Silicon-based Photovoltaic Modules Research Articles

Life cycle climate performance of photovoltaic power plant for Turkey’s solar power conditions

ABSTRACT In this study, a solar power plant with an output power of 10 kW AC was designed according to the Turkish Electricity Legislation. Silicon-based photovoltaic modules were used in the design. The solar power plant’s annual and lifetime electricity generation was calculated for 81 provinces of Turkey. The study contributes significantly to the literature by evaluating the environmental impacts of energy sources in a more realistic way. According to the electricity generation calculations, the power plant in Trabzon generates a minimum of 13,037 kWh of electricity per year. In comparison, the power plant in Antalya generates a maximum of 18,562 kWh. Over the plant’s life, Antalya will generate 464,040 kWh of electricity and Trabzon will generate 325,929 kWh. The life cycle climate performance technique was used to understand the environmental impacts during the installation phase, and these values were determined to be 5759 kgCO2. Emission values from electricity generation vary between 0.01241 and 0.01767 kgCO2 per kWh. These data provide a comprehensive assessment of the environmental impacts of solar power plants. This study contributes to the literature by investigating the potential and environmental effects of solar energy in different regions of Turkey in detail. In particular, presenting the emission values of electricity generation from photovoltaic systems for each province provides valuable data that can be used in shaping energy policies and developing environmental strategies. This unique study will provide a scientific basis for planning and implementing solar energy investments in Turkey and contribute significantly to developing energy policies and environmental strategies.

Optical interference coatings for coloured building integrated photovoltaic modules: Predicting and optimising visual properties and efficiency

The presented work is focusing on optical interference coatings on the back side of the front glass for crystalline silicon-based photovoltaic modules. We present results on how such coatings can be designed to obtain desired visual properties combined with a limited loss in power conversion efficiency. This colouring technology may therefore be very attractive for building integrated photovoltaics. Coating design parameters such as number of layers, design wavelength, layer thicknesses, and layer refractive indices affect both the visual appearance parameters and the efficiency. Important colour parameters are lightness, chroma, and hue, and we demonstrate how these colour parameters are influenced by the design parameters of the optical interference coating.Using optical interference coatings to create colours results in colours that are dependent on the observation angle. We have introduced a new parameter for quantification of angular colour dependence. Our results show that the angular colour dependence can be reduced by increasing the refractive indices of the interference coating.For many building projects it may be highly desired to combine high power conversion efficiency with certain visual properties. The results from our work also indicate some of the possibilities and challenges in this regard.

Multilayered PCMs-based cooling solution for photovoltaic modules: Modelling and experimental study

The higher operational temperature during the Indian summer reduces the power conversion efficiency (PCE) of Silicon-based photovoltaic (PV) modules and also shortens their lifetime. Recently, phase change materials (PCMs) have been used as a passive cooling technique that can bring down the temperature of PV modules. In this study, we investigated the multilayered PCM system that can render thermal management in all seasons, owing to the combination of low and high melting point PCMs. The previous studies conducted on these multilayered PCMs have only performed simulations to evaluate these systems, and to the best of our knowledge, systematic experiments have not been performed to establish the merit of multi-layer PCM arrangement. Experiments on multilayered PCM showed a lower maximum temperature of PV module by 4 °C and 7.2 °C when compared to single-layer PCM and PV reference respectively. Theoretical calculations indicate that using the multilayered PCM system can successfully regulate the operating temperature of PV modules in all seasons with 3.3% higher yearly electric output, extend PV life by almost ten years and nearly double the lifetime earnings. Therefore, this work lays the groundwork for the commercialization of thermal management systems for PV modules using the multilayered PCM approach.

Influence of outdoor conditions on PV module performance – an overview

The utilization of renewable sources of energy is of significant interest today. This is particularly the case due to the growing interest in addressing global warming, carbon footprint and the associated challenges for the environment. In this context, the enhanced use of solar panels is relevant and timely. With a view to understand and appreciate the fundamentals of the workings of the solar panels and the influence of the outdoor weather-related parameters on their operational characteristics, a study is presented in this paper. A detailed procedure for performance measurement of PV modules in outdoor conditions is reported. Improvement in the precision of outdoor performance measurements of photovoltaic (PV) modules is investigated for a wide range of outdoor conditions. A comparative performance evaluation of the currently available PV modules under the influence of humidity, irradiance and particle radiation is presented. PV parameters show strong dependence on these outdoor conditions. The instability in solar cell modules when reacting with water or under high humidity inhibits the high performance of solar cell modules. Irradiation results depict that the silicon-based PV modules show a decreasing trend of power conversion efficiency with increasing solar irradiance. The efficiency increases with increased solar irradiance for CdTe, GaAs and CIGS solar cells in the irradiance range of 200 to 1000 W•m-2. Tandem and multi-junction solar cells exhibit a high-power conversion efficiency when the solar irradiance increases from 0 - 70 suns. Perovskite solar cells have better particle radiation tolerance than silicon, III-V and CIGS solar cells. The shading problem is discussed briefly for solar cell modules. This study is aimed to provide valuable and comparable information on the degradation performance of solar cells as function of humidity, irradiance and particle radiation, and serves as the basis for future development.

Degradation analysis of highly UV-resistant down-shifting layers for silicon-based PV module applications

In this work, the external quantum efficiency (EQE) of [Eu(bta)3me-phen] downshifters (DS) encapsulated by industrial procedures on photovoltaic (PV) modules is presented. The samples have been laminated using the DS layers faced-up and faced-down. The results obtained for the DS layers present an EQE enhancement of 1.2 % for the faced-up samples and 0.8 % for the faced-down samples. A climate chamber was used to evaluate the EQE performance during the ageing process; a temperature of 22 °C and relative humidity of 30 % was fixed. Several time cycles have been used to achieve a total UV dose of 454.94 kWh. After a 136.51 kWh dose, the increment of the EQE for the faced-up samples vanishes. In contrast, after a dose of 454.94 kWh, the EQE enhancement for samples with the DS layer faced down remains unaltered.

Long-term examinations up to 20 years of performance ratio and degradation rate of different-type photovoltaic modules at central part of Japan

Performance ratio and degradation rate of various-type silicon-based photovoltaic modules, which are multi-crystalline silicon, amorphous silicon, amorphous silicon/multi-crystalline silicon tandem, and amorphous silicon/amorphous silicon germanium/amorphous silicon germanium three-stack, were investigated after long exposure period up to about 20 years from 2000 to 2020 at outdoor site in Shiga-prefecture, Japan. Moreover, meteorological elements such as ambient temperature, and solar irradiance at outdoor location were investigated for approximately 20 years. Outdoor spectral distribution was observed in a year. It is disclosed that monthly performance ratio of multi-crystalline silicon module is inversely proportional to ambient temperature, whereas that of the amorphous silicon and tandem modules is positively proportional to ambient temperature. Degradation rate of the amorphous silicon module is the highest (3.776 %/year), and that of the tandem module is the second highest (1.338 %/year) of all silicon-based silicon modules after light exposure in the first period of the installation of the modules (≤10 years), implying performance ratio of amorphous silicon and tandem modules are more decreased than other type (multi-crystalline silicon and three-stack) modules. With longer years of the installation up to 20 years, degradation rate of each type of the modules is further decreased, suggesting that silicon-based modules become more stable after longer light exposure time.

How Much Photovoltaic Efficiency Is Enough?

At present, the purchasing prices for silicon-based photovoltaic modules with 20% efficiency and more are between 20 and 40 EURct/Wp. These numbers correspond to 40 to 80 EUR/m2 and are in the same range as the mounting costs (material prices plus salaries) of such modules. Installers and operators of photovoltaic systems carefully balance the module and mounting costs when deciding among modules of different efficiencies. This contribution emulates the installer’s decision via a simple, analytical module mounting decision (Mo2De) model. A priori, the model, and the resulting conclusions are completely independent of the photovoltaically active material inside the modules. De facto, however, based on the present state (cost, efficiency, reliability, bankability, etc.) of modules fabricated from (single) crystalline Si cells, conclusions on other photovoltaic materials might also be drawn: On the one hand, the model suggests that lower-efficiency modules with efficiencies below 20% will be driven out of the market. Keeping in mind their installation costs, installers will ask for large discounts for lower-efficiency modules. Technologies based on organic semiconductors, CdTe, CIGS, and even multicrystalline Si, might not survive in the utility market, or in industrial and residential applications. Moreover, this 20% mark will soon reach 23%, and finally will stop at around 25% for the very best, large-area (square meter sized) commercial modules based on single crystalline silicon only. On the other hand, it also seems difficult for future higher-efficiency modules based on tandem/triple cells to compete with standard Si-based reference modules. Compared to their expected higher efficiency, the production costs of tandem/triple cell modules and, therefore, also their required markup in sales, might be too high. Depending on the mounting cost, the Mo2De-model predicts acceptable markup values of 1 EURct/Wp (for low mounting costs of around 10 EUR/m2) to 11 EURct/Wp (for high mounting costs of 100 EUR/m2) if the module efficiency increases from 23% to 30%. Therefore, a 23% to 24% module efficiency, which is possible with silicon cells alone, might be enough for many terrestrial photovoltaic applications.

Spectral conversion by silicon nanocrystal dispersed gel glass: efficiency enhancement of silicon solar cell

Alongside the quest for new materials for development of next-generation solar cells, increasing the efficiency of the existing crystalline silicon-based photovoltaic module is of paramount importance. In this work we prepared a silicon nanocrystal (NC) dispersed gel-glass and used it as a luminescent down shifting material to enhance the efficiency of a conventional solar cell module. The synthesized gel-glass efficiently converts the unutilized high energy UV photons of the solar spectrum to blue-green photons and renders them amenable for effective carrier generation. An exceptionally high quantum yield (42.8%) of photon down conversion could be achieved with the luminescent silicon NCs. Following the insertion of the NC embedded gel-glass, the relative photon conversion efficiency and the short circuit current of the solar cell were found to increase by 6.48% and 4.2%, respectively. Further improvement of solar cell efficiency using this material could be achieved by optimized design and deposition and by optimizing the formation parameters of the gel-glass.

An Experimental and Comparative Performance Evaluation of a Hybrid Photovoltaic-Thermoelectric System

The majority of incident solar irradiance causes thermalization in photovoltaic (PV) cells, attenuating their efficiency. In order to use solar energy on a large scale and reduce carbon emissions, their efficiency must be enhanced. Effective thermal management can be utilized to generate additional electrical power while simultaneously improving photovoltaic efficiency. In this work, an experimental model of a hybrid photovoltaic-thermoelectric generation (PV-TEG) system is developed. Ten bismuth telluride-based thermoelectric modules are attached to the rear side of a 10 W polycrystalline silicon-based photovoltaic module in order to recover and transform waste thermal energy to usable electrical energy, ultimately cooling the PV cells. The experiment was then carried out for 10 days in Lahore, Pakistan, on both a simple PV module and a hybrid PV-TEG system. The findings revealed that a hybrid system has boosted PV module output power and conversion efficiency. The operating temperature of the PV module in the hybrid system is reduced by 5.5%, from 55°C to 52°C. Due to a drop in temperature and the addition of some recovered energy by thermoelectric modules, the total output power and conversion efficiency of the system increased. The hybrid system’s cumulative output power increased by 19% from 8.78 to 10.84 W, compared to the simple PV system. Also, the efficiency of the hybrid PV-TEG system increased from 11.6 to 14%, which is an increase of 17% overall. The results of this research could provide consideration for designing commercial hybrid PV-TEG systems.

Solar photovoltaic module detection using laboratory and airborne imaging spectroscopy data

Over the past decades, solar panels have been widely used to harvest solar energy owing to the decreased cost of silicon-based photovoltaic (PV) modules, and therefore it is essential to remotely map and monitor the presence of solar PV modules. Many studies have explored on PV module detection based on color aerial photography and manual photo interpretation. Imaging spectroscopy data are capable of providing detailed spectral information to identify the spectral features of PV, and thus potentially become a promising resource for automated and operational PV detection. However, PV detection with imaging spectroscopy data must cope with the vast spectral diversity of surface materials, which is commonly divided into spectral intra-class variability and inter-class similarity. We have developed an approach to detect PV modules based on their physical absorption and reflection characteristics using airborne imaging spectroscopy data. A large database was implemented for training and validating the approach, including spectra-goniometric measurements of PV modules and other materials, a HyMap image spectral library containing 31 materials with 5627 spectra, and HySpex imaging spectroscopy data sets covering Oldenburg, Germany. By normalizing the widely used Hydrocarbon Index (HI), we solved the intra-class variability caused by different detection angles, and validated it against the spectra-goniometric measurements. Knowing that PV modules are composed of materials with different transparencies, we used a group of spectral indices and investigated their interdependencies for PV detection with implementing the image spectral library. Finally, six well-trained spectral indices were applied to HySpex data acquired in Oldenburg, Germany, yielding an overall PV map. Four subsets were selected for validation and achieved overall accuracies, producer's accuracies and user's accuracies, respectively. This physics-based approach was validated against a large database collected from multiple platforms (laboratory measurements, airborne imaging spectroscopy data), thus providing a robust, transferable and applicable way to detect PV modules using imaging spectroscopy data. We aim to create greater awareness of the potential importance and applicability of airborne and spaceborne imaging spectroscopy data for PV modules identification.

Water Conservation Potential of Self-Funded Foam-Based Flexible Surface-Mounted Floatovoltaics

A potential solution to the coupled water–energy–food challenges in land use is the concept of floating photovoltaics or floatovoltaics (FPV). In this study, a new approach to FPV is investigated using a flexible crystalline silicon-based photovoltaic (PV) module backed with foam, which is less expensive than conventional pontoon-based FPV. This novel form of FPV is tested experimentally for operating temperature and performance and is analyzed for water-savings using an evaporation calculation adapted from the Penman–Monteith model. The results show that the foam-backed FPV had a lower operating temperature than conventional pontoon-based FPV, and thus a 3.5% higher energy output per unit power. Therefore, foam-based FPV provides a potentially profitable means of reducing water evaporation in the world’s at-risk bodies of fresh water. The case study of Lake Mead found that if 10% of the lake was covered with foam-backed FPV, there would be enough water conserved and electricity generated to service Las Vegas and Reno combined. At 50% coverage, the foam-backed FPV would provide over 127 TWh of clean solar electricity and 633.22 million m3 of water savings, which would provide enough electricity to retire 11% of the polluting coal-fired plants in the U.S. and provide water for over five million Americans, annually.

Radiation-Thermodynamic Modelling and Simulating the Core of a Thermophotovoltaic System

Thermophotovoltaic (TPV) systems generate electricity without the limitations of radiation intermittency, which is the case in solar photovoltaic systems. As energy demands steadily increase, there is a need to improve the conversion dynamics of TPV systems. Consequently, this study proposes a novel radiation-thermodynamic model to gain insights into the thermodynamics of TPV systems. After validating the model, parametric studies were performed to study the dependence of power generation attributes on the radiator and PV cell temperatures. Our results indicated that a silicon-based photovoltaic (PV) module could produce a power density output, thermal losses, and maximum voltage of 115.68 W cm−2, 18.14 W cm−2, and 36 V, respectively, at a radiator and PV cell temperature of 1800 K and 300 K. Power density output increased when the radiator temperature increased; however, the open circuit voltage degraded when the temperature of the TPV cells increased. Overall, for an 80 W PV module, there was a potential for improving the power generation capacity by 45% if the TPV system operated at a radiator and PV cell temperature of 1800 K and 300 K, respectively. The thermal efficiency of the TPV system varied with the temperature of the PV cell and radiator.

Numerical analysis of the reliability of photovoltaic modules based on the fatigue life of the copper interconnects

A typical photovoltaic (PV) module is composed of different layers bonded together, each with a different material and thus, a different coefficient of thermal expansion (CTE). While under operation, it is subjected to thermal loads due to continuous temperature variations. The CTE mismatch induces thermo-mechanical stresses, whose cyclic nature causes fatigue failure. Due to their relative small size, the copper interconnects are one of the most vulnerable constituents.In this work, the finite element (FE) analysis has been used to calculate these thermal stress/strain variations. To make the simulations more reliable, well-known material models have been adopted from the literature and used for each constituent of the PV module. Furthermore, to reduce computational time and complexity, a simplified modeling approach has been proposed in this work. In this approach, a 2-D FE global model was first used to identify the region that undergoes maximum strain. Then a 3-D FE local model was used for that particular region only. This approach helps calculate the maximum stress/strain variations. Thus, using the proposed modeling approach coupled with a fatigue criterion, one can calculate the fatigue life of the PV module, while significantly reducing the computational time. The initial conditions, in terms of residual stresses, due to the lamination process for the fabrications of the PV module are also accounted for in our approach. We applied our approach to silicon-based PV module under desert weather conditions of Doha (Qatar) and the results show a reduced life compared to the one provided by the manufacturer.

Thermal management of solar PV module by using hollow rectangular aluminum fins

Some of the recent challenges encountered in research and development of the solar photovoltaic (PV) industry include the decrease in electrical output efficiency of a conventional solar PV module due to the rise in its surface temperature. The main objective of this research work is to enhance and improve the electrical output efficiency of a common silicon-based solar PV module by lowering the operating temperature of the PV module, which was accomplished by attaching hollow rectangular aluminum tubes as a fin to the rear surface of the solar PV panel. The proposed geometrical configuration of tubes helped to increase the PV module heat transfer rate to the surrounding air by increasing the effective heat transfer area without increasing the overall weight of the PV module. In this experimental study, a comparative analysis has been presented for PV modules with fins and without fins. The results obtained from experiments demonstrated that the attached fins reduced the average temperature of the front and rear surfaces up to 8.97% and 8.41%, respectively. The cooling effect produced due to fins improved the open circuit voltage up to 12.97% and the electrical output efficiency up to 2.08%. Furthermore, the results are thoroughly compared with other published studies, which revealed that the proposed configuration is cost effective and structurally sound.

Experimental investigation of sandwich glazed solar photovoltaic module

The light and heat energies from the sun are directly converted into electricity either by directly using solar photovoltaic (SPV) module or indirectly using concentrated solar technology system. Photovoltaic (PV) cells is a semiconductor device which is sensitive to temperature. The energy gap of the silicon material reduces when its temperature increases. The decrease in the energy gap of the silicon semiconductor with increasing working temperature can affect the performance of the PV cell. In this article, the working temperature of commercial grade silicon-based solar photovoltaic module as well as sandwich glazed solar photovoltaic module and its impact upon the electricity delivered is discussed. The significant effects of operating temperature, irradiation and wind speed on the PV module temperature were presented. These parameters were used to estimate the electrical performance of the commercial and sandwich glazed PV modules.

In-field monitoring of eight photovoltaic plants: degradation rate along seven years of continuous operation

<p class="Abstract">The results of more than seven years (October 2010-December 2017) of continuous monitoring are presented in this paper. Eight outdoor photovoltaic (PV) plants were monitored. The monitored plants use different technologies: mono-crystalline silicon (m-Si), poli-crystalline silicon (p-Si), string ribbon silicon, copper indium gallium selenide (CIGS), thin film, and cadmium telluride (CdTe) thin film. The thin-film and m-Si modules are used both in fixed installations and on x-y tracking systems. The results are expressed in terms of the degradation rate of the efficiency of each PV plant, which is estimated using the measurements provided by a multi-channel data acquisition system that senses both electrical and environmental quantities. A comparison with the electrical characterization of each plant obtained by means of the transient charge of a capacitive load is also made. In addition, three of the monitored plants are characterized at module level, and the estimated degradation rates are compared to the values obtained with the monitoring system. The main outcome of this work can be summarized as the higher degradation rate of thin-film based PV modules with respect to silicon-based PV modules.</p>

Micro-Segregated Liquid Crystal Haze Films for Photovoltaic Applications: A Novel Strategy to Fabricate Haze Films Employing Liquid Crystal Technology.

Herein, a novel strategy to fabricate haze films employing liquid crystal (LC) technology for photovoltaic (PV) applications is reported. We fabricated a high optical haze film composed of low-molecular LCs and polymer and applied the film to improve the energy conversion efficiency of PV module. The technique utilized to fabricate our haze film is based on spontaneous polymerization-induced phase separation between LCs and polymers. With optimized fabrication conditions, the haze film exhibited an optical haze value over 95% at 550 nm. By simply attaching our haze film onto the front surface of a silicon-based PV module, an overall average enhancement of 2.8% in power conversion efficiency was achieved in comparison with a PV module without our haze film.

Techno-economic viability of silicon-based tandem photovoltaic modules in the United States

Tandem photovoltaic modules with silicon bottom cells offer a promising route to exceed the single-junction photovoltaic efficiency limit and further lower the levelized cost of solar electricity. However, it is unclear whether continued improvements in efficiency will render tandem modules cost-competitive with their two constituent sub-cells, and with silicon technology in particular. Here, we construct a simple and versatile techno-economic model that, for a given balance-of-systems scenario, calculates the tandem module efficiency and cost from assumed sub-cell module efficiencies and costs. To understand which input conditions are likely to be representative of the future photovoltaic market, we calculate learning rates for both module and area-related balance-of-system costs, and find that the slower learning rate of the latter means that high-efficiency tandems will become increasingly attractive. Further, in the residential market in 2020, the model indicates that top-cell modules could cost up to US$100 m–2—over twice that of the projected silicon module cost—and the associated tandem module would be cost-competitive if its energy yield, degradation rate, service life and financing terms are similar to those of silicon. One way to overcome the theoretical efficiency limit of silicon photovoltaics is to use them as the bottom cell in a tandem photovoltaic module. Here a model for tandem module efficiency and cost is presented, based on assumed sub-cell efficiencies and costs, and used to examine possible paths for different tandem markets.

Evaluation of the performance and degradation of crystalline silicon-based photovoltaic modules in the Saharan environment

The aim of this paper is to present three years of an evaluation of the performance and degradation rate of three different crystalline silicon-based photovoltaic (PV) modules in the Saharan environment. The PV modules are: mc-Si (multi-crystalline), c_Si (mono-crystalline, back contacted) and HiT (heterojunction with intrinsic thin-layer); they are installed in Saida which is located at the proximity of Algeria’s Sahara. Two methods were used to calculate the degradation rate; the effective peak power of the PV modules and the temperature corrected performance ratio. It was found that the HIT technology performs worse than the other technologies with the highest degradation rate, ranging from −1.53%/year to −1.92%/year. The mc_Si PV and c_Si PV module technologies present a lower degradation rate than the HIT technology in the range of −0.74%/year to −0.83%/year and −0.58%/year to −0.79%/year respectively.

Recycling Waste Crystalline Silicon Photovoltaic Modules by Electrostatic Separation

Photovoltaic (PV) modules contain both valuable and hazardous materials, which makes their recycling meaningful economically and environmentally. The recycling of the waste of PV modules is being studied and implemented in several countries. Current available recycling procedures include either the use of high-temperature processes, the use of leaching agents or a combination of both. In this study, waste of silicon-based PV modules are separated using an electrostatic separator after mechanical milling. An empirical study is used to verify if the separation works and to select and fix several parameters. Rotation speed of the roller and DC voltage are evaluated as a result of the separation of metals (silver and copper), silicon, glass, and polymers. The efficiency of metals’ separation is determined by acid leaching of the corresponding fractions followed by inductively coupled plasma optical emission spectrometry (ICP-OES); that of polymer separation is determined by mass difference due to combustion of the corresponding fractions; and those of glass and silicon quantities are determined by X-ray diffraction (XRD) followed by characterization using Rietveld quantitative phase analysis (RQPA). It is shown that the optimal separation is obtained under different operating voltages of 24 and 28 kV and a rotation speed of 30 RPM or higher. Furthermore, it is shown that there is no significant difference among the tested parameters. Results provide a new option in the recycling of waste of silicon PV modules that can and should be optimized.