Floating solar stations

According to International Energy Agency, solar photovoltaic deployment levels were globally high in 2020 in the midst of 90% grow in renewable electricity demand5. Photovoltaic (PV) can directly convert sunlight to electricity. From photovoltaic point of view, as can be seen Figure 1, there are four main factors influencing the output PV energy yield. First is the source of energy, the sunlight, then the converter which is the PV cell, further the amount of time that the PV unit can work, and finally the amount of area that PV technology is added on or integrated into. Sunlight is a given, we do not have much control on it. On top of that, PV converter efficiency is reaching its maximum theoretical efficiency6/7. And that is why researchers have now put more effort into investigating approaches to boost the lifetime of PV (the factor time)8 and also looking into possibilities to add PV on or integrated it into any possible surface (the factor area)9. However, due to low efficiency of PV modules, they occupy considerable amount of area, which can be used for other essential needs of human kind, such as food and accommodation. World population is growing and the demand for food, accommodation, and green energy is also increasing. Therefore, agriculture and energy sectors might compete or already are competing over land. This inevitably brings the attention to another vastly available surface area, the water. Simply placing any type of PV system on top of (or even submerged into) water bodies, such as lakes, reservoirs, hydroelectric dams, industrial and irrigation ponds, and coastal lagoons, is called floating PV (FPV) or floatovoltaics.Photovoltaic Materials and Device

Effect of thermal radiation entropy on the outdoor efficiency limit of single-junction silicon solar cells

Incoming radiation energy illuminating a solar cell contains a certain amount of entropy, which does not contribute to output electrical work. Entropy has a different spectral distribution from the internal energy of light and consequently affects PV cell performance. Here in this work, we investigate the influence of entropy content of thermally radiated light on the maximum achievable efficiency of single-junction solar cells. We revise the value of the well-known Shockley-Queisser (SQ) limit for various absorber materials and take a deeper look at this effect by re-calculating the efficiency limit of crystalline silicon solar cells considering Meitner-Auger recombination. When considering the entropy content of AM 1.5 standard spectrum, the SQ limit for silicon drops from 33.15% to 30.42%. Further, considering Meitner-Auger recombination and using measured properties of silicon, the efficiency limit lowers to 27.12% from the already established 29.43%. This suggests a 4% thinner silicon absorber, reaching a thickness of ∼101 μm; hinting PV industry that a thinner Si wafer can provide the optimum outdoor energy yield. We further show that the entropy content of terrestrial radiation is less in favor of c-Si technology and most in favor of amorphous silicon. In the end, we discuss a few applications of considering entropy of incoming sunlight for photovoltaics, which range from PV device design to PV module tilt optimization and even PV system electrical standards.Photovoltaic Materials and Device

Growth and viability of yogurt starter organisms in honey-sweetened skimmed milk

Lactic acid bacteria (LAB): Streptococcus thermophilus TA 040 and Lactobacillus delbrueckii spp. bulgaricus Lb 340, were cultured in reconstituted (10%, w/v) skimmed milk with 5 or 10% (w/v) polyfloralor unifloral honey. Inoculated samples were incubated aerobically at 42°C until milk coagulation. Samples were collected at 2 h intervals and examined for biomass and pH changes. Cell viability and post-acidifying activity of both strains during 28 days of storage at 4°C were also measured. A higher increase (

Photovoltaic Potential of the Dutch Inland Shipping Fleet: An Experimentally Validated Method to Simulate the Power Series from Vessel-Integrated Photovoltaics

The surface of the vessels, as moving tiny islands, can be utilized to implement vehicle-integrated photovoltaics (VIPV). Herein, a methodology is reported to calculate the power generated by a fleet of urban vessels as a function of time. Then, the result is shown for the largest European shipping fleet, using sailing data of 2746 Dutch general cargo vessels. Results show that the studied fleet can produce ≈ 226 GWh of energy per year, which corresponds to ≈ 6.5% of the whole fleet's energy demand. Next, this research validates the model with three week experimental data gathered by a test vessel sailing through the Netherlands. The validation phase reveals that the model can predict within a 4% error range. Finally, as an interesting finding, it is experimentally shown that the energy production profile of a fleet of urban vessels follows a Weibull distribution, quantified by scale (λ) and shape (k) parameters: λ = 880 Wh Wp−1 and k = 27 for the Dutch fleet. A sensitivity analysis shows that the parameters of the Weibull distribution are a function of urban fabric roughness and the climate. Such probability distribution can be extended to other urban fleets, such as solar cars, and help estimate the financial feasibility of integrating PV into vehicles.Photovoltaic Materials and Device

A Simple and Novel Modulation Technique Used to Obtain Output Voltage Having a Frequency Multiple of Input Voltage Frequency

This paper introduces a new modulation method that can be adopted to obtain various possible output voltages depending on the switching topology and the voltage inputs available. This method is used to obtain a sinusoidal voltage waveform with a frequency which is a multiple of the frequency of the sinusoidal input voltage. There are various applications that need a variable frequency input and a limitation is that three-phase supply is not always available. A good example to this would be single-phase induction motors. Using this method single-phase induction motors can be supplied with a variable frequency source which uses a single-phase fixed-frequency supply and so it can be used in variable speed applications. First the general idea behind this method is explained and its equations and constraint are derived. Next the technique is used to produce the desired voltage that was mentioned and the proper switching topology is explained. Then the method and its equations and constraints arc fully discussed over this particular case. Finally the simulation results are presented and analyzed

Study of Mechanical Properties and Precipitation Reactions in Low Copper Containing Al-Mg-Si Alloy

The scope of this work is to investigate the precipitation of two Al-Mg-Si alloys with and without Cu and excess Si by using the differential scanning calorimetry (DSC), transmission electron microscopic (TEM), Vickers hardness measurement and X-ray diffraction. The analysis of the DSC curves found that the excess Si accelerate the precipitation and the alloy contain the excess Si and small addition of copper has higher aging-hardness than that of free alloy (without excess Si and Cu) at the same heat treatment condition. The sufficient holding time for the precipitation of the β'' phase was estimated to be 6 hours for the alloy aged at 100°C and 10 hours for the alloy aged at 180°C. The low Copper containing Al-Mg-Si alloy gives rise to the forming a finer distribution of β (Mg2Si) precipitates which increases the hardness of the alloy. In order to know more about the precipitation reactions, concern the peaks on the DSC curve transmission electron microscopy observation were made on samples annealed at temperatures (250°C, 290°C and 400°C) just above the corresponding peaks of the three phases β'', β' and β respectively

Different diode configurations evaluation in photovoltaic arrays using binary coding method

This paper used a robust mathematical way (binary coding method) to study shadow effect in photovoltaic arrays. Binary coding method provides a way to define power generation index (PGI) as a factor which shows the performance of arrays at shadow condition. Different configurations of photovoltaic (PV) array show different behavior at shadow condition. Configurations behavior depends on modules interconnections, bypass and blocking diodes, and etc. Configuration which has better working condition should be chosen for PV array. In this paper all conventional configurations are analyzed and compared by the use of PGI value. Over currents which may create in some states of shadow is studied. Moreover, this paper deals with influence of working voltage range of inverter in maximum power point tracking. Finally, configurations are rated

A simplified skyline-based method for estimating the annual solar energy potential in urban environments

Architects, engineers and urban planners have today at their disposal several tools for simulating the energy yield of photovoltaic systems. These tools are based on mathematical models that perform repetitive calculations to determine the annual irradiation received by solar panels; hence when photovoltaic systems are installed in complex urban environments, the simulations become highly computationally demanding. Here we present a simplified and yet accurate model for the direct calculation of the annual irradiation and energy yield of photovoltaic systems in urban environments. Our model is based on the correlation between the solar radiation components and the shape of the skyline profile. We show how calculations can be simplified by quantifying the skyline using two indicators: the sky view factor and the sun coverage factor. Model performance is evaluated in different climates using measured data from different photovoltaic systems. Results indicate that the proposed model significantly reduces the required computation time while preserving a high estimation accuracy.</p

Integration of bifacial photovoltaics in agrivoltaic systems: A synergistic design approach

To safeguard future renewable energy and food supply the use of agrophotovoltaic (APV) systems was investigated, which enable simultaneous production under the same piece of land. As conventional photovoltaic (PV) array topologies lead to unfavourable conditions for crop growth, the application of APV is limited to areas with high solar insolation. By optimizing the APV array’s design, compatibility with various climates and crop species can be attained. Therefore, the aim of this research was to establish a multi-scale modelling approach and determine the optimal topology for a medium-to-large-scale fixed bifacial APV array. Three main topologies were analyzed under the climate of Boston, USA: S-N facing, E-W wings, and E-W vertical. For each topology, respectively, specific yield was amplified by 39%, 18%, and 13% in comparison to a conventional monofacial ground mounted PV array. E-W vertical is more appropriate for permanent crop species, while S-N facing necessitates the cultivation of shade tolerant crops during summer as electricity generation is prioritized. The E-W wings APV topology combines the best of both; light is distributed homogeneously, and crops are effectively shaded at noon. To promote the growth rate of blueberries under shade, customized bifacial modules were integrated (arranged as the E-W wings). Land productivity enhanced by 50%, whereas electrical AC yield reduced by 33% relative to the conventional and separate production. Through this holistic approach, it is possible to achieve a comprehensive understanding of the limitations and potential synergies associated with the dual use of land; ultimately, encouraging the transition of the agricultural sector into sustainability.Photovoltaic Materials and Device

Photovoltatronics: Intelligent PV-based devices for energy and information applications

At present, electrification and digitalization are two significant trends in the energy sector. Large-scale introduction of variable renewable energy sources, energy storage and power-electronics components, all based on direct current (DC), is fundamentally changing the electrical energy system of today that is based on alternating current (AC). This trend leads to a complex hybrid AC/DC power system with the extensive deployment of information and communication technologies (ICT) to keep the system stable and reliable. Photovoltaics (PV) is a technology that will play an essential role in local generation of clean electricity in expanding urban areas. To take full advantage of PV in the urban environment, PV technology must become intelligent. In this article, we identify, describe, and label a new research field that deals with intelligent PV and its application in components with multiple functionalities. We denote this field photovoltatronics. We review photovoltatronics research areas and introduce new directions for each area. Photovoltatronics brings together disciplines of energy and informatics. Since photons and electrons are carriers of both energy and information, photovoltatronics is the field that designs and delivers autonomous devices for electricity generation and information communication. It introduces a pathway from harvesting energy of photons (h?) to creating bits of information (01) through the energy of photo-generated electrons (eV). We show that ~10 keV energy is at least needed for transceiving one bit of information in the energy-information chain of the photovoltatronics, while the ultimate efficiency of the chain can reach up to 33.4%. We show that the number of publications related to photovoltatronics is exponentially increasing and the publication rate of combined research areas has been doubled in the present decade and reached 3.4% as a clear sign of its emergence.Photovoltaic Materials and DevicesElectrical Sustainable Energ