biggest barrier is that partial shadings on the PV panel, which can be hardly avoided during operation and parking, result in a significant reduction of generated electricity. Also the installation of the on-bike PV system would lead to increased weight of the whole bike and the need for space which is reducing the storage capacity. To use solar energy for recharging a bike battery an indirect way is giving better results. In this case a stationary PV stand alone system is used which is located in a sunny spot without shadings and adjusted to use the maximum available solar energy. The battery of the bike is charged using the corresponding charger and an inverter which provides AC power using the captured solar energy.

Lessons from the greenest city

In 2007, the City of Växjö in Sweden was voted the greenest city in Europe. Over an 18-year period, greenhouse gas emissions per resident have been reduced by 41%. How has Växjö achieved this impressive result and are there any lessons that could be transferred to Australian cities? This paper describes research which compares Växjö with the Victorian City of Ballarat. The research shows that per capita emissions for Ballarat are 133% higher than those in Växjö. Upgrading the typical Ballarat home to a 6-star rating, and installing a gas-boosted solar water heater and 4.0 kW PV system on the roof could reduce per capita emissions to similar levels to those in Växjö.

Design protection circuit for transformerless photovoltaic inverters in harsh climatic conditions

Transformerless inverters technology in photovoltaic systems offers many advantages, but there are some safety issues due to the solar panel parasitic capacitance. The parasitic capacitance value depends on many factors such as PV panels and frame structure, surface of the cells, distance between the cells, module frame, weather conditions (e.g., humidity) and the amount of dust covering the PV panel. Harsh climate like the one in the Central Queensland region is characterized by high temperature, high relative humidity. Due to the region’s high dew point, high humidity and heavy rain during the wet season, the water condensed over the PV array surface will affect the stray capacitance significantly and consequently, the system leakage current. Human safety in PV system is a key issue, which must be addressed when this technology is applied. Protection against electrical shock is essential while deploying such systems to avoid injury or loss of life. Furthermore, PV insulation varies with meteorological conditions such as, temperatures, humidity. Therefore, the protective circuit should have the capability to adapt to any changes in metrological variables. This paper explorers the effect of meteorological changes on the insulation parameters and leakage capacitance and design a tools for protection.

Simulation and evaluation of HERIC and H5 transformerless inverter topologies

Most of the inverters have an isolation transformer which prevents or limits fault current between AC and DC circuits under most fault conditions. If the transformer is excluded from the system, it would increase the PV system efficiency and decrease the size of its installations, which will lead to a lower cost for the whole investment. Thus, elimination of the transformer has to be considered carefully because a galvanic connection appears between the PV arrays and the ground in the absence of an isolation transformer. The galvanic connection causes the stray capacitance between the PV arrays structure and the ground to produce a leakage current. In this paper, a review of full bridge topology with bipolar and unipolar scheme and half bridge topology carried out in regard leakage current.in addition, HERIC and H5 topologies are simulated and leakage current in these topologies are evaluated.

Robust nonlinear controller design for three-phase grid-connected photovoltaic systems under structured uncertainties

This paper presents a robust nonlinear controller design for a three-phase grid-connected photovoltaic (PV) system to control the current injected into the grid and the dc-link voltage for extracting maximum power from PV units. The controller is designed based on the partial feedback linearization approach, and the robustness of the proposed control scheme is ensured by considering structured uncertainties within the PV system model. An approach for modeling the uncertainties through the satisfaction of matching conditions is provided. The superiority of the proposed robust controller is demonstrated on a test system through simulation results under different system contingencies along with changes in atmospheric conditions. From the simulation results, it is evident that the robust controller provides excellent performance under various operating conditions. © 2014 IEEE.

Low cost MPPT controller for a photovoltaic-based microgrid

 Photovoltaic based microgrid have been increasingly investigated in recent years, ascribable to their fundamental advantages such as the infinite energy source, environmentally friendly aspect and low upkeep cost. However, in practice, they are still considered as an expensive and low output option of renewable energy resources. To extract the maximum possible power from the output of the PV system, a reliable maximum power point tracker (MPPT) is required. Numerous studies have been conducted to introduce the best MPPT techniques suitable for different types of PV systems. However, they are mostly able to track the MPP from the PV system when the output signals (Voltage and Current) of individual array are available. In this study, a meta-heuristic method, based on particle swarm optimization theory, is used to determine the actual MPP of PV system, including several PV arrays, by only single current sensor at the output terminal. The results of the proposed PSO based technique, for tracking the global MPP in a multidimensional search space, have been presented at the end of this paper.

Nonlinear backstepping controller design for sharing active and reactive power in three-phase grid-connected photovoltaic systems

In this paper, a nonlinear backstepping controller is designed for three-phase grid-connected solar photovoltaic (PV) systems to share active and reactive power. A cascaded control structure is considered for the purpose of sharing appropriate amount of power. In this cascaded control structure, the dc-link voltage controller is designed for balancing the power flow within the system and the current controller is designed to shape the grid current into a pure sinusoidal waveform. In order to balance the power flow, it is always essential to maintain a constant voltage across the dc-link capacitor for which an incremental conductance (IC) method is used in this paper. This approach also ensures the operation of solar PV arrays at the maximum power point (MPP) under rapidly changing atmospheric conditions. The proposed current controller is designed to guarantee the current injection into the grid in such a way that the system operates at a power factor other than unity which is essential for sharing active and reactive power. The performance of the proposed backstepping approach is verified on a three-phase grid-connected PV system under different atmospheric conditions. Simulation results show the effectiveness of the proposed control scheme in terms of achieving desired control objectives.

Contribuições ao método de rastreamento de máxima potência para sistemas fotovoltaicos

The scarcity of natural resources and the search for alternative energy sources promote a rapid change in the energy world. Among the renewable energy sources, solar energy is the most promising, presenting technology of greatest growth rate nowadays. Researchers around the world are seeking ways to facilitate their progress, developing technologies with higher efficiency and lower cost. As a contribution to global progress, this master thesis proposes the development of a strategy of maximum power tracking based on perturbation and observation method for photovoltaic systems. The proposed control strategy is based on active power balance of the system, with a reduced number of sensors. It also allows the PV system to act as a regulator of the power quality at the point of commom coupling (PCC), compensating the harmonic distortion and power factor of the current netw

Energy Management and Control for Islanded Microgrid Using Multi-Agents

This paper presents a multi-agent system for real-time operation of simulated microgrid using the Smart-Grid Test Bed at Washington State University. The multi-agent system (MAS) was developed in JADE (Java Agent DEvelopment Framework) which is a Foundation for Intelligent Physical Agents (FIPA) compliant open source multi-agent platform. The proposed operational strategy is mainly focused on using an appropriate energy management and control strategies to improve the operation of an islanded microgrid, formed by photovoltaic (PV) solar energy, batteries and resistive and rotating machines loads. The focus is on resource management and to avoid impact on loads from abrupt variations or interruption that changes the operating conditions. The management and control of the PV system is performed in JADE, while the microgrid model is simulated in RSCAD/RTDS (Real-Time Digital Simulator). Finally, the outcome of simulation studies demonstrated the feasibility of the proposed multi-agent approach for real-time operation of a microgrid.

Diffusion of photovoltaic in Germany: policy vs. consumers

In some countries photovoltaic (PV) technology has already achieved a stage of development at which it can compete with conventional electricity sources. Germany provides a good illustration of this where PV market has reached a mature stage. As a manifest of this, the German government has recently reduced subsidies for households and industry by decreasing the feed in tariff for PV. This development raises fundamental questions: could the PV industry survive? Will consumers be motivated to continue to adopt PV when feed-in tariff diminish? The point of departure for the relevant literature on diffusion of PV has been on the effect of subsidies but little attention has paid to consumer motives when the policy support is scaled down. This paper introduces an in-depth analysis on understanding the consumer motives for adopting photovoltaic applications. Anchored in an extensive exploratory case study on PV consumers and PV system providers, this study aims to provide an encompassing explanation of diffusion of PV by revealing the link between consumer motives and the impact of policy.