This paper talks about Sb2S3, which is binary semiconducting compound being used as light harvesting material for solar cell applications these days. It has high light absorption coefficient, excellent air and moisture stability. Sb2S3 can serve as sole light absorption material or top cell light absorption material in solar cells coupling with low band gap solar cells for obtaining more high power conversion efficiency (PCE).The composition engineering is used to determine the final PCE in a complete device which is dependent on photovoltaic properties of Sb2S3 solar cells. This composition does not have much great influence on the crystal structure, optical band and film formability, while the carrier concentration and transport dynamics are considerably changed. Therefore composition of ratio enables significant improvement in the device performance. The paper clearly focuses on the building solar cells that are used to give power supply to the bulding system hence it is called building integrated solar thermal system.
At first the types of building solar systems are classified to give an idea about the terminology. Secondly the paper focused on the cost effective ways to transform the energy.The paper focuse on transport of energy to storage unit so that it could be used a the time of low sunlight. Types of fluid used by solar plants are synthetic oil,steam or molten salts.the goal is that by increasing the thermal temperature of the fluid there could be more efficiency. There are two ways to heat the fluid that are either the particles are directly heated or by the heat transfe wall that is further transmiting their energy via a heat exchanger to the working fluid (steam or gas) to run a turbine.
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Test like falling-particle cavity receiver prototype ,the Small Particle Heat Exchanger Receiver (SPHER) concept was tested using a solar simulator, concept of upward fluidized particle-intube (or upward dense particle suspension) (Flamant and Hemati, 2010) to overcome the HTF temperature limitation were carried out. upward flowing dense particle suspension (UDPS) was a success and it could be well setup and perform for temperature upto 700 °C
The main drawback was that there were only few particles were accepting the flux density at receiver with good material property.so we have to increase the heat transfer coefficient for the particles. Due to low cost of molten Solar salts they are used as heat transfer fluid and are more common in today’s market more than 70% of new plants use these types of salts as fluids whereas using these have its own disadvantages as low temperature range,corrosion on rods etc.but it reduces investment cost and increases overall efficiency. This paper discussabout the Photovoltaic (PV) configuring it as a competitive technological alternative to convert solar radiation into electricity, and provides a fundamental contribution to the transition from traditional fossil fuels to renewable energy based economies.It discusses the economic sustainability of photovoltaics. Si-crystalline (mono or poly) panels have been dominating the PV market over the past decades. In order to reduce the panel production costs,Si-amorphous, CdTe and CIGS thin film, organic and hybrid cells are being developed as an alternative photo voltaic technologies. The average lifetime of a PV panel is, irrespective of the consideredtechnology, around 25 years (Paiano, 2015). There is an estimation of a dramatic increase in the annual flux of end-of-life PV panelsaround 2025.
Economic sustainability is largely dependent on the fraction and the quality of materials that can be recovered by the proposed recycling processes. In addition to this view, assessing the economic sustainability of the proposed recycling processes is however a complex task owing the modifications of the PV panel compositions that are continuously and rapidly introduced even for the same PV technology. Variations in the production techniques have led, for example, to a progressive decrease in the PV panel metal content, which ultimately caused a reduction into the value of recovered materials. Similarly, variations in the cost and availability of the primary resources are used to produce PV panels which can dramatically influence theeconomic feasibility of the proposed recycling processes.
Preparation of Sb2S3 thin film –The thin films of Sb2S3 were deposited on TiO2 coated F:SnO2 (FTO) glass by thermal evaporation under high vacuum. The deposition rate of S or Sb powder and Sb2S3 powder each was raised to 1 and 3–4 nm/s before opening of the flapper. Thickness of the film was controlled by film thickness gauge. The deposition was carried out under room temperature. The as-deposited film was immediately transferred into N2 glove box and annealed at hot plate at 300 C for 2 min.
Device fabrication- Etched FTO glass was cleaned by IPA, acetone and de-ioned water and alcohol, treated by UV irradiation before use. The compact TiO2 layer was deposited onto cleaned FTO by spin-coating a mixture solution of titanium isopropoxide, ethanol, and HCl method followed by annealing at 550 C for 60 min in air. After the deposition of Sb2S3, Spiro-OMeTAD was spin-coated and baked at 100 C for 10 min. Finally, Au counter electrode was deposited by a thermal evaporator under pressure.
Characterizations and measurements –Also discusses the crystallinity of samples that were investigated by X-ray diffraction (XRD) using a Bruker Advance D8 diffractometer equipped with graphite-monochromatized Cu Ka radiation, the surface and cross-section morphologies of the Sb2S3 thin films were characterized by field emission scanning electron microscope and UV–vis spectroscopy was characterized by an UV–vis-NIR 3600 spectrometer. The X-ray photoelectron spectroscopy measurement was characterized by Escalab 250.
The particles choosen were olivine because of their high thermal resistance without risk of sintering at high temperature.After that the solar receiver is tubuar in shape. The particles were fed to the dispenser fluidized bed ,cold storage tank, rotary valve that controlled the particle mass flow rate. The particles were fluidized in the dispenser, the fluidized particles flew upward in the 1m-long absorber tube. Temperature and pressure sensors were also set up like thermocouples and pressure guage so as to measure te maximum temperature and flowrate of particles.
Air was injected homogenously in the dispenser to fluidise the particles.Flow rates were calculated and controlled by pressure and tuning. For this the experimental conditions were necessary so the duration depends upon the time taken to reach the thermal steady state.so 21 days of solar experiment were done for 60 operations. Thermocouple measured the several heights of wall surface temperature i.e the highest temperature of the zone.the front wall temperature eis related to solar flux density.for low flux the temperature was 500 c,for medium flux the temperature ereaches 800 c.and for higher solar flux it gets upto 930 c. Particle temperature as observed gets upto 400-500 c. The paper mainly involves the discussion of the composition controlled synthesis of Sb2S3 films and the results before, after and during its composition.
The composition follows preparation of Sb2S3 thin film, device fabrication and characteristics and measurement Here, the pristine Sb2S3, sulfur doped Sb2S3 and antimony doped Sb2S3 are denoted as P-Sb2S3, S-Sb2S3 and Sb-Sb2S3, respectively. The phase formation and crystalinity of as-deposited Sb2S3 films were firstly characterized by XRD. P-Sb2S3 exhibits diffractions, which are crystal planes of orthorhombic Sb2S3 phase. With coevaporation of S and Sb, the XRD characterizations display identical patters to that of P-Sb2S3, no impurity phases such as sulfur and antimony are identified. This observation indicates that sulfur and antimony are entered into the crystal lattice. The tunability allows fundamental understanding as well as performance enhancement in Sb2S3 solar cells. Also tells that Sb2S3 film with S- or Sb-rich did not change the band gap of antimony sulfide films.
It is given in the paper that ther ea re two types of collectors installed on the buildings .the first one is with rear ventilation, the air gap between the collector was provided so that the collector is fully surrounded by ambient temperature whereas there is a second type of setup in which the collector is installed such that there is no rear ventilation so also there is room temperature which is affects the performance. The paper also focuses on solar envelopes.they are a much obvious and more general techniques introduced in current scenario of India. Here it is given about the German agenda to how to cut cost in coming decades and to rely more on solar energy. Here they assumed the total cost without the solar system supply that the annual income would be a way more lower than the total cost of electricity and heat combined.
The entire energy system is made up such including the transforming cost so as to cope up with rising prices of fossils and co2 emissions still the renewable energy cost are low.
Bergmann and weib(2002) investigated 14 BIST installations and concluded that stagnation is the way to reach peak temperature(195 c) for the heat transfer fluid, heat materials should be used and thermal expansions should also get considered. One of the important suggestion was that at the time of installation without rear ventilation the casing of the collector to be open so that there are no moisture problems generated.
The article (munari probst and roecker,2007) gave the four ideas about the positioning of collector should be such that it get compatible with the building architecture. The size of the solar thermal element (collector) should be such that it should exactly fit in the building envelope and shape of it that further developed to be “solar energy and architecture”. Economic barrier is also discussed in the paper as the major barrier is that customers were firstly not aware of this BIST technology and even if they were educated about this they were hesitating of the extra cost of installing without knowing the profits of its installation.
Subcomponents for the BIST system are also discussed like for glazed collectors (glassed texture) ,screen printing, sand blasting or etching could be used. There are certain ways which are suggested to stick the sheet with the absorber tube. Welding like ultrasonic welding are also used. Adhesives bonded sheets could also be used. Types of collectors like Opaque or unglazed and glazed collectors also have various properties as opaque collectors can’t reach upto that temperature levels that glazed collectors do because they differ in heat transfer medium.
Then came the polymers collectors that embodies less grey energy comparatively, they also had transparent glass tiles which were curved. there came the semi transparent BIST products also came so that the enterior and exteriors should be made visible from the building.
It could give many benefits including cost cutting which are as follows:- Domestic water heating, Space heating, cooling, dehumidification, solar control (reduce overheating of building)etc. The energy on the other hand are calculated with the help of g and u. I.e g is total solar energy transmittance and u is over thermal transittance of the building.G value is not constant in general because the energy of solar interior flux depend upon the working of collector and the iirradiance.
The measurement firstly follows the optical measurement than it is calorified and then the thermal performance is measured through this. The component of BIST includes glass, absorber, bist element, insulation, back cover, diffusion barrier, heat flow pipes, mountings. The paper also deals with the economical aspects of the system as from start to end i.e in how much investment the plant get setup and installations after that the maintenance.
Case study about different types of house and there cost estimations are given. Challenges faced by this system were challenge in affects i.e. the performance of the system is difficult to quantify also there is a challenge about the future aspects of the tech as it will grow in future or not or wether it would develop or not. About sodium the advantage is that it has high temperature range in liquid state.it is chemically stable and can be operated at vapour state too upto 800°C. and also sodium does not show corrosion problems below the boiling point.Thermal conductivity for the sodium is also appericiable.The main problem of sodium is its reactivity with water and oxygen which could create explosion and fires.
Various measures were taken to resolve this problem and various guidelines were also provided but in some cases these guildines didn’t worked and created major fires in history.sump tanks and argon were the solutions and were made a art of safety system.
The comparision for both solar salt and sodium receivers for the plant were given which included extra Em pump and a sump tank for sodium so as to play a safety role in it and for the thermal energy storage molten salt use two tank storage system but instead of that one could get more economic.
Cost evaluation methodology states that it majorly depends on the receiver design and its size depends upon accuracy,power, parasitics and cost.by reducing the absorber area the cot reduses and also efficiency increases but the same time it increases spilage losses and other losses too which eventually increase the cost.for this the ideal aperture size is to be selected. Annual yield is also calculated .for the cost function the heliostat field cost is calculated and also the cost of two tank system is also calculated.
The paper can be concluded with the co-evaporation of element sulfur or antimony with Sb2S3 to manipulate the composition of Sb2S3 films. The structural analysis shows the incorporation of sulfur or antimony into the crystal lattice upon postannealing. With this method, sulfur- or antimony-rich Sb2S3 films are obtained. This elemental manipulation does not notably affect the band gap, morphology and crystallinity of the final films, while the carrier concentration and charge transport properties are essentially altered. Ultimately, sulfur-rich Sb2S3 film based device shows high carrier concentration, reduced recombination probability when compared with pristine and antimony-rich Sb2S3 based devices. we have discussed about the building integrated solar system .its definition was explained. its components were discussed and also we got aware that it is not that difficult to install BIST in the buildings looking at its future aspects.
Experiment performed one 1 meter tube solar absorber to improve the heat transmission between fluid suspension and absorber wall. 3 solar flux were analysed with different ranges of mass density to check real operating condition. Tube surface temperature distribution has been measured as a function of the solar flux density and the particle mass flow rate. Particles were heated from 400 and140°C. Under low solar flux the power extracted by the particle suspension reaches 17.8kW and 32kW under high incident solar flux. The typical thermal efficiency of this lab-scale solar receiver is 75%. There is a need to get rid of the PV cell recycling process as there is a estimation that I future there would be an extensive use of solar power so we are in need to get better and better processes.
So in future if these are not treated well can cause harmful defects also and also could create valuable material loss. The paper concludes rapid increase in the photovoltaic power installed worldwide is causing and over the next few decades, a dramatic increase in the volume of end-of-life photovoltaic panels. The improper disposal of these waste fluxes are and will cause harmful effects to human health and to economy of the manufacture sector by the dispersion of toxic elements and loss of valuable material resources including rare metals, respectively. The processes that consider the recycling of thin film panels are economically more preferred due to the content of high value materials recovered. When treated using Mechanical processes, they are inexpensive, but they cannot attain the recovery of high value materials. Thermal processes rely on the pyrolysis of plastic panel fraction and it is characterized by high energy consumption. They do not generate further waste but produce toxic gas emissions, like fluorine gas. Chemical processes are mainly aimed for the recovery of the module metal fraction and use solvents and other reagents. These processes discussed require larger costs but the purity of the final output materials, especially high value metals, are higher than those obtained from mechanical processes. The energy expenditure in a recycling process is less than that spent in the manufacture of a new panel. Thus, the research on PVP recovery techniques is in constant development, emphasizing on ideal process that results in the treatment of all typologies, since other technologies tend to emerge and share the market with Si technology.
Therefore paper shows us our major concern to be acted upon is the development of processes allowing for the regeneration of the employed reactants, which will considerably reduce the environmental impact and the processing costs.
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