Photovoltaic Conversion System Research Articles

Mapping the potential for decentralized energy generation based on renewable energy sources in the Republic of Croatia

There are regions in the Republic of Croatia (underdeveloped, devastated by war, depopulated, as well as islands and mountainous areas) which are still disconnected from the electricity network or where the current network capacity is insufficient. In addition, these regions have good renewable energy potential. Since the decentralized energy generation (DEG) covers a broad range of technologies, including many renewable energy technologies (RET) that provide small-scale power at sites close to the users, this concept could be of interest for these locations. This paper identifies the areas in Croatia where such systems could be applied. Consideration is given to geographical locations as well as possible applications. Wind, hydro, solar photovoltaic, geothermal, and biomass conversion systems were analyzed from a technological and economic point of view. Since the renewable energy sources (RES) data for Croatia are rather scarce, the intention was to give a survey of the present situation and an estimate of future potential for DEG based on RES. The energy potential (given as capacity and energy capability) and production costs were calculated on a regional basis and per type of RET. Finally, the RES cost-supply curves for 2006 and 2010 are given.

Mapping the potential for decentralized energy generation based on RES in Western Balkans

Although the countries of the Western Balkans are mostly electrified, there are still regions which do not have access to the electricity network or where the network capacity is insufficient. For the most part such areas are under special care of the state (i. e. underdeveloped, devastated by war, depopulated), on islands or in mountainous regions. Since the decentralized energy generation covers a broad range of technologies, including many renewable energy technologies that provide small-scale power at sites close to the users, such concept could be of interest for these locations. This paper identifies the areas in Western Balkans where such systems could be applied. Consideration is given to geographical locations as well as possible applications. Wind, hydro, solar photovoltaic, and biomass conversion systems were taken into consideration. Since the renewable energy sources data for Western Balkans region are rather scarce, the intention was to give a survey of the present situation and an estimate of future potential for decentralized energy generation based on renewable energy sources. The decentralized energy generation based on renewable energy sources in Western Balkans will find its niche easier for the users that will produce electricity for their own needs and for the users located in remote rural areas (off-grid applications).

Near-IR Light-Sensitized Voltaic Conversion System Using Nanocrystalline TiO2 Film by Zn Chlorophyll Derivative Aggregate

A Zn chlorophyll-a derivative, Zn chlorin-e6 (ZnChl-e6), adsorbed onto a nanocrystalline TiO2 film (ZnChl-e6/TiO2) electrode was prepared, and the photovoltaic properties of the ZnChl-e6/TiO2 electrode were studied. The absorption peaks of ZnChl-e6/TiO2 observed at 420, 654, and 795 nm were attributed to the ZnChl-e6 molecules aggregating onto TiO2 film. The fluorescence attributed to the ZnChl-e6 monomer and aggregate was observed at 710 and 820 nm, respectively, and the fluorescence in both cases was quenched by TiO2 particles. The maximum of the incident photon-to-current conversion efficiency (IPCE) value in the photocurrent action spectrum was 800 nm, and the IPCE value was 7.0%. ZnChl-e6 molecules formed aggregates on a nanocrystalline TiO2 film electrode. From the photocurrent-photovoltage characteristics of the ZnChl-e6/TiO2 electrode irradiated with 100 mW cm(-2), the short-circuit photocurrent (I(SC)) was found to be 0.19 mA cm(-2) and the open-circuit photovoltage (V(OC)) was found to be 375 mV. The maximum power was estimated to be 28.7 microW cm(-2), and the fill factor (FF) was estimated to be 40.1%. A near-IR light induced photovoltaic conversion system using a ZnChl-e6 aggregate formed onto a nanocrystalline TiO2 film electrode was achieved.

On the stability of DC-to-DC converters in photovoltaic systems undergoing sliding motions

This paper deals with the dynamic behaviour of different DC-to-DC switching electronic converters in photovoltaic applications. In particular, the ability of the DC-to-DC converters to accomplish regulation of certain circuit variables, which are related to the control objectives, is examined. This task is addressed from a variable structure system approach. With this aim, the feasibility of establishing stable sliding regimes on different state co-ordinate surfaces is investigated. Differences in the dynamic behaviour of the DC-to-DC switching converters between photovoltaic and conventional power-supply applications are stressed.

Photovoltaic converter system suitable for use in small scale stand-alone or grid connected applications

Of the commercially-available solutions for the conversion of energy from photovoltaic arrays into a usable form, a large number consist of systems which have been developed for a dedicated application and are thus very inflexible. Those that are available as a generic module for use in a variety of environments are often restricted to a single mode of operation, for example utility supply only. A generic modular photovoltaic power conversion system is presented, aimed at single-phase applications which can supply passive AC and DC loads with a regulated voltage or by way of a maximum power tracking system with the maximum power available from the array. In addition a live AC load such as the utility can be supplied with maximum array power. The system is small, light and can be constructed from readily available components.

PV Solar Systems and Development of Semiconductor Materials

Photovoltaic conversion (PV) of solar energy based on the solar cells, is becoming acceptable for various applications. One of the most up-to-date semiconductor technologies, it enables development of the systems for lighting, supplying electrical energy to radio and TV stations. electromotors (kW power) for wide application in industry, agriculture and individual homes. for refrigerators for different purposes etc. The bases of this technology are semiconductor materials. In this paper we analyze the influence of the basic semiconductor materials on further increase of applications of PV systems.

The calculation of available solar energy for design of photothermal and photovoltaic conversion systems

SYNOPSIS The available surface density of total solar radiation can be suitably calculated by the SOLEN method. The basic principles and relations of the mathematical model used in the SOLEN method are introduced. The universal SOLEN method enables calculation of the amount of solar energy incident on an arbitary tilted and orientated surface and transmitted through glazing for a chosen month. The SOLEN method uses the average monthly value of the relative sunshine duration, taking into account the mean real cloudiness of the respective geographical locality. The mean monthly values of available surface density of total solar radiation calculated for two localities are compared to the experimental observation data. An illustration of the way to use the calculated results for the determination of the optimum tilt of stable located solar-cell panels and flat-plate solar thermal collectors is also included.

Die ontwikkeling en implementering van ’n saamgestelde omsetter vir gebruik in sonenergiestelsels

The converter proposed here is a compound photovoltaic converter system that has been implemented with a power rating of 1,5 kVA at an array voltage of 96 V, using a 24 V battery bank. The converter system combines the functions of inversion, battery regulation and maximum power point tracking of the solar array into a single cost-effective converter. Maximum power point tracking is performed by controlling the voltage and frequency of the AC output. A description of this converter, and an explanation of the control strategy employed, are provided together with practical results measured on the prototype converter. This compound topology has a high conversion efficiency from solar array to load.

Investigation of potential islanding problems of a line-commutated static power converter in photovoltaic systems

The results of a research project on the possible islanding operation of a section of a distribution feeder containing line-commutated static power converters are reported. The project's approach is to develop a computer model of the static power converter (SPC) to predict islanding operation and verify the model with laboratory and field tests. The computer model accurately predicts the operation of the SPC during islanding. The effect of general system parameters on the islanding performance of the Gemini line-commutated SPC are presented. The most important factor which determines the characteristics of the island is the mismatch of watts and Vars at the time the island is formed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Investigation of potential islanding of a self-commutated static power converter in photovoltaic systems

A summary is presented of the results of a research project on the islanding potential of a Teslaco self-commutated static power converter (SPC). This project included computer simulations, laboratory testing, and field testing. Laboratory and field tests verified that the SPC model developed for computer simulations accurately predicts SPC islanding performance under a variety of system conditions. The impact of a number of system parameters on the islanding potential of a Teslaco SPC are presented. These include the mismatch between load and generation within the island, the type of load within the island, the number of SPCs within the island, load variations, and solar insolation variations.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Parametric study of laser photovoltaic energy converters

Photovoltaic converters are of interest for converting laser power to electrical power in a space-based laser power system. This paper describes a model for photovoltaic laser converters and the application of this model to a neodymium laser silicon photovoltaic converter system. A parametric study which defines the sensitivity of the photovoltaic parameters is described. An optimized silicon photovoltaic converter has an efficiency greater than 50% for 1 × 10 3 W cm −2 of neodymium laser radiation.

A High-Frequency Inverter Cycloconverter Cascade

A conversion technique using high-frequency inverters and cycloconverters is presented. The technique has application to battery charger and inverter applications. The high operating frequencies and reversible nature of the converters can result in significant cost, weight, and size reductions. The technique is applied to produce high-efficiency converters for photovoltaic systems. Results for a 6-kVA 110-Vdc/240-Vac single-phase converter are presented. The converter consists of two phase square wave inverters supplying a four-pulse cycloconverter stage. A peak conversion efficiency of 95 percent is achieved with a total output distortion below 3 percent. Standing losses are extremely low, being approximately 1 percent of the converter rating. The converters are reversible by nature and operation as an ac-dc intertie is possible.

Optimization of a combined wind and solar power plant

The paper is concerned with determining the optimized active areas of a photovoltaic conversion system, of a group of electricity generating wind machines and the optimal capacity of a battery storage system for a combined power plant. Minimization of the total life-cycle cost of the system is the criterion to obtaining the optimized parameters of the system. The algorithm consists of generating the system costs corresponding to various values of the parameters and to use these costs in a search procedure to determine the minimum. Each point is generated by a simulation program describing the system behaviour.