One approach to enable the use of cheaper materials in solar cells involves orthogonalization of the directions of light absorption and charge-carrier collection. For example, in an oriented array of semiconductor nanorods having radial p-n junctions, the light can be absorbed along the long axis of the rod, whereas the charge carriers can diffuse a short distance radially to the junction (Figure 2.1). In this design, devices exhibiting high energy-conversion efficiencies can in principle be produced from an absorber material that has a much smaller diffusion length than that needed for high efficiency in a planar solar cell configuration. Specifically, an analytical study of the governing generation, transport, and recombination equations has shown that high efficiencies can be maintained in oriented rod array solar cells provided that the diffusion length in the material is comparable to the radius of the rod. 1 Materials with diffusion
The test was made well. After the test the theory about installation was discussed, every tool needed was explained. After the explanation a solar system was installed. Everybody installed a little thing and together the trainees installed the total system. It was a very nice experience for everybody. Before installing the battery, the trainees measured the voltage over the battery, the battery was almost empty. When the system was installed completely, a red LED in the charge controller was emitting light and the charge controller was bleeping. After a few seconds the installed lamp was not emitting light any longer. The system was moved outside and positioned in the sun. The yellow LED in the charge controller was emitting light now. After a few hours the charge controller showed that the battery was charged half and the students checked this by measuring the voltage over the battery. After this the system was put inside the classroom en the day was finished. Everybody liked seeing a real solar system and working with it.
famous as well as most widely researched and commercialised to date. Unlike the other solarenergy conversion technologies, PV technology has provided power for various levels of application ranging from low power applications in the order of 1.0 W as in calculators and wrist watches, to Megawatt applications such as in power stations [72 - 74]. The basic principle of operation of PV solarenergy conversion is based on the ability of photons from the solar radiation to break bonds in a photovoltaic (photo active) material in order to create electron-hole pairs which can then be separated by a built-in electric field (in a fully fabricated photovoltaic device) and collected in an external circuit (before they are recombined) to produce electricity . The fully fabricated photovoltaic device is a solar cell. The photovoltaic solar cell will be discussed in full in chapter 2. Nevertheless, various techniques have been employed to increase the conversion efficiency of PV solar cells. These include the use of solar concentrators  and multi-junction tandem approach . Various photovoltaic materials used to date in the fabrication of solar cells include organic (such as semiconducting polymers) and inorganic semiconductor materials. The conversion efficiency of a photovoltaic solar cell depends on a number of factors ranging from the device architecture to the energy bandgaps of the semiconducting materials used as well as the chemical nature of these materials. Further details on the efficiencies of different types of solar cells will be presented in chapter 2. Figure 1.9 shows the schematic of a typical superstrate photovoltaic solar cell structure.
The solar collector is a dual function apartment, which consists of a solarenergy collector and an imbedded pebble bed heat storage unit. The solarenergy collector / heat storage unit (A) is a flat –plate solarenergy collector that collects and stores solarenergy. It has internal dimensions measuring 110cm x 65 cm x 20cm giving radiation absorption surface area of 0.715m 2 and 0.143m 3 volume. The wall of the collector (a) is constructed of 2 cm wooden materials, which serves as an insulating material. Three quarters (3/4) of the volume is filled with uniformly sized pebbles, which constitutes the pebble bed (b). The pebbles on the top surface of the bed are painted black to form the solarenergy absorber. This is covered with transparent glass-perspex cover (c) at a 2 cm distance above the solar absorbing surface. The pebbles store solarenergy during the sunny hours of the day, which could be used during off-sunshine hours such as night and cloudy periods of the day. This provision ensures that drying process takes place all the day round. The solar collector is inclined at 22 0 to horizontal and oriented towards south for all year round solarenergy collection. Two openings (d) and (e) for fresh air entrance are located at the lower end of the solar collector while another opening (g) at the upper end allows exit of hot air form the collector into the drying chamber. The lower air openings are provided with shutters either to close or
Abstract Solar powered steam generation is an emerging area in the ﬁ eld of energy harvest and sustainable technologies. The nano-structured photothermal materials are able to harvest energy from the full solar spectrum and convert it to heat with high ef ﬁ ciency. Moreover, the materials and structures for heat management as well as the mass transportation are also brought to the forefront. Several groups have reported their materials and structures as solutions for high performance devices, a few creatively coupled other physical ﬁ elds with solarenergy to achieve even better results. This paper provides a systematic review on the recent developments in photothermal nanomaterial discovery, material selection, structural design and mass/heat management, as well as their applications in seawater desalination and fresh water production from waste water with free solarenergy. It also discusses current technical challenges and likely future developments. This article will help to stimulate novel ideas and new designs for the photothermal materials, towards ef ﬁ cient, low cost practical solar-driven clean water production.
Solar reflectance, or albedo is the fraction of the incident solarenergy that is reflected by the surface material. Solarenergy consists of a spectrum of wavelengths, including ultraviolet, visible, and infrared light. The solarenergy distribution as a function of wavelength is shown in Figure-2. Surface materials that reflect solarenergy and all over wavelengths (i.e., that have a higher solar reflectance of surface material), will have better performance in reducing roof solar heat gain. Color is a good indicator of solar reflectance only in the visible light range, with reflectance typically increasing from a dark-colored to a light-colored surface. For example, traditional dark-colored roofing materials have a solar reflectance of about 0.04 to 0.18, whereas light-colored roof surfaces have a reflectivity of 0.70 or higher “Cool color” technologies can increase the solar reflectance of roofing materials in the infrared range through the application of a special coating. In this application, the roof has the same visual appearance, but is much cooler. In this example, the solar reflectance in the visible portion of the spectrum is the same for both products; however, the product employing “cool color” technology remains cooler by having much higher reflectance in the IR range.
The first reported application of PCM was back in 1940s.The main attracting feature of the PCM is that they have a greater storage capacity than that of conventional materials as they can store heat energy in a latent form. When the temperature rises, the chemical bonds break as there is a change in phase from solid to liquid. The PCM absorbs heat as the phase change process is endothermic and when the atmosphere cools down it return back to its solid phase releasing the stored heat. GlassX is an example of such PCM facades and it consists of a PCM in its core which is made up of Calcium chloride hexahydrate (CaCl2 6H2O) which is a non-toxic salt, with a melting point at room temperature. It can provide a thermal mass equivalent to that of 16‖ of concrete. The most complete model, GlassX crystal, is made up of multiple low-emissivity glass in one of whose chambers a prismatic panel is inserted that reflects solar radiation in summer (solar height> 40º) and transmits it when the sun falls below 35º in winter. The main function is carried out by a polycarbonate panel inserted in another chamber and filled with a phase change material (MCF) that, when the temperature rises above 24 or 28 ºC, melts over eight hours , absorbing up to 1185 W · h / m². When the temperature drops, at night or on cold days, the MCF crystallizes, releasing heat and therefore reducing the thermal jump. Depending on the model chosen, the U value varies between 1.1 and 0.49 W / m²K. It is marketed in a maximum format of 200 x 300 cm and 79 mm thick . Facades made of this material do both the function of absorbing the solarenergy and protecting it as well. A layer of salt crystals on the surface will help absorb the heat and the prismatic glass allows the radiation to pass only at the lowest angle of radiation. During summers, the solar radiation is reflected by a prismatic outer layer when the sun is at an angle higher than 40 degree. During winters, when the sun is at a lower angle lesser than 35 degrees the prismatic layer allows more solar gain. One of the recent examples is GlassX as Phase Change Materials Vocational school in Freiburg, Switzerland (Figure 12).
The main aim of this project is to utilize the application of the Arduino board to control the intensity of street light. As the traffic decreases slowly during late-night hours, the intensity gets reduced progressively till morning to save energy and so, the street lights switch on at the dusk and then switch off at the dawn, automatically. The process repeats every day. White Light Emitting Diodes (LED) replaces conventional HID lamps in street lighting system to include dimming feature. The intensity is not possible to be controlled by the high intensity discharge (HID) lamp which is generally used in urban street lights. LED lights are the future of lighting, because of their low energy consumption and long life. LED lights are fast replacing conventional lights because intensity control is possible by the pulse width modulation. This proposed system uses an Arduino board and a rectified-power supply. String of LED are interfaced to the Arduino board with a MOSFET device.The intensity control of the LED light is possible by varying
The paper examined the role of heat index on the thermal comfort and health of building occupants. In addition, perspectives on the potential health related illnesses that can potentially arise from soaring global temperatures, global warming and climate change were also presented. Lastly, the paper briefly highlighted some potential low cost strategies and carbon technologies for mitigating the effects of climate change. The findings showed that the application of Low Carbon Materials (LCM), Building Solar Shading Strategies (BSSS), Renewable Energy Technologies (RET) and Sustainable Design Practices (SDP) can potential address the challenges of global rising temperatures and climate change. The defined strategies can also to improve, preserve and protect human health, safety and thermal comfort of building occupants against the adverse effects rising global temperatures and climate change.
2 SOLAR COLLECTOR - THE SOLAR ROOF The solar roof consists of a random number of solarenergy collectors linked into a whole and installed on the roof of a building. Since all connecting tubes are inside the solar roof, such a design also represents a good aesthetic so lution. However, besides a pleasant appearance, we also wanted to assure better efficiency of operation.
During operation, the efficiency of solar cells is reduced by the dissipation of power across internal resistances. These parasitic resistances can be modeled as a parallel shunt resistance (R SH ) and series resistance (R S ), as depicted in
Various different types of nanofluids having different base fluids like water, ethylene glycol and therminol VP-1 and having different nanomaterials consisting of gold, silver, copper, aluminium and their corresponding oxides has been used as working fluids for the solar collectors . Nanofluids have got remarkable features as they enhance the system efficiency due to their better thermal properties like better thermal conductivity and heat transfer coefficient  and also they directly absorb the incident solar radiation, thereby avoiding intermediate stage of heat transfer and so, associated heat loses are avoided  Recently, various researches have taken place with usage of nanofluid as main working fluid in solar collector. Tyagi et al.  conducted a theoretical investigation of flat plate solar collector using Al-H 2 O
One of the major advantages of hydroelectricity is the elimination of fuel. Because there is no fuel combustion, there is little air pollution in comparison with fossil fuel plants and limited thermal pollution compared with nuclear plants. Hydroelectric plants also tend to have longer economic lives than fuel-fired power generation, with some plants now in service which were built 50–100 years ago. Operating labour cost is also usually low, as plants are automated and need few personnel on site during normal operation. The sale of electricity from the station may cover the construction costs after 5–8 years of full operation. Hydroelectric usually refers to large-scale hydroelectric dams. Micro hydro systems typically produce up to 100 kW of power. Hydro systems without dam derive kinetic energy from rivers and oceans. Ocean energy includes marine current power, ocean thermal energy conversion, and tidal power. The present installed capacity as on September 30, 2013 is approximately 39,788.40 MW which is 17.39% of total electricity generation in India.  The public sector has a predominant share of 97% in this sector.  National Hydroelectric Power Corporation (NHPC), Northeast Electric Power Company (NEEPCO), Satluj Jal Vidyut Nigam (SJVNL), THDC, NTPC-Hydro are a few public sector companies engaged in development of Hydroelectric Power in India.
Landscaping provides a buffer against heat, sun, noise, traffic and airflow. It is also effective in diverting the flow of air or the exchange of heat in a passive solar project. Deciduous trees, such as amaltas, champa and similar varieties, provide shade in summer and sunlight in winter when the leaves fall. Therefore, planting such trees to the west and southwest of a building is a natural solar passive strategy. Evergreens provide shade and wind control throughout the year. They are better located to the north and north-west of a building. Natural cooling without air conditioning can also be improved by planting trees to channel summer breezes into tropical climates. Hard surfaces and dark- colored floors, such as concrete sidewalks or concrete cement roads around a house, should be avoided, as they can increase the temperature of the environment. Increasing the temperature would cause thermal disturbances inside the house and increase the air conditioning bills. Instead, soft surfaces such as organic flooring or vegetated areas should be used.
Omitted variable bias is another potential source of endogeneity. For instance, differences in capacity factors and technology costs between countries could cause differences in energy output. Not controlling for specific technology differences is a reasonable approach given that differences in capital expenditure are difficult to determine at a national level (Ondraczek et al. 2015). Another group of variables that could lead to omitted variable bias is fossil fuel reserves, as Burke (2010; 2013) finds that fossil fuel reserves are important for energy and electricity mix. Countries could favour use of fossil fuels as substitutes to renewable energy when they have large domestic reserves of fossil fuels, but the correlations between fossil fuel reserves and modern renewable energy use are quite low in Table A3.2. There could also be channels of government policy effort that are not measured by the policy variables in this paper. While the EU policy support variable used in this paper may not be measured perfectly, it is intended to be comprehensive. To further address the issue of potentially missing policy variables, I note that I control for government effectiveness and the cost of capital to incorporate views on investment attractiveness differences across countries.
Tabatabaei  Firstly, the way of using sustainable desert energy in buildings and how to use solarenergy and the way of decreasing infiltration inflow weather from outdoor and absorption of the heat of solarenergy; Secondly, how to use air condition and make cold weather with using solar power to have comfortable place in desert buildings. Finally, using traditional wind catcher illustrated and suggested similar system for new tall tower and buildings that can be used in other hot climates. Vaghefpour, zabeh  Discuss role of cooperation in creating opportunities for using rich renewable energy sources and also their potential role for entrepreneurship and employment in Iran. The presence of constant, sustainable and economical energy is an essential basis for any economical and social development while it can upgrade life qualities. Iran has a considerable amount of natural resources for modernizing its energy supply and being transited to a sustainable energy system as it has countless opportunities for using rich renewable energy sources. On the other hand, cooperation have been considered as a strategic way to create job opportunities as they are strong organizations which can encounter economical and social side-affects caused by quick moderating procedures in structural programs. Results show convergence between renewable sources development and Iran's economical development through taking a frugal approach in expenses, creating new job opportunities and entrepreneurship in renewable energies. Zahedi  Present the results of a study conducted to examine the potential role and potential benefits of energy storage integrated into intermittent sources. Using energy storage will provide an opportunity to create a sustainable power supply, and to make
The prime requirement to do any work is Energy. Till late 90’s the world had been using conventional or non- renewable resource like coal, petroleum, etc., to fulfill their energy needs. But these resources posed a serious threat on the environment. The second drawback of conventional resources is that they may get extinct in a short time. So the only choice we are left with is to find an alternative. The substitution to the non-renewable resources is the promotion of renewable resources like solarenergy. Solarenergy is radiant light and heat from the Sun that is harnessed using a range of ever-evolving technologies such as solar heating, photovoltaic cells, solar thermal energy, and artificial photosynthesis. Solar techniques used now a day’s includes the use of photovoltaic systems, concentrated solar power and solar water heating to harness the energy of sunlight .Solarenergy is an important renewable energy source for the country, both in the generation of PV electricity and as heat. Therefore, it is necessary to quantify the solar potential of an area, but to achieve this goal
structure design of semiconductor materials for high performance solar cells using theoretical and mathematical approaches. First and foremost, the fundamental properties and some important parameters that will perform for all related equations will be described in details. The theories of p-n junction and the related equations to draw the band diagram of semiconductor material will be presented. In addition, this paper includes the mathematical calculation that is required to obtain the characteristics of the individual semiconductor material. Secondly, the voltage current characteristics and efficiencies for different mole fractions of semiconductor is calculated and analysed. Finally, other optical properties that are associated with the basic concepts of semiconductors will be included in this paper. Therefore, the fundamental needs for high performance solar cells and some essential properties are presented for this paper development [2-7].
Abstract— Photovoltaic water pump system is easy to install and operates .solar power also reliable alternative which is being used in a wide spread of the ever so developing technology in the world. Also India is one of the sunniest countries in the world with 250-300sunny days every year. But low efficiency & non linear I-V characteristics increases their cost , so in order to meet the need for promising development ,it must be made to increase the efficiency of P-V System & to decrease the cost from the sun. So design and simulation of p- v water pumping system is done in this paper.