Do It Yourself Solar Energy

DIY Home Energy System

This ebook guide teaches you how to escape complete dependence the power grid and learn how to live mostly on your own power and make sure that you are dependent on Yourself. You will be able to slash your energy bill by over 75% and not have to depend on greedy energy companies. The largest energy corporations are a monopoly for a given area, so they do not need to care about customer service or doing right by the people they service. You will learn how to break this monopoly and depend on yourself. Make your home immune to power shortages, blackouts, and energy failures; live free of any worry that the grid will totally fail you! You will learn practical steps such as how to build your own solar panel for less than $60! Once you start relying more on solar power you will be able to easily protect your family from dangerous power outages, and live free! Read more...

DIY Home Energy System Overview

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4.9 stars out of 28 votes

Contents: Video Course
Author: Jeff Davis
Official Website: diyhomeenergy.com
Price: $47.00

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My DIY Home Energy System Review

Highly Recommended

I usually find books written on this category hard to understand and full of jargon. But the author was capable of presenting advanced techniques in an extremely easy to understand language.

This e-book served its purpose to the maximum level. I am glad that I purchased it. If you are interested in this field, this is a must have.

Point to Ponder Why arent solar power plants more popular in sunny deserted areas

One of the major advantages of solar power plants is that the energy is free. There are, however, several issues to consider that impact cost and social acceptability. The free energy from the Sun has to be collected and transformed into commercially useful energy. Solar power plants to date cover the area of several football fields and produce approximately 1 of the power associated with a fossil fuel fired power plant. This means that solar power plants will cover relatively large areas and may be considered eyesores by some people. In addition, the technology of maintaining the collectors, and collecting, transforming, and transmitting solar energy is still relatively expensive. Fanchi, 2004, Exercises 7-11 and 7-12

Shining a Light on Solar Power for Your Home

Om a pollution standpoint, solar power is the most energy-efficient invest-ent you can make, hands down. Sunshine will always be free. Solar power equipment, however, can be expensive and isn't suitable for climates that don't get enough sunshine. Government subsidies play a big role in solar power, but they vary with the political winds. The most definitive factor in determining the viability of solar power is local utility rates if yours are high, solar energy may be just what you're looking for because the financial efficiency is good. When all the factors are working for you, an investment in solar energy can be much better than an investment in the stock market. In this chapter, I cover the most popular solar investments, and I present some guidelines on when and where solar power is a worthwhile investment. For more details, consult my book Solar Power Your Home For Dummies (Wiley).

Harnessing the Sun with Solar Power

Battling the challenges to and economics of widespread solar power use Looking through present and future solar power options 7he sun sends over 35,000 times more energy to earth than humans use in all of their energy consumption endeavors. To put it another way, people use less energy in 27 years than the earth receives from the sun in a single day. That's a lot of solar energy for all practical purposes it's an infinite supply, and renewable to boot. Best of all, it's the cleanest source of energy the world has ever known. The problem, of course, is turning all those free-for-all photons into useable energy, or ordered, energy. While humankind has been inventing creative ways to do just that for thousands of years, solar still affords a very limited applicability in the grand scheme of things. Only 0.03 percent of the world's ordered energy production comes from solar, and even though the industry is growing by over 33 percent per year, there's a long road ahead.

Current and future efficiency ratings of solar panels

Overall, the typical efficiency rating for a solar panel is around 16 percent, which means that of all the sunlight energy that is collected by a PV panel, only 16 percent of that energy is available as electrical power. Because there is a maximum amount of sunlight power of around 1 kW per square meter, a square meter of PV panel can only put out around 0.18 kW. There have been increases in this value, but the costs are prohibitive. At sea level, on a clear day, around 1 kW of solar energy is incident on a one square meter surface (to put this in perspective, a pool pump uses around 1.5 kW's of power, and this is a lot of power). In the mountains, where the air is thinner, even more radiation is measured because much more of it gets through the thin atmosphere. However, as we all know, the sun's intensity varies over the course of a day, so it's of interest to calculate just how much solar radiation falls on a one square meter surface over the course of a day.

The Economics of Solar Power

Although a number of studies have shown a net positive impact of solar energy, particularly in communities dedicated to large-scale development of solar power, the most basic reality of solar power is that it is viable only in sunshine rich climates, particularly the Southwest and Pacific coastal areas. Even with government subsidies, solar is not now, nor will it likely ever be, viable in cloudy, rainy climates. However, if the price of solar decreases enough, this may change, although the vehicle of change will be investment capital, and when solar lags so far behind other alternative energy sources, investment capital also lags behind. The following sections provide you with info on the economical impacts of large-scale solar power use, including the benefits as well as the economical challenges solar power faces.

Solar Energy And The Upper Atmosphere

The sun radiates in all directions, and only a tiny fraction of its output is intercepted by the earth, 150 million kilometers away. On average, the solar power received by the earth is 340 watts per square meter of surface2 or, more concisely, 340 W m-2. It is important to be aware of what the averaging entails. First, the averaging is over the whole surface of the earth it allows for the difference between the polar regions where the sun never rises high in the sky and the tropics where the midday sun is not far from the zenith on every day of the year. Second, the 340 W The Solar Energy Budget Now consider the fate of this incoming energy. The first point to notice is that solar energy does not accumulate appreciably. The earth's net gain of solar energy over the year is close to zero, and were it not for global warming it would remain at zero, on average. If we take the long-term view, disregarding slight temporary climatic wanderings caused by atmospheric changes, it is safe to...

Energy Options Solar Energy

Renewable energy is energy obtained from sources at a rate that is less than or equal to the rate at which the source is replenished. In the case of solar energy, we can only use the energy that is provided by the Sun. Since the remaining lifetime of the Sun is measured in millions of years, many people consider solar energy an inexhaustible supply of energy. In fact, solar energy from the Sun is finite, but should be available for use by many generations of people. Solar energy is therefore considered renewable. Energy sources that are associated with solar energy, such as wind and biomass, are also considered renewable. Solar radiation may be converted to other forms of energy by several conversion processes. Thermal conversion relies on the absorption of solar energy to heat a cool surface. Biological conversion of solar energy relies on photo Solar energy is available in three forms passive, active, and electric. Passive and active solar energy are generally used for space...

Marketing solar energy systems

Market transformation for solar energy systems is gaining increasing importance as we move through the second decade of green building practice (using the formation of the USGBC in 1993 as a starting point). Recent project experience illustrates the opportunities and challenges facing marketers for solar energy products and systems in commercial and institutional projects. The US Navy in San Diego installed one of the largest systems for a commercial or institutional setting, with a nearly 1-megawatt (peak rating) system, as shown in Figure 7.3. The PV system also serves as the canopy for a carport, used for long-term parking of vehicles. Survey of solar power use When asked if they had considered using solar energy in any of their projects, 84 percent said yes, with 73 percent considering PV (including 51 percent with building-integrated PV), 57 percent solar water heating and 19 percent solar pool heating. Of these respondents, 59 percent currently had a project in design, 28...

Renewable Energy Sources Solar Energy

An enormous amount of solar energy is available and it has been used for centuries.76 Because of the history and great availability, harvesting solar energy has again attracted much attention. 77 The contiguous 48 states have a total area of 8,018,880 square kilometers (8.019xl016 cm2). As described earlier, the sun provides 8.38 Joules cm2 min. There are 525,600 minutes per year. On the average, the sun shines V2 the time. Thus, the 48 states receive 1.766x 1023 Joules per year. From the Table 2.1 the 1999 United States energy use is 1.019 x 1020 Joules per year thus, the sun provides 1,733 times more energy than we use in the United States. Calculations indicate that if we can harvest solar energy at 5 efficiency then 1.12 of the area of United States could provide all the energy we need. At first glance, 1.12 does not sound like a large area. Expressing this area in other ways provides a feel for the immense scale of the collectors needed if we are to supply all our energy needs...

Solar Energy and the Hydrogen Economy

Solar energy is a virtually inexhaustible and freely available energy source. More sunlight ( 1.2 X 105 TW) falls on the earth's surface in 1 h than is used by all human activities in 1 year globally. The sun is earth's natural power source, driving the circulation of global wind and ocean currents, the cycle of water evaporation and condensation that creates rivers and lakes, and the biological cycles of photosynthesis and life. It is however a dilute energy source (1 kW m2 at noon, Chapter 2) about 600-1000 TW strikes the earth's terrestrial surfaces at practical sites suitable for solar energy harvesting.27 Covering 0.16 of the land on earth with 10 efficient solar conversion systems would provide 20 TW of power,28 nearly twice the world's consumption rate of fossil energy and an equivalent 20,000 1-GWe nuclear fission plants. Clearly, solar energy is the largest renewable carbon-free resource amongst the other renewable energy options. Consider the total amounts possible for each...

Renewable and Solar Energy Technologies Energy and Environmental Issues

Abstract A critical need exists to investigate various renewable and solar energy technologies and examine the energy and environmental issues associated with these various technologies. The various renewable energy technologies will not be able to replace all current 102 quads (quad 1015 BTU) of U.S. energy consumption (USCB 2007). A gross estimate of land and water resources is needed, as these resources will be required to implement the various renewable energy technologies.

What Can We Learn from Photosynthesis About How to Convert Solar Energy into Fuels

Abstract We briefly review the need for construction of novel systems for the production of clean renewable fuels to replace oil and gas. Then the case is made that if it will be possible to gain a sufficient understanding of photosynthesis that it should be possible to use this information to produce artificial leaves. These artificial leaves will be designed to convert solar energy into dense portable fuel. Currently in the developed world we get our energy mainly from fossil fuels. In fact approximately 70-80 of our current energy needs are met by burning coal, oil and gas. Unfortunately oil and gas supplies are predicted to be largely exhausted by the end of this century. Also we have a major problem caused by the increasing rates at which we currently consume fossil fuels, namely global warming caused by elevated levels of CO2 in the atmosphere. As a result of these two imperatives there is an urgent need to develop new, clean, scalable, and renewable sources of fuels. Providing...

The promise of solar energy

Solar energy is the main renewable energy resource throughout the world. Other renewable energy sources, e.g. biomass energy and wind energy, are derived directly from it. It is an abundant energy source. Our planet receives from the sun the equivalent of 15 000 times the energy consumed in the world, but this energy is diffuse and intermittent. Solar energy can be captured as either heat or electricity using the photovoltaic effect. There is considerable scope for the development of low-temperature thermal solar energy in the short term. Heat is supplied by solar sensors consisting of a black absorbent surface which transfers the heat to a heat exchange fluid, generally a mixture of water and glycol to prevent the possibility of freezing. A glazed surface is fitted over the absorbent surface to block the infrared radiation re-emitted. In the housing sector, thermal solar energy is used mainly to provide sanitary hot water. It may also be used to cater for a certain proportion of...

Modelling the Earths solar energy balance

The Earth and all its surface ecosystems rely on energy from the sun. Much of this energy for atmospheric motions comes indirectly through radiative, sensible and latent heat transfers from the Earth's surface. As noted above the mixture of greenhouse gases that makes up the Earth's atmosphere is, therefore, central to our understanding of short-term climatic change. This solar derived energy drives the biogeochemical cycles such as the carbon, nitrogen and hydrological cycles. Solar energy also provides one of the vital inputs to the photosynthetic process. Without the inputs of solar energy life as we know it would not exist on planet Earth. The solar energy flux just above the Earth's atmosphere is estimated as 1,372 W m2 where 1 Watt 1 Joule second. This energy flow varies because of solar activity (sun spots), the Earth's distance from the sun and other variables. Nevertheless, despite these changes it is convenient to represent this input of energy as the solar constant In 24...

Solar Energy Photovoltaic and Thermal

The Sun is an enormous, effective, and far-away (some 150 million km from Earth) nuclear fusion reactor that can supply the Earth with energy now, and for several billions of years to come. Sunlight, or solar energy, emitted from the Sun is the most abundant energy source. At any given time, sunshine delivers to Earth as light and heat about 10 000 times more energy than the entire world is consuming. Solar radiation, before entering the Earth's atmosphere, has a power density of 1370 W m-2 4 . Of all the sunlight that passes through the atmosphere annually, only about half reaches the Earth's surface the other half is scattered or reflected back to space by clouds and the atmosphere, or absorbed by atmospheric gases such as CO2 and water vapor, the atmosphere, and clouds. As 71 of our planet is covered with water, most of that energy that makes it to the surface is absorbed by the oceans. On a clear day, the radiation received on the Earth's surface around noon is about 1000 W m-2 5...

Point to Ponder Can distributed generation increase the usefulness of wind and solar energy

We can use sunlight 24 hours per day if we can collect sunlight at different locations around the globe. Similarly, the wind does not usually blow all the time at a particular location, but wind is always blowing somewhere. Distributed generation can be used to harvest both wind energy and solar energy. Improved power distribution and transmission systems could be used to produce energy from wind and sunshine in different parts of the world and transmit it to places where it is needed. A global energy distribution system would have to be developed and maintained to achieve this capability.

Ga applications in solar energy systems

Genetic algorithms were used by the author in a number of optimization problems the optimal design of flat-plate solar collectors (Kalogirou, 2003c), predicting the optimal sizing coefficient of photovoltaic supply systems (Mellit and Kalogirou, 2006a), and the optimum selection of the fenestration openings in buildings (Kalogirou, 2007). They have also been used to optimize solar energy systems, in combination with TRNSYS and ANNs (Kalogirou, 2004a). In this, the system is modeled using the TRNSYS computer program and the climatic conditions of Cyprus. An artificial neural network was trained, using the results of a small number of TRNSYS simulations, to learn the correlation of collector area and storage tank size on the auxiliary energy required by the system, from which the life cycle savings can be estimated. Subsequently, a genetic algorithm was employed to estimate the optimum size of these two parameters, for maximizing life cycle savings thus, the design time is reduced...

Source of Solar Energy

Solar energy is energy emitted by a star. Figure 4-1 shows the anatomy of a star. Energy emitted by a star is generated by nuclear fusion. The fusion process occurs in the core, or center, of the star. Energy released by the fusion process propagates away from the core by radiating from one atom to another in the radiation zone of the star. As the energy moves away from the core and passes through the radiation zone, it reaches the part of the star where energy continues its journey towards the surface of the star as heat associated with thermal gradients. This part of the star is called the convection zone. The surface of the star, called the photosphere, emits light in the visible part of the electromagnetic spectrum. The star is engulfed in a stellar atmosphere called the chromosphere. The chromosphere is a layer of hot gases surrounding the photosphere.

The dollars and sense of solar power

As you can see from this list, not all of the economic benefits of solar power can be enumerated in monetary terms you can't put a price on good sense With solar energy, local jobs are created, and the jobs are stable and sustainable and skilled, meaning high pay and good benefits. Yet, despite these positives, the economics of solar power are not as good as for conventional energy sources (combustion sources) upfront investment costs are high payback may take a long time and the investment is illiquid and fixed. Most people do not want, or cannot, lay out a big investment solely for the purpose of rationalizing their energy consumption.

Solar Power Supply Chain

Was soaring, the companies in the microchip supply chain tended to periodically overexpand, causing a pattern of booms and busts in which silicon prices would spike and then plunge, taking the earnings and share prices of the various players along for the ride. In this decade, the solar power boom caused by German and Japanese subsidies amplified the wave, sending silicon demand far beyond suppliers' capacity. The shortage caused solar-grade silicon prices to soar, which sent the profits of the silicon makers through the roof. This in turn caused everyone in the business to add capacity, and now a glut is projected for the final two years of the decade. Solar Cell Machinery Turning silicon into solar cells is a lot like turning silicon into microchips, so for microchip equipment makers, solar is a natural growth path. California-based Applied Materials, for instance, makes equipment that deposits thin layers of various materials onto microchip wafers and flat-panel display screens....

Solar heaters solar photovoltaics and concentrating solar power

My guess is that in many regions, the best solar technology for electricity production will be the concentrating solar power that we discussed on pages 178 and 236. On those pages we already established that one billion people in Europe and North Africa could be sustained by country-sized solar power facilities in deserts near the Mediterranean and that half a billion in North America could be sustained by Arizona-sized facilities in the deserts of the USA and Mexico. I'll leave it as an exercise for the reader to identify appropriate deserts to help out the other 4.5 billion people in the world.

Nuclear Hydro Wind Geothermal And Solar Power

Nuclear, hydroelectric, wind, geothermal, and solar power have all been offered as solutions to the energy problem. These all have various issues associated with them. However, the bottom line is that discussion of these technologies misses the point. It is true that, to the extent they can be done economically, these technologies can reduce greenhouse gas emissions by replacing coal or natural gas for electricity generation. But the central issue of energy independence is not electricity. The United States has plenty of coal, and if necessary it could generate all of its electric power in this way. There is no prospect whatsoever of the large-scale economic generation of liquid fuels from nuclear, hydroelectric, wind, geothermal, or solar power sources in the near future. Thus the discussion of these technologies is largely irrelevant to the immediate strategic problem we face. In the long run, however, when combined with the switch to alcohol fuels, they can play a key role in...

Free Energy or Helmholtz Potential

Where F ( U -TS) is called the 'Free energy', a term first introduced by Helmholtz. For this reason, F is also sometimes called the Helmholtz potential. (3.7.3) simply states that at constant temperature, the decrease of free energy gives the maximum external work obtainable from a reversible system. In the general case, For such a system, therefore, the free energy available for doing external work has its minimum value. This value is 0 at equilibrium.

Solar Energy References

Solar Energy Fundamentals in Building Design. McGraw-Hill, New York. Baum, V.A. , 1960. Technical characteristics of solar stills of the greenhouse type (in Russian). In Thermal Power Engineering, Utilization of Solar Energy, vol. 2. Academy of Science, USSR Moscow, pp. 122-132. Baum, V.A., Bairamov, R., 1966. Prospects of solar stills in Turkmenia. Solar Energy 10 (1), 38-40. Delyannis, A., 1968. The Patmos solar distillation plant. Solar Energy 11, 113-115. Delyannis, E., 2003. Historic background of desalination and renewable energies. Solar Energy 75 (5), 357-366. Jordan, R.C., Ibele, W.E., 1956. Mechanical energy from solar energy. In Proceedings of the World Symposium on Applied Solar Energy, pp. 81-101. Loef, G.O.G., 1954. Demineralization of saline water with solar energy. OSW Report No. 4, PB 161379, 80pp. Merriam, M.F., 1980. Characteristics and uses of wind machines. In Dicknson, W.C., Cheremisinoff, P.N. (Eds.) Solar Energy Technology Handbook, Part A,...

Thermal Analysis Of Solar Power Plants

Net Analysis Solar Power Plant

Thermal solar power plants are similar to the conventional ones with the exception that a field of concentrating solar collectors replaces the conventional steam boiler. In hybrid plants, a conventional boiler is also present, operating on conventional fuel, usually natural gas, whenever there is a need. Therefore, the thermal analysis of solar power plants is similar to that of any other plant and the same thermodynamic relations are applied. The analysis is greatly facilitated by drafting the cycle on a T-s diagram. In these cases, the inefficiencies of pump and steam turbine should be considered. In this section, the equations of the basic Rankine power cycle are given and two of the more practical cycles, the reheat and the regenerative Rankine cycles, are analyzed through two examples. To solve the problems of these cycles, steam tables are required. Alternatively, the curve fits shown in Appendix 5 can be used. The problems that follow were solved by using steam tables.

Schrodinger entropy and free energy

In his book Schrodinger (1948, p. 71) famously described the process by which an organism survives as continually drawing negative entropy from the environment. In fact on thermodynamical considerations this is not strictly true, as pointed out by Franz Simon soon after the book was first published. In the 1948 edition of his book Schrodinger added a note to this effect, admitting that it might be better to consider organisms as drawing on free energy rather than negative entropy. These niceties of thermodynamic theory are not crucial for the concerns of this book. However, what Schrodinger was describing in thermodynamic terms is an important concept in ecology namely that to survive all organisms must acquire energy from their environment and in so doing produce waste products which they release back into their surroundings. Indeed this is so fundamental that it could be considered the basic concept of ecology. Schrodinger, entropy, and free energy 19 To a (very) naive physicist,...

Stirling Solar Power Generators

Stirling Plant Engine

In addition to SEGS, ISCCS, PV, and updraft tower methods for collecting solar energy, Stirling solar dish systems are also used (Figure 1.38). These units focus the Sun's energy onto H2 in sealed Stirling engines. As the H2 is heated to 732 C (1,350 F), it expands and drives the pistons of the engine. Stirling engines are used on submarines because they are quiet (no combustion takes place). In solar applications, their main advantage is their high efficiency (30 ), which is nearly double that of the best PV collectors. These closed systems do not need to be refilled, only their mirrors need washing every couple of weeks. The operation can be fully automated including start-up in the morning, shutdown in the evening, tracking the Sun, and remote monitoring over the Internet. The displacer piston on the cooling end on the left controls the direction in which the pistons move. It determines if most of the gas is in the piston on the right or left. In phase 4 of the cycle, the displacer...

Solar Power Paris Expositions

Solar Thermal Turbine Diagram

As was seen in Chapter 1, Section 1.5, solar thermal power systems were among the very first applications of solar energy. During the 18th century, solar furnaces capable of melting iron, copper, and other metals were constructed of polished iron, glass lenses, and mirrors. The furnaces were in use throughout Europe and the Middle East. The most notable examples are the solar furnace built by the well-known French chemist Lavoisier in 1774, various concentrators built by the French naturalist Bouffon (1747-1748), and a steam-powered printing press exhibited at the Paris Exposition by Mouchot in 1872. This last application utilized a concentrating collector to supply steam to a heat engine. As was discussed Chapter 9, the direct conversion of solar to electrical energy can be done with photovoltaics, which are solid-state devices. Electricity can also be produced with geothermal energy and wind power. However, with concentrating solar power systems, there are no complicated silicon...

A Brief HiStory Of Solar Energy

John Ericsson Solar

Solar energy is the oldest energy source ever used. The sun was adored by many ancient civilizations as a powerful god. The first known practical application was in drying for preserving food (Kalogirou, 2004). Amazingly, the very first applications of solar energy refer to the use of concentrating collectors, which are, by their nature (accurate shape construction) and the requirement to follow the sun, more difficult to apply. During the 18th century, solar furnaces capable of melting iron, copper, and other metals were being constructed of polished iron, glass lenses, and mirrors. The furnaces were in use throughout Europe and the Middle East. One of the first large-scale applications was the solar furnace built by the well-known French chemist Lavoisier, who, around 1774, constructed powerful lenses to concentrate solar radiation (see Figure 1.4). This attained the remarkable temperature of 1750 C. The furnace used a 1.32 m lens plus a secondary 0.2 m lens to obtain such...

Queries On Solar Power Generated Stirling Engine

I'm confused In Chapter 6, you said that the best photovoltaic panels deliver 20 W m2 on average, in a place with British sunniness. Presumably in the desert the same panels would deliver 40 W m2. So how come the concentrating solar power stations deliver only 15-20 W m2 Surely concentrating power should be even better than plain flat panels Good question. The short answer is no. Concentrating solar power does not achieve a better power per unit land area than flat panels. The concentrating contraption has to track the sun, otherwise the sunlight won't be focused right once you start packing land with sun-tracking contraptions, you have to leave gaps between them lots of sunlight falls through the gaps and is lost. The reason that people nevertheless make concentrating solar power systems is that, today, flat photovoltaic panels are very expensive, and concentrating systems are cheaper. The concentrating people's goal is not to make systems with big power per unit land area. Land area...

Ann applications in solar energy Systems

Artificial neural networks have been used by the author in the field of solar energy, for modeling the heat-up response of a solar steam generating plant (Kalogirou et al., 1998), the estimation of a parabolic trough collector intercept factor (Kalogirou et al., 1996), the estimation of a parabolic trough collector local concentration ratio (Kalogirou, 1996a), the design of a solar steam generation system (Kalogirou, 1996b), the performance prediction of a thermosiphon solar water heater (Kalogirou et al., 1999a), modeling solar domestic water heating systems (Kalogirou et al., 1999b), the long-term performance prediction of forced circulation solar domestic water heating systems (Kalogirou, 2000), and the thermosiphon solar domestic water heating system's long-term performance prediction (Kalogirou and Panteliou, 2000). A review of these models, together with other applications in the field of renewable energy, is given in an article by Kalogirou (2001). In most of those models, the...

Operating and New Solar Power Plants

The first concentrating trough-type solar power plant in the United States was built in 1988. It is the 1 mW Saguaro plant located north of Tucson, Arizona, and was built for Arizona Public Service (APS). It covers 1 km2 and has parabolic trough-shaped mirrors. Today, the largest solar power plant in the United States is the 22-year-old thermal plant in California's Mojave Desert, which has a combined total capacity of 354 mW. At Kramer Junction, California, nine solar power plants, each 30 mW or larger, have been in operation for two decades. The yearly insolation in the area is 2,940 kWh m2. Plant efficiencies range from 10 to 17 , and their capital costs range from 2,500 to 3,500 per kWp.* The cost of generated electricity from these plants drops as their size increases, and ranges from 10 to 17 kWh. A number of new solar power plants are under construction. In 2007, First Solar signed a contract to produce 685 mW of solar collectors over 5 years for 1.28 billion, or at a unit cost...

Types Of Renewable Fuels Solar Energy

This is the energy radiated to the earth from the sun. Solar thermal devices use direct heat from the sun, concentrating it in some manner to produce heat at useful temperatures. The amount of energy that reaches the earth and can be tapped for our use depends very much on time and geography. What that means is that there'll be more solar energy during the day than during the night, and also that the tropics such as Africa

Solar energy in building design

All buildings benefit from unplanned gains of solar energy through windows and, to a lesser extent, through the warming of walls and roofs. This is called 'passive solar gain' for a typical house in the UK it will contribute about 15 of the annual space heating requirements. With 'passive solar design' this can relatively easily and inexpensively be increased to around 30 while increasing the overall degree of comfort and amenity. The main features of such design are to place, so far as is possible, the principal living rooms with their large windows on the south side of the house in the Northern hemisphere, with the cooler areas such as corridors, stairs, cupboards and garages with the minimum of window area arranged to provide a States could be generated from the solar energy falling on PV cells over an area of 400 km square or on CSP installations covering a somewhat smaller area. However, at the present time for large-scale electricity provision, neither is competitive in cost...

Direct Use of Solar Energy

All direct uses of solar energy for electricity generation suffer from the dilute nature of the solar source. The average flux of solar energy at the surface of the Earth is about 200 W m2. Thus, it requires about 5 km2 to collect 1 GW of incident solar energy. The area required for electricity generation depends on the efficiency of conversion from solar energy to electricity. One potential source of electricity is biomass, used as a fuel in a steam turbine plant. The main source of biomass now used in electricity generation is wastes, including wastes from the forest product industry. However, the amounts of such wastes are limited. A major increase in biomass use for electricity generation would require dedicated biomass plantations and adequate supplies of water and fertilizer. As estimated by David Hall and colleagues, the practical maximum yields of biomass in temperate climates corresponds to an annual average efficiency of about 1 for conversion from solar energy to chemical...

Solar panels and inverters

For grid-connected applications, more cells are necessary. Typical units are designed to provide up to 200 W. The individual cells are normally mounted behind a glass protective barrier similar to a vehicle windscreen. The whole assembly is then encapsulated to protect it from the weather and framed with aluminium extrusions. Such assemblies are called solar panels. A solar panel provides a stable direct current output. If this is to form a part of a grid-connected solar power system, perhaps on the roof of a household, it must be converted to AC at the grid voltage. This is carried out by an inverter. A typical household system will require a 2 kW inverter.

Solar Energy Utilization in Israel

There is no single legislation concerning solar energy utilization in Israel. The above-mentioned Article 9 of the Law for Planning and Building (1970) 4 is probably the most important solar legislation, and has been the government's predominant contribution to Israel's success in the solar area. The law requires the builder (not the homeowner ), since 1980, to install a solar water heating system in every new building. Other laws and regulations describe in detail the size of the installation required for the various types of buildings, set minimum standards for the quality of the solar equipment and installation, and provide the regulations for retrofit installation of solar water heaters in existing multi-apartment buildings. Based on government data 5 an average single-family domestic solar water heater saves 1250 kWh electric power per year the total contribution to the country is about 1.6 billion kWh per year, 21 of the electricity for the domestic sector or 5.2 of the national...

Economic Limitations of Solar Energy

Today, the major problem facing solar energy - especially for the production of electricity - is its cost, which is still high when compared not only to fossil fuels but also to renewables such as wind or hydropower. Despite the free and inexhaustible solar power source, the up-front cost for the equipment to collect and store solar energy is high. Likewise, due to the diffuse nature of sunshine, the collecting area necessary to produce large amounts of solar energy is by necessity large. The absence of sunlight during night-time and reduced insolation in cloudy conditions also necessitates back-up generators or expensive and limited-energy storage batteries. With continued research and technological improvements however, solar energy will in the long run certainly become an important part of our energy-mix.

Solar Power

Olar power has been the Next Big Thing for as long as most people have been alive. Way back in the 1970s, the idea of using clean, abundant, free sunlight to break the grip of Big Oil first led homeowners to bolt solar panels onto their roofs and wait gleefully for their meters to start running backward, and they've been at it ever since. Unfortunately, almost without exception, those early solar arrays ended up serving only the social consciences of their owners. Sunshine may have been free, but solar power was anything but. Until very recently, solar panels were so inefficient that they cost more than they saved, which is why, despite all that free sunlight, they currently adorn only a relative handful of U.S. homes. But during solar's long gestation period, researchers were making steady progress. Each year, the ability to turn sunlight into energy improved. And now, at last, solar is ready for prime time. How ready Well, with a little help from improved energy storage technology,...

Solar Energy

Our planet receives as much solar energy in 30-40 minutes as humankind uses in a year. Solar energy is the most abundant energy source on the planet. It is already being used as the energy source of space vehicles and space stations. (The energy source on the International Space Station is an acre-size solar collector receiving an insolation of 1.37 kW m2.) The capacity of a collector is expressed in terms of its peak power production (wp).* Small solar power plants can be built on the outskirts of towns, while large ones can be built in the less inhabited high-insolation areas of the planet. Solar panels can be mounted above the ground so that grass and flowers can continue to flourish between and below the rows of panels. Care should be taken that sufficient amounts of rainwater can drop through and between adjoining panels so that vegetation can survive. The first costs of solar power plants are similar to those of carbon capturing advanced fossil or nuclear power plants (Table...

Solar Energy Storage

The availability of solar energy is subject to diurnal-, seasonal-, and weather-related variations. Therefore, if solar energy is to meet continuous energy demands, it must be stored. On small installations, such storage can be provided by high-density batteries. (NGK Insulators Ltd. of Japan, for example, manufactures sodium-sulfur batteries that can store 7 mWh.) On midsized installations, pumped hydrostorage can be considered. For larger installations, the compressing of air into underground caverns has been suggested. This method is inefficient, and to my knowledge only two compressed air energy storage systems are in operation (neither serving the storage of solar energy). In even larger installations, one solution is the storage of heat in high-temperature (400 C or higher) oil or in molten salt. Hot oil storage is more common, but in other cases such as the 64 mW solar power plant called Solar One, in Boulder City, Nevada, excess solar energy is planned to be stored in molten...

The New Solar Power

Solar power has advanced significantly since the days of inefficient photovoltaics. In California, solar power is being built into roof tiles, and talk is that nanotechnology will make any surface on which the sun shines a source of power windows, for example. Experiments have been undertaken with a new form of solar energy Concentrating Solar Power (CSP). In our lifetimes, as homes feed power into the electrical grid, electric meters will run backward, feeding power into the electrical grid from individual homes and businesses, using carbon-based fuels only as backup. A 380-foot concrete tower surrounded by 600 huge mirrors near Seville, Spain, is part of a new CSP plant that produces solar power that is commercially viable on a large scale. In this case, the power station, constructed by Abengoa S.A., can supply about 6,000 homes. Spain and other European countries are subsidizing CSP and other solar technologies to move away from fossil fuels. According to the consulting firm...

Solar Power Tower

Solar Elec Power Tower

Figure 4-8 is a sketch of a solar power tower with a heliostat field. The heliostat field is a field of large, Sun-tracking mirrors called heliostats arranged in rings around a central receiver tower. The heliostats concentrate sunlight on a receiver at the top of the tower. The solar energy heats a fluid inside the receiver. Figure 4-8. Solar Power Tower Incident Sunlight Figure 4-8. Solar Power Tower Incident Sunlight The first solar power plant based on the solar power tower concept was built in the Mojave Desert near Barstow, California in the 1980's. The solar-thermal power plant at Barstow used 1900 heliostats to reflect sunlight to the receiver at the top of a 300-foot tall tower. The sunlight generates heat to create steam. The steam is used to drive a turbine or it can be stored for later use. The first solar power tower, Solar One, demonstrated the feasibility of collecting solar energy and converting it to electrical energy. Solar One was a 10 megawatt power plant. The heat...

Active Solar Energy

Active Solar Energy

Active solar energy refers to the design and construction of systems that collect and convert solar energy into other forms of energy such as heat and electrical energy. Active solar energy technologies are typically mechanical systems that are used to collect and concentrate solar energy. We will discuss solar heat collectors and a solar power plant as illustrations of active solar energy technology.

Solar Power Towers

Within a few years, another type of solar thermal electric power plant, the solar power tower, will enter the commercial power arena. This plant uses a field of specially designed solar-tracking mirrors called heliostats that concentrate sunlight from many angles simultaneously on a tower-mounted heat receptor. From there the energy goes to power an electric generator or to a coupled solar energy storage tank of molten salt for cloudy day and nighttime operation.

Overtemperature protection

Periods of high insolation and low load result in overheating of the solar energy system. Overheating can cause liquid expansion or excessive pressure, which may burst piping or storage tanks. Additionally, systems that use glycols are more problematic, since glycols break down and become corrosive at temperatures greater than 115 C. Therefore, the system requires protection against this condition. The solar system can be protected from overheating by a number of methods, such as

Passive solar Buildings

Finally, another area of solar energy is related to passive solar buildings. The term passive system is applied to buildings that include, as integral parts of the building, elements that admit, absorb, store, and release solar energy and thus reduce the need for auxiliary energy for comfort heating. These elements have to do with the correct orientation of buildings, the correct sizing of openings, the use of overhangs and other shading devices, and the use of insulation and thermal mass. For many years however, many of these were used based mostly on experience. These are investigated in Chapter 6 of this book.

Solar Space Heating And CooliNG

Active solar space systems use collectors to heat a fluid, storage units to store solar energy until needed, and distribution equipment to provide the solar energy to the heated spaces in a controlled manner. Additionally, a complete system includes pumps or fans for transferring the energy to storage or to the load these require a continuous availability of non-renewable energy, generally in the form of electricity. During daytime, the solar energy system absorbs solar radiation with collectors and conveys it to storage using a suitable fluid. As the building requires heat, this is obtained from storage. Control of the solar energy system is exercised by differential temperature controllers, described in Chapter 5, Section 5.5. In locations where freezing conditions may occur, a low-temperature sensor is installed on the collector to control the solar pump when a preset temperature is reached. This process wastes some stored heat, but it prevents costly damage

Space Heating and Service Hot Water

When solar energy is available and heat is not required in the building, solar energy is added to storage. 2. When solar energy is available and heat is required in the building, solar energy is used to supply the building load demand. 3. When solar energy is not available, heat is required in the building, and the storage unit has stored energy, the stored energy is used to supply the building load demand. 4. When solar energy is not available, heat is required in the building, and the storage unit has been depleted, auxiliary energy is used to supply the building load demand. 5. When the storage unit is fully heated, there are no loads to meet, and the collector is absorbing heat, solar energy is discarded. In addition to the operation modes just outlined, the solar energy system is usually used to provide domestic hot water. These modes are usually controlled by thermostats. So, depending on the load of each service, heating, cooling, or hot water, the thermostat that is not...

Solarmechanical systems

Solar-mechanical systems utilize a solar-powered prime mover to drive a conventional air-conditioning system. This can be done by converting solar energy into electricity by means of photovoltaic devices, then utilizing an electric motor to drive a vapor compressor. The photovoltaic panels, however, have a low field efficiency of about 10-15 , depending on the type of cells used, which results in low overall efficiencies for the system. The solar-powered prime mover can also be a Rankine engine. In a typical system, energy from the collector is stored, then transferred to a heat exchanger, and finally energy is used to drive the heat engine (see Chapter 10). The heat engine drives a vapor compressor, which produces a cooling effect at the evaporator. As shown in Figure 6.18, the efficiency of the solar collector decreases as the operating temperature increases, whereas the efficiency of the heat engine of the system increases as the operating temperature increases. The two...

Intentional Thermal Mass Effects

Thermal Storage Walls

To make the best use of thermal mass, the building should be designed with this objective in mind. Intentional use of the thermal mass can be either passive or active. Passive solar heating is a common application that utilizes the thermal mass of the building to provide warmth when no solar energy is available. Passive cooling applies the same principles to limit the temperature rise during

Solar Cooling With Absorption Refrigeration

Absorption Solar Refrigeration

A schematic diagram of a solar-operated absorption refrigeration system is shown in Figure 6.28. The refrigeration cycle is the same as the ones described in Section 6.4.2. The difference between this system and the traditional fossil fuel-fired units is that the energy supplied to the generator is from the solar collector system shown on the left side of Figure 6.28. Due to the intermittent nature of available solar energy, a hot water storage tank is needed thus the collected energy is first stored in the tank and used as an energy source in the generator to heat the strong solution when needed. The storage tank of the solar heating system is used for this purpose. When the storage tank temperature is low, the auxiliary heater is used to top it off to the required generator temperature. Again, the same auxiliary heater of the space heating system can be used, at a different set temperature. If the storage tank is completely depleted, the storage is bypassed, as in the space heating...

Challenges In Absorption Refrigeration

Centralized Solar Energy Fig

Test and simulation of a solar-powered absorption cooling machine. Sol. Energy 59 (4-6), 155-162. Hsieh, J.S., 1986. Solar Energy Engineering. Prentice-Hall, Englewood Cliffs, NJ. Klein, S.A., et al., 2005. TRNSYS version 16 Program Manual, Solar Energy Laboratory, University of Wisconsin, Madison. Norton, B., 1992. Solar Energy Thermal Technology. Springer-Verlag, London. The principle of operation of collectors and other components of the solar systems outlined in the previous chapters apply as well to industrial process heat applications. These applications, however, have some unique features the main ones are the scale on which they are applied and the integration of the solar energy supply with an auxiliary energy source and the industrial process. Generally, two primary problems need to be considered when designing an industrial process heat application. These concern the type of energy to be employed and the temperature at which the heat is to be...

Classification of Solar Distillation Systems

Wick Distillation

Frick and Sommerfeld (1973), Sodha et al. (1981), and Tiwari (1984) developed a simple multiple-wick-type solar still, in which blackened wet jute cloth forms the liquid surface. Jute cloth pieces of increasing lengths were used, separated by thin black polyethylene sheets resting on foam insulation. Their upper edges were dipped in a saline water tank, where capillary suction provided a thin liquid sheet on the cloth, which was evaporated by solar energy. The results showed a 4 increase in still efficiency above conventional stills.

Lithiumwater absorption systems

How Hot Water Absorption Chiller Works

Haim et al. (1992) performed a simulation and analysis of two open cycle absorption systems. Both systems comprise a closed absorber and evaporator, as in conventional single-stage chillers. The open part of the cycle is the regenerator, used to re-concentrate the absorber solution by means of solar energy. The analysis was performed with a computer code developed for modular simulation of absorption systems under varying cycle configurations (open and closed cycle systems) and with different working fluids. Based on the specified design features, the code calculates the operating parameters in each system. Ghaddar et al. (1997) presented the modeling and simulation of a solar absorption system for Beirut. The results showed that each ton of refrigeration requires a minimum collector area of 23.3 m2 with an optimum water storage capacity ranging from 1000-1500 L for the system to operate solely on solar energy for about 7 h d. The monthly solar fraction of total energy use in cooling...

Direct Circulation Systems

Direct Circulation System

A schematic diagram of a direct circulation system is shown in Figure 5.9. In this system, a pump is used to circulate potable water from storage to the collectors when there is enough available solar energy to increase its temperature and then return the heated water to the storage tank until it is needed. Because a pump is used to circulate the water, the collectors can be mounted either above or below the storage tank. Direct circulation systems often use a single storage tank equipped with an auxiliary water heater, but two-tank storage systems can also be used. An important feature of this configuration is the spring-loaded

Desalination Processes

Fossil fuel source, nuclear energy, or a non-conventional solar energy source or geothermal energy. In the membrane processes, electricity is used for either driving high-pressure pumps or ionization of salts contained in the seawater. Solar energy can be used for seawater desalination by producing either the thermal energy required to drive the phase change processes or the electricity required to drive the membrane processes. Solar desalination systems are thus classified into two categories direct and indirect collection systems. As their name implies, direct collection systems use solar energy to produce distillate directly in the solar collector, whereas in indirect collection systems, two subsystems are employed (one for solar energy collection and one for desalination). Conventional desalination systems are similar to solar energy systems, since the same type of equipment is applied. The prime difference is that, in the former, either a conventional boiler is used to provide...

Suntracking Concentrating Collectors

Sun Collector Convection

The working fluid can achieve higher temperatures in a concentrator system than a flat-plate system of the same solar energy-collecting surface. This means that a higher thermodynamic efficiency can be achieved. 5. Owing to the relatively small area of receiver per unit of collected solar energy, selective surface treatment and vacuum insulation to reduce heat losses and improve the collector efficiency are economically viable. In concentrating collectors solar energy is optically concentrated before being transferred into heat. Concentration can be obtained by reflection or refraction of solar radiation by the use of mirrors or lenses. The reflected or refracted

Horizontal ns axis with ew tracking

Day Energy Curve

The basic geometry of this configuration is shown in Figure 2.10d. The greatest advantage of this arrangement is that very small shadowing effects are encountered when more than one collector is used. These are present only at the first and last hours of the day. In this case the curve of the solar energy collected during the day is closer to a cosine curve function (see Figure 2.16).

Solar sorption cooling

Adsorption cooling is the other group of sorption air conditioners that utilizes an agent (the adsorbent) to adsorb the moisture from the air (or dry any other gas or liquid), then uses the evaporative cooling effect to produce cooling. Solar energy can be used to regenerate the drying agent. Solid adsorbents include silica gels, zeolites, synthetic zeolites, activated alumina, carbons, and synthetic polymers (ASHRAE, 2005). Liquid adsorbents can be triethylene glycol solutions of lithium chloride and lithium bromide solutions.

Optimum Collector Temperature

Iso 9806 Report

Bejan, A., Kearney, D.W., Kreith, F., 1981. Second law analysis and synthesis of solar collector systems. J. Solar Energy Engin. 103, 23-28. Brandemuehl, M.J., Beckman, W.A., 1980. Transmission of diffuse radiation through CPC and flat-plate collector glazings. Solar Energy 24 (5), 511-513. Feuermann, D., Gordon, J.M., 1991. Analysis of a two-stage linear Fresnel reflector solar concentrator. ASME J. Solar Energy Engin. 113, 272-279. Francia, G., 1968. Pilot plants of solar steam generation systems. Solar Energy 12, 51-64. Garg, H.P., Hrishikesan, D.S., 1998. Enhancement of solar energy on flat-plate collector by plane booster mirrors. Solar Energy 40 (4), 295-307. Geyer, M., Lupfert, E., Osuna, R., Esteban, A., Schiel, W., Schweitzer, A., Zarza, E., Nava, P., Langenkamp, J., Mandelberg, E., 2002. Eurotrough-parabolic trough collector developed for cost efficient solar power generation. In Proceedings of 11th Solar PACES International Symposium on Concentrated Solar Power and Chemical...

Parabola construction

Eurotrough Drive System

To achieve cost-effectiveness in mass production, the collector structure must feature not only a high stiffness-to-weight ratio, to keep the material content to a minimum, but also be amenable to low-labor manufacturing processes. A number of structural concepts have been proposed, such as steel framework structures with central torque tubes or double V trusses and fiberglass (Kalogirou et al., 1994b). A recent development in this type of collectors is the design and manufacture of the EuroTrough, a new parabolic trough collector, in which an advanced lightweight structure is used to achieve cost-efficient solar power generation (Lupfert et al., 2000 Geyer et al., 2002). Based on environmental test data to date, mirrored glass appears to be the preferred mirror material, although self-adhesive reflective materials with lifetimes of 5-7 years exist in the market. A parabolic dish reflector (PDR), shown schematically in Figure 3.20a, is a point-focus collector that tracks the sun in...

Thermal Analysis Of Flatplate Collectors

Tilted Flat Plate Collector

The prediction of collector performance requires information on the solar energy absorbed by the collector absorber plate. The solar energy incident on a tilted surface can be found by the methods presented in Chapter 2. As can be seen from Chapter 2, the incident radiation has three special components beam, diffuse, and ground-reflected radiation. This calculation depends on the radiation model employed. Using the isotropic model on an hourly basis, Eq. (2.97) can be modified to give the absorbed radiation, S, by multiplying each term with the appropriate transmittance-absorptance product as follows plate is assumed to be diffuse, so the fraction (1 - a)T that strikes the glass cover is diffuse radiation and (1 - a)TpD is reflected back to the absorber plate. The multiple reflection of diffuse radiation continues so that the fraction of the incident solar energy ultimately absorbed is

The Multi Stage Flash MSF Process

Multi Stage Flash Process

MSF is the most widely used desalination process in terms of capacity. This is due to the simplicity of the process, performance characteristics, and scale control (Kalogirou, 1997b). A disadvantage of MSF is that precise pressure levels are required in the different stages therefore, some transient time is required to establish the normal running operation of the plant. This feature makes the MSF relatively unsuitable for solar energy applications unless a storage tank is used for thermal buffering. Another type of MEB evaporator is the multiple effect stack (MES). This is the most appropriate type for solar energy applications. It has a number of advantages, the most important of which is its stable operation between virtually 0 and 100 output, even when sudden changes are made, and its ability to follow a varying steam supply without upset. In Figure 8.8, a four-effect MES evaporator is shown. Seawater is sprayed into the top of the evaporator and descends as The...

Solar industrial Air and Water Systems

Auxiliary Solar Heating Sytems

A solar energy system may deliver energy to the load either in series or parallel with the auxiliary heater. In a series arrangement, shown in Figure 7.2, energy is used to pre-heat the load heat transfer fluid, which may be heated more, if necessary, by the auxiliary heater, to reach the required temperature. If the temperature of the fluid in the storage tank is higher than that required by the load, a three-way valve, also called a tempering valve, is used to mix it with cooler make-up or One of the most important design characteristics to consider when designing a solar industrial process heat system is the time matching of the solar energy source to the load. As was seen in the previous chapter, heating and cooling loads vary from day to day. In industrial process heat systems, however, the loads are pretty much constant and small variations are due to the seasonal variation of the make-up water temperature.

Solarrelated air conditioning

Desiccant Wheel

Some components of systems installed for the purpose of heating a building can also be used to cool it but without the direct use of solar energy. Examples of these systems can be heat pumps, rock bed regenerators, and alternative cooling technologies or passive systems. Heat pumps were examined in Section 6.3.5. The other two methods are briefly introduced here. Rock bed regenerator. Rock bed (or pebble bed) storage units of solar air heating systems can be night-cooled during summer to store cold for use the following day. This can be accomplished during the night when the temperatures and humidities are low by passing outside air through an optional evaporative cooler, through the pebble bed, and to the exhaust. During the day, the building can be cooled by passing room air through the pebble bed. A number of applications using pebble beds for solar energy storage are given by Hastings (1999). For such systems, airflow rates should be kept to a minimum so as to minimize fan power...

Collector test results and preliminary collector selection

Collector testing is required to evaluate the performance of solar collectors and compare different collectors to select the most appropriate one for a specific application. As can be seen from Sections 4.1-4.5, the tests show how a collector absorbs solar energy and how it loses heat. They also show the effects of angle of incidence of solar radiation and the significant heat capacity effects, which are determined from the collector time constant.

Storage capacity correction

It can be proven that the annual performance of liquid-based solar energy systems is insensitive to the storage capacity, as long as this is more than 50 L of water per square meter of collector area. For the f-chart of Figure 11.2, a standard storage capacity 75 L of stored water per square meter of collector area was considered. Other storage capacities can be used by modifying the factor X by a storage size correction factor Xc X, given by (Beckman et al., 1977)

Direct Collection Systems

Double Slope Solar Still

Figure 8.1 shows the various components of energy balance and thermal energy loss in a conventional double-slope symmetrical solar distillation unit (also known as a roof-type or greenhouse-type solar still). The still consists of an airtight basin, usually constructed out of concrete, galvanized iron sheet (GI), or fiber-reinforced plastic (FRP), with a top cover of transparent material such as glass or plastic. The inner surface of the base, known as the basin liner, is blackened to efficiently absorb the solar radiation incident on it. There is also a provision to collect distillate output at the lower ends of the top cover. The brackish or saline water is fed inside the basin for purification using solar energy. The stills require frequent flushing, which is usually done during the night. Flushing is performed to prevent salt precipitation. Design problems encountered with solar stills are brine depth, vapor tightness of the enclosure, distillate leakage, methods of thermal...

Backpropagation architecture

The third category is the feed-forward network with multiple hidden slabs. These network architectures are very powerful in detecting different features of the input vectors when different activation functions are given to the hidden slabs. This architecture has been used in a number of engineering problems for modeling and prediction with very good results (see the later section, ANN Applications in Solar Energy Systems). This is a feed-forward architecture with three hidden slabs, as shown in Figure 11.19. The information processing at each node is performed by combining all input numerical information from upstream nodes in a weighted average of the form

Collector flow rate correction

And relief of pressure through the relief valve. Although the product of the mass flow rate and the specific heat of the fluid flowing through the collector strongly affects the performance of the solar energy system, the value used is seldom lower than the value used for the f-chart development. Additionally, since an increase in the collector flow rate beyond the nominal value has a small effect on the system performance, Figure 11.2 is applicable for all practical collector flow rates.

Location of Auxiliary Heater

One important consideration concerning the storage tank is the decision as to the best location for the auxiliary heater. This is especially important for solar space-heating systems because larger amounts of auxiliary energy are usually required and storage tank sizes are large. For maximum utilization of the energy supplied by an auxiliary source, the location of this energy input should be at the load, not at the storage tank. The supply of auxiliary energy at the storage tank will undoubtedly increase the temperature of fluid entering the collector, resulting in lower collector efficiency. When a water-based solar energy system is used in conjunction with a warm-air space heating system, the most economical means of auxiliary energy supply is by the use of a fossil fuel-fired boiler. In case of bad weather, the boiler can take over the entire heating load. When a water-based solar energy system is used in conjunction with a water space heating system or to supply the heated water...

Passive Space Heating Design

Passive solar heating systems require little, if any, non-renewable energy to function. Every building is passive in the sense that the sun tends to warm it by day and it loses heat at night. Passive systems incorporate solar energy collection, storage, and distribution into the architectural design of the building and make minimal or no use of mechanical equipment, such as fans, to deliver the collected energy. Passive solar heating, cooling, and lighting design must consider the building envelope and its orientation, the thermal storage mass, window configuration and design, the use of sun spaces, and natural ventilation. As part of the design process, a preliminary analysis must be undertaken to investigate the possibilities for saving energy through solar energy and the selection of the appropriate passive technique. The first step to consider for each case investigated should include an analysis of the climatic data of the site and definition of the comfort requirements of the...

Differential temperature controller

Williams Pump Controller

One of the most important components of an active solar energy system is the temperature controller because a faulty control is usually the cause of poor system performance. In general, control systems should be as simple as possible and should use reliable controllers, which are available nowadays. One of the critical parameters that need to be decided by the designer of the solar system is where to locate the collector, storage, over-temperature, and freezing-temperature sensors. The use of reliable, good-quality devices is required for many years of trouble-free operation. As was seen in the previous sections of this chapter, the control system should be capable of handling all possible system operating modes, including heat collection, heat rejection, power failure, freeze protection, and auxiliary heating. The basis of solar energy system control is the differential temperature controller (DTC). This is simply a fixed temperature difference (AT) thermostat with hysteresis. The...

Renewable Energy Technologies

Another factor of considerable importance in many countries is the ability of renewable energy technologies to generate jobs. The penetration of a new technology leads to the development of new production activities, contributing to the production, market distribution, and operation of the pertinent equipment. Specifically for the case of solar energy collectors, job creation is mainly related to the construction and installation of the collectors. The latter is a decentralized process, since it requires the installation of equipment in every building or for every individual consumer. In this book, emphasis is given to solar thermal systems. Solar thermal systems are non-polluting and offer significant protection of the environment. The reduction of greenhouse gas pollution is the main advantage of utilizing solar energy. Therefore, solar thermal systems should be employed whenever possible to achieve a sustainable future. Solar systems, including solar thermal and photovoltaics,...

Energy Demand And Renewable Energy

Many alternative energy sources can be used instead of fossil fuels. The decision as to what type of energy source should be utilized in each case must be made on the basis of economic, environmental, and safety considerations. Because of the desirable environmental and safety aspects it is widely believed that solar energy should be utilized instead of other alternative energy forms because it can be provided sustainably without harming the environment. Many scenarios describe how renewable energy will develop in coming years. In a renewable energy-intensive scenario, global consumption of renewable resources reaches a level equivalent to 318 EJ (exa, E 1018) per annum (a) of fossil fuels by 2050 a rate comparable to the 1985 total world energy consumption, which was equal to 323 EJ. Although this figure seems to be very large, it is less than 0.01 of the 3.8 million EJ of solar energy reaching the earth's surface each year. The total electric energy produced from intermittent...

Load Heat Exchanger Size Correction

Heat Exchanger Correction Factor

The size of the load heat exchanger strongly affects the performance of the solar energy system. This is because the rate of heat transfer across the load heat exchanger directly influences the temperature of the storage tank, which consequently affects the collector inlet temperature. As the heat exchanger used to heat the building air is reduced in size, the storage tank temperature must increase to supply the same amount of heat energy, resulting in higher collector inlet temperatures and therefore reduced collector performance. To account for the load heat exchanger size, a new dimensionless parameter is specified, Z, given by (Beckman et al., 1977) From Eq. (11.12), the annual fraction of load covered by the solar energy system is Klein et al. (1977) developed for air-based systems a design procedure similar to that for liquid-based systems. The f-chart for air-based systems is developed for the standard solar air-based solar energy system, shown in Figure 11.5. This is the same...

Pipes Supports and Insulation

The material of a solar energy system piping may be copper, galvanized steel, stainless steel, or plastic. All pipes are suitable for normal solar system operation except plastic piping, which is used only for low temperature systems, such as swimming pool heating. Another problem related to plastic piping is

Reforming of Fuels

Solar energy is essentially unlimited and its utilization does not create ecological problems. However, solar radiation reaching the earth is intermittent and not distributed evenly. There is thus a need to collect and store solar energy and transport it from the sunny uninhabited regions, such as deserts, to industrialized populated regions, where great quantities of energy are needed. An effective way to achieve this process is by the thermochemical conversion of solar energy into chemical fuels. This method provides a thermochemically efficient path for storage and transportation. For this purpose, high-concentration-ratio collectors, similar to the ones used for power generation (see Chapter 10), are required. By concentrating solar radiation in receivers and reactors, one can supply energy to high-temperature processes to drive endothermic reactions. In the future, it is anticipated that most of the hydrogen required to power fuel cells could be generated from renewable sources,...

Valves

Special attention must be paid to the proper selection and location of valves in solar energy systems. Careful selection and installation of a sufficient number of Pressure-reducing valves. Pressure-reducing valves are used to reduce the pressure of make-up city water to protect the system from overpressure. These valves should be installed together with a check valve to avoid feeding the city circuit with water from the solar energy system.

Distributed type

Distributed, natural circulation, solar energy dryers are also called indirect passive dryers. A typical distributed natural circulation solar energy dryer comprises an air heating solar energy collector, appropriate insulated ducting, a drying chamber, and a chimney, as shown in Figure 7.14. In this design, the crop is located on trays or shelves inside an opaque drying chamber, which does not allow the solar radiation to reach the product directly. Air, which is heated during its passage through an air solar collector, is ducted to the drying chamber to dry the product. Because the crops do not receive direct sunshine, caramelization (formation of sugar crystals on the crop surface) and localized heat damage do not occur. Therefore, indirect dryers are usually used for some perishables and fruits, for which the vitamin content of the dried product is reduced by the direct exposure to sunlight. The color retention in some highly pigmented commodities is also very adversely affected...

Solar Drying

Another application of solar energy is solar drying. Solar dryers have been used primarily by the agricultural industry. The objective in drying an agricultural product is to reduce its moisture contents to a level that prevents deterioration within a period of time regarded as the safe storage period. Drying is a dual process of heat transfer to the product from a heating source and mass transfer of moisture from the interior of the product to its surface and from the surface to the surrounding air. For many centuries farmers were using open-sun drying. Recently however, solar dryers have been used which are more effective and efficient. In solar drying, solar energy is used as either the sole heating source or a supplemental source, and the air flow can be generated by either forced or natural convection. The heating procedure could involve the passage of the preheated air through the product or by directly exposing the product to solar radiation, or a combination of both. The major...

Solar Cooling

The role of designers and architects is very important, especially with respect to solar energy control, the utilization of thermal mass, and the natural ventilation of buildings, as was seen in Section 6.2.6. In effective solar energy control, summer heat gains must be reduced, while winter solar heat gains must be maximized. This can be achieved by proper orientation and shape of the building, the use of shading devices, and the selection of proper construction materials. Thermal mass, especially in hot climates with diurnal variation of ambient temperatures exceeding 10 C, can be used to reduce the instantaneous high cooling loads, reduce energy consumption, and attenuate indoor temperature swings. Correct ventilation can enhance the roles of both solar energy control and thermal mass. In intermediate seasons in hot, dry climates, processes such as evaporative cooling can offer energy conservation opportunities. However, in summertime, due to the high temperatures, low-energy...

Greenhouses

Another application intended for the agricultural industry is the greenhouse. The basic function of a greenhouse is to provide environmental conditions that accelerate the process of photosynthesis. Photosynthesis is the driving force for plant growth, in which CO2 is transformed into H2O, using solar energy, to carbohydrates and oxygen. Photosynthesis is highly sensitive to environmental factors.

Wind Energy

Wind is generated by atmospheric pressure differences, driven by solar power. Of the total of 175,000 TW of solar power reaching the earth, about 1200 TW (0.7 ) are used to drive the atmospheric pressure system. This power generates a kinetic energy reservoir of 750 EJ with a turnover time of 7.4 days (Soerensen, 1979). This conversion process takes place mainly in the upper layers of the atmosphere, at around 12 km height (where the jet streams occur). If it is assumed that about 4.6 of the kinetic power is available in the lowest strata of the atmosphere, the world wind potential is on the order of 55 TW. Therefore it can be concluded that, purely on a theoretical basis and disregarding the mismatch between supply and demand, the wind could supply an amount of electrical energy equal to the present world electricity demand.

Hydrogen

Hydrogen is an energy carrier and not a fuel, as is usually wrongly asserted. Hydrogen produced electrolytically from wind or direct solar power sources and used in fuel cell vehicles can provide zero-emission transportation. As for any fuel, appropriate safety procedures must be followed. Although the hazards of hydrogen are different from those of the various hydrocarbon fuels now in use, they are no greater.

Semiconductors

Cadmium Telluride Band Diagram

A photovoltaic PV generator is mainly an assembly of solar cells, connections, protective parts, and supports. As was seen already, solar cells are made of semiconductor materials, usually silicon, and are specially treated to form an electric field with positive on one side (backside) and negative on the other side, facing the sun. When solar energy (photons) hits the solar cell, electrons are knocked loose from the atoms in the semiconductor material, creating electron-hole pairs. If electrical conductors are attached to the positive and negative sides, forming an electrical circuit, the electrons are captured in the form of electric current, called photocurrent, Iph. As can be understood from this description, during darkness the solar cell is not active and works as a diode, i.e., a p-n junction that does not produce any current or voltage. If, however, it is connected to an external, large voltage supply, it generates a current, called the diode or dark current, ID. A solar cell...

Solar Ponds

Solar Ponds Temperature Gradient

Salt gradient lakes, which exhibit an increase in temperature with depth, occur naturally. A salt gradient solar pond is a body of saline water in which the salt concentration increases with depth, from a very low value at the surface to near saturation at the depth of usually 1-2 m (Tabor, 1981). The density gradient inhibits free convection, and the result is that solar radiation is trapped in the lower region. Solar ponds are wide-surfaced collectors in which the basic concept is to heat a large pond or lake of water in such a way as to suppress the heat losses that would occur if less dense heated water is allowed to rise to the surface of the pond and lose energy to the environment by convection and radiation (Sencan et al., 2007). As shown in Figure 10.12, this objective can be accomplished if a stagnant, highly transparent insulating zone is created in the upper part of the pond to contain the hot fluid in the lower part of the pond. In a non-conventional solar pond, part of...

Materials Processing

Solar energy material processing involves affecting the chemical conversion of materials by their direct exposure to concentrated solar energy. For this purpose, we use solar furnaces made of high-concentration, hence, high-temperature, collectors of the parabolic dish or heliostat type. Solar energy can also assist in the processing of energy-intensive, high-temperature materials, as in

Water Systems

Solar Space Heating Systems Diagram

If the climate is characterized by frequent sub-freezing temperatures, positive freeze protection with the use of an antifreeze solution in a closed collector loop is necessary. A detailed schematic of such a liquid-based system is shown in Figure 6.14. A collector heat exchanger is used between the collector and the storage tank, which allows the use of antifreeze solutions to the collector circuit. The most usual solution is water plus glycol. Relief valves are also required to dump excess energy if over-temperature conditions exists. To top off' the energy available from the solar energy system, auxiliary energy is required. It should be noted that the connections to the storage tank should be done in such a way as to enhance stratification, i.e., cold streams to be connected at the bottom and hot streams at the top. In this way, cooler water or fluid is supplied to the collectors to maintain the best possible efficiency. In this type of system, the auxiliary energy is never used...

Heat pump Systems

Heat Pump Install Parallel

Active solar energy systems can also be combined with heat pumps for domestic water heating or space heating. In residential heating, the solar energy system can be used in parallel with a heat pump, which supplies auxiliary energy when the sun is not available. Additionally, for domestic water systems requiring high water temperatures, a heat pump can be placed in series with the solar storage tank. A heat pump is a device that pumps heat from a low-temperature source to a higher-temperature sink. Heat pumps are usually vapor compression refrigeration machines, where the evaporator can take heat into the system at low temperatures and the condenser can reject heat from the system at high temperatures. In the heating mode, a heat pump delivers thermal energy from the condenser for space heating and can be combined with solar heating. In the cooling mode, the evaporator extracts heat from the air to be conditioned and rejects heat from the condenser to the atmosphere, with solar energy...

Reckoning Of TiME

In solar energy calculations, apparent solar time (AST) must be used to express the time of day. Apparent solar time is based on the apparent angular motion of the sun across the sky. The time when the sun crosses the meridian of the observer is the local solar noon. It usually does not coincide with the 12 00 o'clock time of a locality. To convert the local standard time (LST) to apparent solar time, two corrections are applied the equation of time and longitude correction. These are analyzed next.

Cell Temperature

As was seen in Section 9.1.3, the performance of the solar cell depends on the cell temperature. This temperature can be determined by an energy balance and considering that the absorbed solar energy that is not converted to electricity is converted to heat, which is dissipated to the environment. Generally, when operating solar cells at elevated temperatures, their efficiency is lowered. In cases where this heat dissipation is not possible, as in building integrated photovoltaics

Solar Dryers

Solar drying is another very important application of solar energy. Solar dryers use air collectors to collect solar energy. Solar dryers are used primarily by the agricultural industry. The purpose of drying an agricultural product is to reduce its moisture content to a level that prevents its deterioration. In drying, two processes take place One is a heat transfer to the product using energy from the heating source, and the other is a mass transfer of moisture from the interior of the product to its surface and from the surface to the surrounding air. There are two types of solar dryers the ones that use solar energy as the only source of heat and the ones that use solar energy as a supplemental source. The airflow can be either natural convection or forced, generated by a fan. In the dryer, the product is heated by the flow of the heated air through the product, by directly exposing the product to solar radiation or a combination of both. Solar energy dryers are classified...

Pool Heating Systems

Solar pool heating systems require no separate storage tank, because the pool itself serves as storage. In most cases, the pool's filtration pump is used to circulate the water through solar panels or plastic pipes. For daylong operation, no automatic controls are required, because the pool usually operates when the sun is shining. If such controls are employed, they are used to direct the flow of filtered water to the collectors only when solar heat is available. This can also be achieved by a simple manually operated valve. Normally, these kinds of solar systems are designed to drain down into the pool when the pump is switched off thus the collectors are inherently freeze protected (ASHRAE, 2007). Recommendations for the design, installation, and commissioning of solar heating systems for swimming pools, using direct circulation of pool water to the solar collectors, are given in the technical report ISO TR 12596 1995 (1995a). The report does not deal with the pool filtration...

Power Tower Systems

As was explained in Chapter 3, Section 3.2.4, power towers or central receiver systems use thousands of individual sun-tracking mirrors, called heliostats, to reflect solar energy onto a receiver located atop a tall tower. The receiver collects the sun's heat in a heat transfer fluid (molten salt) that flows through the receiver. This is then passed optionally to storage and finally to a power conversion system, which converts the thermal energy into electricity and supplies it to the grid. Therefore, a central receiver system is composed of five main components heliostats, including their tracking system receiver heat transport and exchange thermal storage and controls. In many solar power studies, it has been observed that the collector represents the largest cost in the system therefore, an efficient engine is justified to obtain maximum useful conversion of the collected energy. The power tower plants are quite large, generally 10 MWe or more, while the optimum sizes lie between...

General Remarks

The -chart design method is used to quickly estimate the long-term performance of solar energy systems of standard configurations. The input data needed are the monthly average radiation and temperature, the monthly load required to heat a building and its service water, and the collector performance parameters obtained from standard collector tests. A number of assumptions are made for the development of the -chart method. The main ones include assumptions that the systems are well built, system configuration and control are close to the ones considered in the development of the method, and the flow rate in the collectors is uniform. If a system under investigation differs considerably from these conditions, then the -chart method cannot give reliable results. It should also be understood that, because of the nature of the input data used in the -chart method, there are a number of uncertainties in the results obtained. The first uncertainty is related to the meteorological data...

European standards

Solar energy, Vocabulary (ISO 9488 1999). This European-International standard defines basic terms relating to solar energy and has been elaborated in common with ISO. CEN publication date October 1, 1999. The elaboration of these standards has been achieved through a wide European collaboration of all interested parties, such as manufacturers, researchers, testing institutes, and standardization bodies. Furthermore, these standards will promote a fair competition among producers of solar energy equipment on the market, since low-quality low-price products will be easier to be identified by customers, based on uniform test reports comparable throughout Europe.

Exercises

5.2 A 100 m2 light-colored swimming pool is located in a well-sheltered site, where the measured wind speed at 10 m height is 4 m s. The water temperature is 23 C, the ambient air temperature is 15 C, and relative humidity is 55 . There are no swimmers in the pool, the temperature of the make-up water is 20.2 C, and the solar irradiation on a horizontal surface for the day is 19.3 MJ m2-d. If this pool is to be heated by solar energy, how many square meters of collectors would be required if their efficiency is 45

HEAT sToRAGE sYsTEMs

Thermal storage is one of the main parts of a solar heating, cooling, and powergenerating system. Because for approximately half the year any location is in darkness, heat storage is necessary if the solar system must operate continuously. For some applications, such as swimming pool heating, daytime air heating, and irrigation pumping, intermittent operation is acceptable, but most other uses of solar energy require operating at night and when the sun is hidden behind clouds. Usually the design and selection of the thermal storage equipment is one of the most neglected elements of solar energy systems. It should be realized, however, that the energy storage system has an enormous influence on overall system cost, performance, and reliability. Furthermore, the design of the storage Improvement of the utilization of collected solar energy by providing thermal capacitance to alleviate the solar availability and load mismatch and improve the system response to sudden peak loads or loss...

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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