Polycrystalline Modules Research Articles

Impact of spectral irradiance distribution on the outdoor performance of photovoltaic system under Thai climatic conditions

This paper presents the effects of spectral irradiance distribution on the performance of polycrystalline (p-Si) and amorphous silicon (a-Si) photovoltaic (PV) modules under Thai climatic conditions. The annual outdoor solar spectrum measurements bouncing on the PV modules installed at Energy Park, School of Renewable Energy Technology (SERT), Naresuan University, Thailand revealed that the average photon energy (APE) of total incident solar irradiance was 50% higher than that at standard test conditions. The results show that the power output of a-Si PV module mainly depends on spectrum distribution. In contrast, the power output of p-Si is not sensitive to spectrum distribution. Because of the different spectrum response of p-Si and a-Si PV modules, the actual irradiance spectrum data of each location under real working conditions are necessary for optimizing PV design.

Dust accumulation effect on efficiency of Si photovoltaic modules

We experimentally studied the electrical efficiency effects of naturally forming atmospheric dust deposits on commercial photovoltaic panels. The variable considered for measurements was the electric potential for three commercial silicon modules: monocrystalline, polycrystalline, and amorphous. A mathematical model was developed to determine maximum potential as a function of temperature and of total incident radiation. The study presents two essential parts: the naturally deposited dust particles and the variation in maximum electric potential between clean and dirty modules. The results indicate that the maximum reduction in potential is around of 6% for monocrystalline and polycrystalline modules and of 12% for the amorphous silicon.

Experimental investigation of the impact of airborne dust deposition on the performance of solar photovoltaic (PV) modules

Abstract Deposition of airborne dust on outdoor photovoltaic (PV) modules may decrease the transmittance of solar cell glazing and cause a significant degradation of solar conversion efficiency of PV modules. Previous studies of this issue indicated that dust deposition is closely related to the tilt angle of solar collector, exposure period, site climate conditions, wind movement and dust properties. However, few studies considered the influence of the properties of PV module itself on dust deposition and efficiency degradation, such as the cell types and surface materials. This experimental work aimed to study the dust accumulation onto different types of solar PV modules and the corresponding efficiency degradation. The experiment was designed and conducted in the laboratory with a sun simulator and a test chamber. The degradation of PV module efficiency caused by dust deposition under various conditions was investigated. The results indicated that dust pollution has a significant impact on PV module output. With dust deposition density increasing from 0 to 22 g m −2 , the corresponding reduction of PV output efficiency grew from 0 to 26%. The reduction of efficiency has a linear relationship with the dust deposition density, and the difference caused by cell types was not obvious. When the dust deposition density was fixed, the reductions of output efficiency at relatively lower or higher solar densities were much more severe. Moreover, the surface material may influence dust deposition and accumulation considerably. The poly-crystalline silicon module packaged with epoxy degraded faster than other modules with glass surface under the same dust concentration.

Study on long term reliability of photo-voltaic modules and analysis of power degradation using accelerated aging tests and electroluminescence technique

Abstract To improve PV module's lifetime and reliability, it is essential to understand the mechanisms and causes that degrade module performance over time under different climatic conditions. In this study, our main aim is to correlate the degradation of module power with physical changes that are generated in the cells over time. The poly-crystalline silicon 200W modules are subjected to long term accelerated tests (testing to be continued until failure occurs) and cell level defects are characterized using electroluminescence (EL) technique. The characterization is done periodically to analyze the trend of physical changes occurring in the module under aggravated stresses and degrading module's performance. Also, change in series resistance under thermal stress is analyzed as it has a direct impact on module's output power. Iterative simulation based software and EL images have been used to estimate series resistance of the cells.

Comparison of Predicted to Measured Photovoltaic Module Performance

To accurately predict the electrical performance of photovoltaic modules computer simulation models are essential. Without such models, potential purchasers of photovoltaic systems have insufficient information to judge the relative merits and cost effectiveness of photovoltaic systems. The purpose of this paper is to compare the predictions of a simulation model, developed by Sandia National Laboratories, to measurements from photovoltaic modules installed in a vertical wall façade in Gaithersburg, MD. The photovoltaic modules were fabricated using monocrystalline, polycrystalline, tandem-junction amorphous, and copper-indium diselenide cells. Polycrystalline modules were constructed using three different glazing materials: 6 mm low-iron glass, 0.05 mm ethylene-tetrafluoroethylene copolymer, and 0.05 mm polyvinylidene fluoride. In order to only assess the simulation model’s ability to predict photovoltaic module performance, measured solar radiation data in the plane of the modules is initially used. Additional comparisons are made using horizontal radiation measurements. The ability of the model to accurately predict the temperature of the photovoltaic cells is investigated by comparing predicted energy production using measured versus predicted photovoltaic cell temperatures. The model was able to predict the measured annual energy production of the photovoltaic modules, with the exception of the tandem-junction amorphous modules, to within 6% using vertical irradiance measurements. The model overpredicted the annual energy production by approximately 14% for the tandem-junction amorphous panels. Using measured horizontal irradiance as input to the simulation model, the agreement between measured and predicted annual energy predictions varied between 1% and 8%, again with the exception of the tandem-junction amorphous silicon modules. The large difference between measured and predicted results for the tandem-junction modules is attributed to performance degradation. Power measurements of the tandem-junction amorphous modules at standard reporting conditions prior to and after exposure revealed a 12% decline. Supplying post exposure module parameters to the model resulted in energy predictions within 5% of measured values.

Direct coupling of an electrolyser to a solar PV system for generating hydrogen

Hydrogen as an energy currency, carrier and storage medium may be a key component of the solution to problems of global warming, poor air quality and dwindling reserves of liquid hydrocarbon fuels. Hydrogen is a flexible storage medium and can be generated by the electrolysis of water. It is particularly advantageous if an electrolyser may be simply and efficiently coupled to a source of renewable electrical energy. This paper examines direct coupling of a polymer electrolyte membrane (PEM) electrolyser to a matched solar photovoltaic (PV) source for hydrogen generation and storage. Such direct coupling with minimum interfacing electronics would lead to substantial cost reduction and thereby enhance the economic viability of solar-hydrogen systems. The electrolyser is designed for fail-safe operation with multiple levels of safety and operational redundancy. A control system in the electrolyser unit provides for disconnection when required and for auto-start in the morning and auto shut-down at night, simultaneously addressing the goals of minimum energy loss and maximum safety. The PV system is a 2.4 kW array (20.4 m 2 total area) comprising 30, 12 V, 80 W, Solarex polycrystalline modules in a series–parallel configuration. The integrated system has been operated for approximately 60 days over a 4-month period from September 2007 to January 2008 with many periods of unattended operation for multiple days, experiencing weather ranging from hot and sunny (above 40 °C) to cool and cloudy. The principle and practicality of direct coupling of a suitably matched PV array and PEM electrolyser have been successfully demonstrated. Details of electrolyser operation coupled to a PV array along with modelling work to match current–voltage characteristics of the electrolyser and PV system are described.

Energy performance of water hybrid PV/T collectors applied to combisystems of Direct Solar Floor type

The integration of photovoltaic (PV) modules in buildings allows one to consider a multifunctional frame and then to reduce the cost by substitution of components. In order to limit the rise of the cell operating temperature, a photovoltaics/thermal (PV/T) collector combines a solar water heating collector and PV cells. The recovered heat energy can be used for heating systems and domestic hot water. A combination with a Direct Solar Floor is studied. Its low operating temperature level is appropriate for the operating conditions of the mono- or poly-crystalline photovoltaic modules which are selected in that study. However, for a system including a glass covered collector and localised in Mâcon area in France, we show that the annual photovoltaic cell efficiency is 6.8% which represents a decrease of 28% in comparison with a conventional non-integrated PV module of 9.4% annual efficiency. This is obviously due to a temperature increase related to the cover. On the other hand, we show that without a glass cover, the efficiency is 10% which is 6% better than a standard module due to the cooling effect. Moreover, in the case of a glazed PV/T collector with a conventional control system for Direct Solar Floor, the maximum temperature reached at the level of the PV modules is higher than 100 °C. This is due to the oversize of the collectors during the summer when the heating needs are null, i.e. without a heated swimming pool for example. This temperature level does not allow the use of EVA resin (ethylene vinyl acetate) in PV modules due to strong risks of degradation. The current solution consists of using amorphous cells or, if we do not enhance the thermal production, uncovered PV/T collector. Further research led to water hybrid PV/T solar collectors as a one-piece component, both reliable and efficient, and including the thermal absorber, the heat exchanger and the photovoltaic functions.

Evaluation of efficiency and degradation of mono- and polycrystalline PV modules under outdoor conditions

This paper presents the experimental results carried out over a period of years of several photovoltaic modules of two basic types, e.g. monocrystalline and polycrystalline, obtained from various sources. These panels were exposed outdoors under the climatic conditions of Bahrain. Our observations show that two of the “first generation” monocrystalline panels completely failed and severe corrosion developed. The rest of the panels show a degradation in efficiency, however polycrystalline modules show a greater drop in output.

Analysis of the VISTA photovoltaic facility-system performance

The performance of the Virginia Integrated Solar Test Arrays is reported and analyzed. The test period reported spans from January 1987 to December 1988. The performance of single-crystal and polycrystalline modules under diverse sky conditions over time while single-axis, two-axis tracking, or fixed tilt arrays are used is examined. Even though the photovoltaic modules performed as expected, the overall outage rates for the two years have ranged from 31.3% to 51.7% for the three subfields. Causes of these outages include PCU trips due to ground fault currents and failures of the insolation recorders, the data acquisition system, the trackers and the modules. The observations suggest that there has not been any significant deterioration of the module performance over this period. >

Design considerations and performance evaluation of the Virginia Integrated Solar Test Arrays

The Virginia Integrated Solar Test Arrays (VISTA) facility was built and is operated by Virginia Power. This 60 kWp (rated) AC photovoltaic (PV) facility consists of three separate 20 kWp AC subfield of different designs providing an opportunity to compare full systems of various tracking mechanisms and cell technologies at one site. Subfield A is comprised of polycrystalline modules arranged on two-axis tracking structures. Subfield B is comprised of polycrystalline modules arranged on fixed-axis structures. Subfield C has single crystal modules and is fixed. At the VISTA facility, commercial-size PV arrays have been interconnected with the grid. This facility has been operational since December 1985, and on-site data collection is ongoing since June 1986. In addition to the design perspective and the system description, the summary of the on-site data collected between June 1986 and March 1987 are presented. It is observed that, over this period, the array and power conditioning until power-conditioning-unit (PCU) efficiencies match closely with design values, and the energy availability factor ranges from 34.80% to 39.99%.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The Polyx photovoltaic technology: progress and prospects

The so-called French « Polyx process » based on moulded multicrystalline silicon ingots is one of the most promising photovoltaic technologies due to its present industrial state and its possible improvements related to costs and conversion efficiency. Multicrystalline ingot processing from polycrystalline feedstock silicon, wafers, cells and module processing are described. Respective roles of basic research at Laboratoires de Marcoussis of CGE and of industrial R & D at Photowatt are analysed. An estimate of costs and prices is given for modules, systems and energy produced both for present and for future state of development of this technology. A description and an analysis of photovoltaic markets well suited to this technology are given, including technology transfer.

Hall effect in thin films of nickel-phosphorus: J Flechon and M Viard,Czech J Phys, B 21 (4/5), 1971, 587–590.

This paper presents a reliable methodology based on imperialist competitive algorithm (ICA) for estimating the optimal parameters of photovoltaic (PV) generating unit. The PV system is simulated by single diode model and double diode model. The proposed constrained objective function is derived from the voltage-power curve of the PV system which has unique maximum power point (MPP). The analysis is performed on different types of PV systems; mono-crystalline, poly-crystalline and amorphous modules. The validation of ICA is investigated for PV cell/module operated under different irradiances and temperatures; the obtained results are compared with experimental data and other reported meta-heuristic optimization algorithms. The results confirm the validity and reliability of ICA in extracting the optimal parameters of the PV generating unit.