Commercial concentrated solar power plants were first developed in the 1980s, and the 354 MW SEGS CSP installation is the largest solar power plant in the world and is located in the Mojave Desert of California. Other large CSP plants include the Solnova Solar Power Station (150 MW) and the Andasol solar power station (100 MW), both in Spain. The 97 MW Sarnia Photovoltaic Power Plant in Canada, is the world’s largest photovoltaic plant.radiant light and heat from the sun, has been harnessed by humans since ancient times using a range of ever-evolving technologies. Solar radiation, along with secondary solar-powered resources such as wind and wave power, hydroelectricity and biomass, account for most of the available renewable energy on earth. Only a minuscule fraction of the available solar energy is used.
Solar powered electrical generation relies on heat engines and photovoltaics. Solar energy's uses are limited only by human ingenuity. A partial list of solar applications includes space heating and cooling through solar architecture, potable water via distillation and disinfection, daylighting, solar hot water, solar cooking, and high temperature process heat for industrial purposes.To harvest the solar energy, the most common way is to use solar panels.
Solar technologies are broadly characterized as either passive solar or active solar depending on the way they capture, convert and distribute solar energy. Active solar techniques include the use of photovoltaic panels and solar thermal collectors to harness the energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light dispersing properties, and designing spaces that naturally circulate air.
Energy from the Sun
Insolation and Solar radiation
Earth's land surface, oceans and atmosphere absorb solar radiation, and this raises their temperature. Warm air containing evaporated water from the oceans rises, causing atmospheric circulation or convection. When the air reaches a high altitude, where the temperature is low, water vapor condenses into clouds, which rain onto the Earth's surface, completing the water cycle. The latent heat of water condensation amplifies convection, producing atmospheric phenomena such as wind, cyclones and anti-cyclones. Sunlight absorbed by the oceans and land masses keeps the surface at an average temperature of 14 °C. By photosynthesis green plants convert solar energy into chemical energy, which produces food, wood and the biomass from which fossil fuels are derived.
The major automobile manufacturers are producing hybrid automobiles, which are part electric and part gasoline powered. Could these automobiles take another step and obtain some of their fuel from the sun?
Solar Electrical Vehicles has developed a prototype PV Prius to help answer that question. The PV Prius is fitted with a custom molded fiberglass photovoltaic module as shown in Figure 1. Solar Electrical Vehicles has applied for a patent on the PV Prius solar system.
The photovoltaic module is rThe prosecution of a successful Information Warfare (IW) campaign against an industrialised or post industrial opponent will require a suitable set of tools. As demonstrated in the Desert Storm air campaign, air power has proven to be a most effective means of inhibiting the functions of an opponent's vital information processing infrastructure. This is because air power allows concurrent or parallel engagement of a large number of targets over geographically significant areas [SZAFRANSKI95]. While Desert Storm demonstrated that the application of air power was the most practical means of crushing an opponent's information processing and transmission nodes, the need to physically destroy these with guided munitions absorbed a substantial proportion of available air assets in the early phase of the air campaign. Indeed, the aircraft capable of delivery laser guided bombs were largely occupied with this very target set during the first nights of the air battle.
The efficient execution of an IW campaign against a modern industrial or post-industrial opponent will require the use of specialised tools designed to destroy information systems. Electromagnetic bombs built for this purpose can provide, where delivered by suitable means, a very effective tool for this purpose.
2.The EMP Effect
The ElectroMagnetic Pulse (EMP) effect was first observed during the early testing of high altitude airburst nuclear weapons [GLASSTONE64]. The effect is characterised by the production of a very short (hundreds of nanoseconds) but intense electromagnetic pulse, which propagates away from its source with ever diminishing intensity, governed by the theory of electromagnetism. The ElectroMagnetic Pulse is in effect an electromagnetic shock wave. This pulse of energy produces a powerful electromagnetic field, particularly within the vicinity of the weapon burst. The field can be sufficiently strong to produce short lived transient voltages of thousands of Volts (ie kiloVolts) on exposed electrical conductors, such as wires, or conductive tracks on printed circuit boards, where exposed.
It is this aspect of the EMP effect
ated at 215 watts at AM 1.5. The module is connected to a DC-DC converter and peak power tracker. The output of the converter is directly connected to the primary motive NiMh battery.
The daily power production available for charging the Prius primary motive battery is estimated to be between 850 and 1,300 watt-hours. The car uses 150-175 watt-hours per mile. Thus, the expected range per day that the PV Prius would have on solar power alone would be between 5 and 8 miles. Based upon a nominal daily trip length of 28 miles the gasoline consumption of the PV Prius would be reduced by 17% to 29%.
Description of Solar Module
The solar module is fabricated from molded fiberglass to fit on the roof of a standard Toyota Prius automobile. The solar module includes 146 four-inch- square mono-crystalline cells which are rated at 16% nominal efficiency. The cells generate 3.5 A short circuit and 0.57 VDC open circuit. Using a series connection, the PV Cells, which produce 80 VDC, open circuit, 70 VDC at the peak power point with a string current of 3.25 amperes at AM 1.5 conditions.
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Figure 1. Photo of the Prototype PV Prius |
An insulating layer of Tedlar is bonded to the fiberglass with a heat-cure adhesive. The solar cells are series connected and then bonded to the Tedlar insulation with EVA encapsulant. Finally, a Tefzel layer is bonded to the top of the cells for ultraviolet and weather protection. Figure 2 provides a diagram showing the individual layers of the solar module.
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Figure 2. Solar Module Component Layers |
Description of the Interface Electronics
The solar module is connected to a 48 VDC Sealed Lead Acid Battery via a peak power tracking 70 V to 48 V Battery Charger. The Solar Energy stored in the Sealed Lead Acid Battery is in turn delivered to the PV Prius’s primary motive NiMH Battery pack using a DC-DC converter, which steps up the battery voltage from to 48V to 240 V. The Battery Charger and DC-DC converter has a 95% efficiency rating and can provide daily watt-hours and total watt-hour data to the PV Prius’s solar monitoring system. Figure 3 provides a schematic of the electrical components, which are added to a stock Prius to convert it to a PV Prius. Figure 4 shows Lead Acid Battery Box in the trunk of the PV Prius. The Battery Charger and DC-DC converter are contained in a separate compartment in the Battery Box.
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Figure 3 Connection Diagram for Solar Components of the PV Prius |
The ultimate source of much of the world's energy is the sun, which provides the earth with light, heat and radiation. While many technologies derive fuel from one form of solar energy or another, there are also technologies that directly transform the sun's energy into electricity.
The sun bathes the earth in a steady, enormous flow of radiant energy that far exceeds what the world requires for electricity fuel.
There are two different approaches to generate electricity from the sun: photovoltaic (PV) and solar-thermal technologies.
- Initially developed for the space program over 30 years ago, PV, like a fuel cell, relies upon chemical reactions to generate electricity. PV cells are small, square shaped semiconductors manufactured in thin film layers from silicon and other conductive materials. When sunlight strikes the PV cell, chemical reactions release electrons, generating electric current. The small current from individual PV cells, which are installed in modules, can power individual homes and businesses or can be plugged into the bulk electricity grid.
- Solar-thermal technologies are, more or less, a traditional electricity generating technology. They use the sun's heat to create steam to drive an electric generator. Parabolic trough systems, like those operating in southern California, use reflectors to concentrate sunlight to heat oil which in turn creates steam to drive a standard turbine.
Two other solar-thermal technologies are nearing commercial status. Parabolic dish systems concentrate sunlight to heat gaseous hydrogen or helium or liquid sodium to create pressurized gas or steam to drive a turbine to generate electricity. Central receiver systems feature mirrors that reflect sunlight on to a large tower filled with fluid that when heated creates steam to drive a turbine.
Solar Electricity Basics
The three most common types of solar-electric systems are grid-intertied, grid-intertied with battery backup, and off-grid (stand-alone). Each has distinct applications and component needs.Grid Intertied Solar-Electric Systems
Also known as on-grid, grid-tied, or utilityinteractive (UI), grid-intertied solar-electric systems generate solar electricity and route it to the electric utility grid, offsetting a home’s or business’ electrical consumption and, in some instances, even turning the electric meter backwards. Living with a grid-connected solar-electric system is no different than living with grid power, except that some or all of the electricity you use comes from the sun. In many states, the utility credits a homeowner’s account for excess solar electricity produced. This amount can then be applied to other months when the system produces less or in months when electrical consumption is greater. This arrangement is called net metering or net billing. The specific terms of net metering laws and regulations vary from state to state and utility to utility. Consult your local electricity provider or state regulatory agency for their guidelines.
The following illustration includes the primary components of any grid interie solar electric system. See our Solar Electric System Components section for an introduction to the function(s) of each component.
Energy Smarts-Efficiency Gains + Solar Electricity
Creating A Brighter Future
Getting Off the Lifetime Utility Payment Plan: Grid-Connected PV
Grid-Intertied Solar-Electric Systems with Battery Backup
Without a battery bank or generator backup for your gridintertied system, when a blackout occurs, your household will be in the dark, too. To keep some or all of your electric needs (or “loads”) like lights, a refrigerator, a well pump, or computer running even when utility power outages occur, many homeowners choose to install a grid-intertied system with battery backup. Incorporating batteries into the system requires more components, is more expensive, and lowers the system’s overall efficiency. But for many homeowners who regularly experience utility outages or have critical electrical loads, having a backup energy source is priceless.
The following illustration includes the primary components of any grid intertied solar electric system with battery backup. See our Solar Electric System Components section for an introduction to the function(s) of each component.
Eight Years of Solar Electricity: and Counting...
Walking the Talk: Energy Group Gets Solarized
Off-Grid Solar-Electric Systems
Although they are most common in remote locations without utility grid service, off-grid solar-electric systems can work anywhere. These systems operate independently from the grid to provide all of a household’s electricity. That means no electric bills and no blackouts—at least none caused by grid failures. People choose to live off-grid for a variety of reasons, including the prohibitive cost of bringing utility lines to remote homesites, the appeal of an independent lifestyle, or the general reliability a solar-electric system provides. Those who choose to live off-grid often need to make adjustments to when and how they use electricity, so they can live within the limitations of the system’s design. This doesn’t necessarily imply doing without, but rather is a shift to a more conscientious use of electricity.
The following illustration includes the primary components of any off grid solar electric system. See our Solar Electric System Components section for an introduction to the function(s) of each component.
Postmodern PV Pioneers
Solar Comfort in the Idaho Wilderness: Off-Grid PV
All Creatures Under the Sun—My Solar Powered Barn
Green Half-Acre: Off-Grid Country Living – I
Solar power is a form of energy that makes use of the world’s largest energy source: the sun. More than 99% of the world’s available renewable energy is in one way or the other related to solar energy. The sun provides us with 174 petawatts (174,000 terawatts) of energy, of which half (89 petawatts) reaches the Earth surface. Since humanity consumes ‘only’ an estimated 15 Terawatts (2005 figure) of power, we only need to convert a tiny fraction of this free solar energy (~0.00016%) in order to fulfill the energy needs of the global population. Due to increasing environmental and climate awareness, the use of solar power has been growing explosively the past few years. Solar power is now the fastest growing form of energy, far outpacing other renewable energy sources like wind and water. The advantages of solar power are many; it is renewable, silent, emission-free and consistently available. Solar power’s main disavantage is its price; harnessing the power of the sun is still relatively expensive. It is however expected that technological and economical developments will within 10 years put the price of solar power on par with traditional energy sources.
Types of solar power
Throughout the years, humanity has learned to make good use of both the suns light and heat. The following techniques each take a unique approach towards harvesting solar energy. The specific purpose, advantages and disadvantages of each respective technique allow solar power to be broadly applicable:- Solar photovoltaic power: solar photovoltaic power is the most commonly found residential application of solar energy. Solar photovoltaic power makes use of solar panels to convert sunlight into electricity.
- Concentrating solar power: CSP is a type of solar power where parabolic mirrors are used to focus sunlight on a central point or plane. In parabolic through systems, the heat is captured and later converted to current through a steam generator. In a parabolic dish system, the sunlight is focused on a special solar cell, which converts the concentrated sunlight into power.
- Solar thermal energy: solar thermal energy uses a solar collector to capture the heat of the sun. The captured heat then used to heat a building’s water supply, providing warm water and/or central heating.
- Passive solar energy: passive solar energy makes use of architectural ‘tricks’ to enhance a building’s interior climate by allowing the sun to heat the building in appropriate times and places.
Solar power in the United States
Solar power is the most abundantly available form of renewable energy in the United States. However, compared to European countries like Germany and Spain, the market remains vastly underdeveloped. Considering the US is the very birthplace of solar photovoltaics, this is a wasted opportunity in the least. Things are however changing, due to increasing environmental and geopolitical awareness. Last year, total US solar power capacity grew to 8,775 megawatts, a growth of 17%. Note that these figures include solar thermal appliances like pool and space heating. Looking at solar photovoltaics only we see an estimated increase of 342 MW. Compared to Spain (2,460 MW) and Germany (1,860 MW) this figure leaves much to desire. Things are however bound to improve, in large part due to the eight-year extension of the 30% tax credit on solar photovoltaic installations. Finally, the Obama administrations positive stance towards solar power is likely to further propel solar to the center stage of American energy policy.
US solar growth forecast for 2009-2016. Image credit: navigant consulting, inc.
Since utilities now view solar as an opportunity instead of a threat, it is expected that solar energy will reach full grid parity in all states by the year 2015 / 2016. By this time, the whole solar industry is predicted to employ no less than 400,000 “green collar” people. Despite the economic setback of 2008/2009, the future of solar is looking sunny indeed.
Why solar power?
The advantages of solar are numerous:- The environment: apart from production of the necessary equipment, solar power is completely emission-free. A 1 kilowatt peak solar PV system can save up to 450kg (992lbs) of emitted CO2 per year. Solar power is also completely silent.
- Your wallet: with solar power, you are effectively insuring yourself against rising gas and energy prices. The higher the energy price, the faster you redeem your investment. See solar panel profitability for some example calculations. Through net metering, your electric meter will turn backwards if your PV system provides more power than you use at any given moment.
- Politics: the majority of the world’s oil and gas reserves are controlled by countries with less than noble leadership and morale. By reducing oil consumption, you are reducing the income and influence of these states.
- Home value: solar panels are a valued amenity. The increase in home value might well be higher than the price you pay for the installation!
- Independence: if a massive grid failure leaves you without power for an extended time, you can always consider hooking up your PV system to a set of batteries. In the case of solar water heating, you will have a limied supply of warm water even if the gas supply is interrupted.
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Solar Energy
September 09, 2011 @ 6:19:57 AM EST
EPA/Waltraud Grubitzsch
Through the centuries, scientists have found innovative ways to harness the power of the sun — from magnifying glasses to steam engines. Converting more solar power into electricity is high on the political agenda in many countries, amid the push to find domestic energy sources that are less polluting than fossil fuels.
Despite rapid growth in recent years, solar power accounts for less than 1 percent of electricity use in the United States. Solar power is more entrenched in European countries like Spain and Germany, which have promoted its development with strong incentives called feed-in tariffs that require electric utilities to buy solar power at a high, fixed price. In the United States, California is by far the leading solar state.
In the last two years, China has emerged as the dominant player in green energy — especially in solar power. It accounted for at least half the world’s production in 2010, and its market share is rising rapidly. The United States accounted for $1.6 billion of the world’s $29 billion market for solar panels.
But, analysts say, China has achieved this dominance through lavish government subsidies in its solar industry that are detrimental to American companies and other foreign competitors. While most U.S., Japanese and European companies still have a technological edge, China has a cost advantage, industry analysts say. Loans at very low rates from state-owned banks in Beijing, cheap or free land from local and provincial governments across China, huge economies of scale and other cost advantages have transformed China from a minor player in the solar power industry into the main producer of an increasingly competitive source of electricity.
Even with government support, American companies have a hard time competing with foreign producers. In August 2011 three U.S. solar power companies — Solyndra of California, Evergreen Solar of Massachusetts and SpectraWatt of New York — all filed for bankruptcy. In the case of Solyndra, the company had received $527 million in loans from the federal government.
The Energy Department, which approved the company's financing, said China’s subsidies to its solar industry were threatening the ability of Solyndra and other American manufacturers to compete. The price of a solar array, measured by cost per watt of capacity, had fallen 42 percent since December 2010, the agency said. Solar panel prices plunged by 42 percent per kilowatt-hour in the past year as manufacturers have sharply increased capacity, particularly in China. Meanwhile, demand has been somewhat weak in the main markets in the United States and Europe.
Declining global competition has left China’s industry with a dominant sales position, almost three-fifths of the world’s production capacity and rapidly falling costs. China’s Big Three solar power companies — Suntech Power, Yingli Green Energy and Trina Solar — all announced in August 2011 that their sales in the second quarter were up between 33 and 63 percent from a year earlier.
This has drawn concern in Congress, which in January 2011 approved a provision to require the Defense Department to buy only American-made solar panels. The issue of unfair trade practices regarding clean energy also was at the heart of a case the Obama administration filed against China with the World Trade Organization in December 2010.
How It Works
There are several ways to use the sun’s power to generate electricity. One of the most promising is called concentrating solar power. This involves using mirrors to reflect and focus the sun’s rays, providing heat, which in turn helps power a generator. Another is photovoltaic panels, such as the displays on the rooftops of homes and office buildings (some of these displays, especially in California, have recently experienced problems with theft).
Drawbacks and Incentives
The drawback to solar power is that it is expensive to produce: generating power from photovoltaic panels costs more than four times as much as coal, and more than twice what wind power costs. In the United States, the federal government and states have offered a variety of incentives to encourage homeowners and businesses to put panels on their roofs, and for utilities to buy power from large displays. Solar panels produce no energy at night, but that is not a significant problem because the electricity is often most needed in the daytime, when consumers turn on lights and televisions and air-conditioning.
Solar energy is also used to heat water and pools — and of course a properly designed house will optimize the light and heat qualities of as it floods through the windows.
For now, electricity generation from the sun’s rays needs to be subsidized because it requires the purchase of new equipment and investment in evolving technologies. But costs are rapidly dropping. And regulators are still learning how to structure stimulus payments so that they yield a stable green industry that supports itself.
Leading the Solar Race
China’s efforts to dominate renewable energy technologies raise the prospect that the West may someday trade its dependence on oil from the Mideast for a reliance on solar panels, wind turbines and other gear manufactured in China.
The Chinese government charges a renewable energy fee to all electricity users. The fee revenue goes to companies that operate the electricity grid, to make up the cost difference between renewable energy and coal-fired power.
In the United States, power companies frequently face a choice between buying renewable energy equipment or continuing to operate fossil-fuel-fired power plants that have already been built and paid for. In China, power companies have to buy lots of new equipment anyway, and alternative energy is increasingly priced competitively.
But China’s commitment to renewable energy is expensive. Although costs are falling steeply through ma
