Solar power

The term solar power is used to describe a number of methods of harnessing energy from the light of the Sun. It has been present in many traditional building methods for centuries, but has become of increasing interest in developed countries as the environmental costs and limited supply of other power sources such as fossil fuels are realized. It is already in widespread use where other power supplies are absent, such as in remote locations and in space.

Energy from the Sun

The rate at which solar radiation reaches a unit of area in space in the region of the Earth's orbit is 1,366 W/m², as measured upon a surface normal (at a right angle) to the Sun. This number is referred to as the solar constant.Solar Spectra: Standard Air Mass Zero Of the energy received, roughly 19% is absorbed by the atmosphere, while clouds on average reflect a further 35% of the total energy. The generally accepted standard is for peak power of about 1,000 W/m² at sea level. SRRL: An overview of the Solar Radiation Research Laboratory The average power, which is an important quantity when one is considering using solar power, is lower. The image on the right shows the average solar power available on the surface in W/m² after absorption in the atmosphere and reflection by clouds, calculated from satellite cloud data averaged over three years from 1991 to 1993 (24 hours a day). For example, in North America the average power of the solar radiation lies somewhere between 125 and 375 W/m², between 3 and 9 kWh/m²/day. NREL: Dynamic Maps, GIS Data, and Analysis Tools - Solar Maps

It should be noted that this is the maximum available power, and not the power delivered by solar power technology. For example, photovoltaic panels currently have an efficiency of ca. 15% and, hence, a solar panel delivers 19 to 56 W/m² or 0.45-1.35 kWh/m²/day (annual day and night average). The dark disks in the image on the right are an example for the land areas that, if covered with solar panels, would produce slightly more energy in the form of electricity than the total primary energy supply in 2003. International Energy Agency - Homepage That is, solar cells with an assumed 8% efficiency installed in these areas would deliver a bit more energy in the form of electricity than what is currently available from oil, gas, hydropower, nuclear power, etc. combined.

It should also be noted that a recent concern is that of Global dimming, an effect of pollution that is allowing less and less sunlight to reach the Earth's surface. It is intricately linked with pollution particles and Global warming, and is mostly of concern for issues of Global climate change, but is also of concern to proponents of Solar Power due to the existing and potential future decreases in available Solar Energy. The order of magnitude is about 10% less solar energy available at sea level, mostly due to more intense cloud reflections back into outer space. That is, the clouds are whiter, brighter, because the pollution dust serves as vapor-liquid phase change initiation site and generates clouds where otherwise there would be a moisture filled but otherwise clear sky.

After passing through the Earth's atmosphere, most of the sun's energy is in the form of visible and Infrared radiations. Plants use solar energy to create chemical energy through photosynthesis. Humans regularly use this energy burning wood or fossil fuels, or when simply eating the plants.

Classification

A wide range of power technologies exist which can make use of the solar energy reaching Earth. These can be classified in a number of different ways.

Method of energy transformation

Solar energy can be transformed for use elsewhere or utilised directly. Direct solar power involves only one transformation into a usable form. For example:

Sunlight hits a photovoltaic cell (also called a photoelectric cell) creating electricity.
Sunlight hits the dark absorber surface of a solar thermal collector and the surface warms. The heat energy may be carried away by a fluid circuit.
Sunlight strikes a solar sail on a space craft and is converted directly into a force on the sail which causes motion of the craft.
Sunlight strikes a light mill and causes the vanes to rotate, although little practical application has yet been found for this effect.
Sunlight is focused on an externally mounted reflective channel which conducts sunlight into building interiors to supplement lighting.

Indirect solar power involves more than one transformation to reach a usable form. Many other types of power generation are indirectly solar-powered. Some of these are so indirect that they are often excluded from discussion of solar power:

Vegetation uses photosynthesis to convert solar energy to chemical energy, which can later be burned as fuel to generate electricity (see biofuel). Methane (natural gas) and hydrogen may be derived from the biofuel.
Hydroelectric dams and wind turbines are powered by solar energy through its interaction with the Earth's atmosphere and the resulting weather phenomena.
Ocean thermal energy production uses the thermal gradients that are present across ocean depths to generate power. These temperature differences are ultimately due to the energy of the sun.
Energy obtained from oil, coal, and peat originated as solar energy captured by vegetation in the remote geological past and fossilised. Hence the term Fossil fuel. The great time delay between the input of the solar energy and its recovery means these are not practically renewable and therefore not normally classified as solar power.

Complexity of mechanism

Solar power can also be classified as passive or active:

Passive solar systems are systems that do not involve the input of any other forms of energy apart from the incoming sunlight, although (in the case of solar heat through windows) there may be draperies or panels used to reduce nighttime heat losses and thermostatically or manually operated vents (but not fans) to prevent overheating. Passive solar water heaters, for instance, use a thermosiphon and have no pumps. The thermosiphon only operates when hot, to reduce nighttime heat loss. Other space heating systems use a thermal diode to similar effect. Passive solar water distillers may rely upon capillary action to pump water.

Active solar systems use additional mechanisms such as circulation pumps, air blowers or tracking systems which aim collectors at the sun. These mechanisms are typically powered by electricity and may have additional electronic or computerized automatic controls

Focus type

Effective use of solar radiation often requires the radiation (light) to be focused to give a higher intensity beam. Consequently, another scheme for classifying solar power systems is:

Point focus. A parabolic dish or concentrating lens, possibly combined with a heliostat are used to concentrate light at a point (the focus). At the focus there might be placed a high concentration of photovoltaic cells (solar cells) or a thermal energy "receiver", such as those used in Stirling engines.
Line focus. A parabolic trough or a series of long narrow mirrors are used to concentrate light along a line. The SEGS systems in California are an example of this type of system.
Non-focusing systems include solar domestic hot water systems and most photovoltaic cells. These systems have the advantage that they can make use of diffuse solar radiation (which can not be focused). However, if high temperatures are required, this type of system is usually not suitable, because of the lower radiation intensity. Solar water heating is arguably the most practical and economical way to harness "non-focused" solar energy

Advantages and disadvantages of Solar power

Advantages

Solar power is pollution free during use, although the production of the equipment entails some degree of of environmental pollution.

Facilities can operate with little maintenance or intervention after initial setup.

Solar power is becoming more and more economical as costs associated with production decreases, the technology becomes more effective in energy conversion, and the costs of other energy source alternatives increase.

In situations where connection to the electricity grid is difficult or impossible (such as island communities, desolate regions and ocean-going vessels) harvesting solar power is often an economically competitive alternative to energy from traditional sources.

When grid connected, solar electric generation can displace the highest cost electricity during times of peak demand (in many climatic regions), can reduce grid loading, and can eliminate the need for local battery power for use in times of darkness and high local demand; such application is encouraged by net metering. Time-of-use net metering can be highly favorable to small photovoltaic systems.

Grid connected solar electricity can be used locally thus minimizing transmission/distribution losses (approximately 7.2%).

Disadvantages

Solar power at the Earth's surface has a number of disadvantages compared to traditional energy sources:

Intermittency: It is not available at night and is reduced when there is cloud cover, decreasing the reliability of peak output performance or requiring a means of energy storage.

For power grids to stay functional at all times, backup powerplants must be kept 'hot', to replace solar power stations as they stop producing. There is an energy cost to keep plants 'hot', which includes (in the case of coal plants) the burning of coal. Without fundamental changes in the energy system, little fossil power can therefore be displaced, according to critics.

Locations at high latitudes or with frequent cloud cover offer reduced potential for solar power use.

It can only realistically be used to power transport vehicles by converted energy into other form of energy suitable for transport, incurring an energy penalty.

Solar cell technologies produce DC power which must be converted to the AC power when used in currently existing distribution grids. This again incurs an energy penalty (5-10%) which reduces the real energy output of the solar panels.

Types of technologies

Most solar energy used today is harnessed as heat or electricity.

Solar design in architecture

Main articles: Passive solar and Active solar

Solar design can be used to achieve comfortable temperature and light levels with little or no additional energy. This can be through passive solar, where maximising the entrance of sunlight in cold conditions and reducing it in hot weather; and active solar, using additional devices such as pumps and fans to direct warm and cool air or fluid.

Solar heating systems

Solar hot water systems are generally composed of solar thermal collectors, a fluid system to move the heat from the collector to its point of usage, and a reservoir to stock the heat for subsequent use. The systems may be used to heat domestic hot water or a swimming pool, or to provide heat for a building heating circuit. The heat can also be used for industrial applications or as an energy input for other uses such as cooling equipment. Solar hot water systems fall into two categories in terms of their energy impact: low carbon and zero carbon technology. Low carbon solar water heating technology usually uses mains electricity to power the pump which moves the water through the solar panels. This incurs a 10-20% penalty in terms of carbon emissions acording to UK government research. Zero carbon solar does not use mains electricity to circulate the water. Instead it uses either solar photovoltaic electricity which is generated on site or simply the fact that hotter water is less dense and therefore floats upwards in simpler but still effective "thermosyphon" solar heating systems. Until recently solar water heating was viewed as a mature and relatively unchanging technology. This is no longer the case: a variety of new designs, often based on polymers instead of metals and glass are now being developed, mainly in Northern Europe.

Photovoltaic cells

Solar cells, also referred to as photovoltaic cells, are devices or banks of devices that use the photovoltaic effect of semiconductors to generate electricity directly from sunlight. Until recently, their use has been limited due to high manufacturing costs. One cost effective use has been in very low-power devices such as calculators with LCDs. Another use has been in remote applications such as roadside emergency telephones, remote sensing, cathodic protection of pipe lines, and limited "off grid" home power applications. A third use has been in powering orbiting satellites and other spacecraft.

However, the continual decline of manufacturing costs (dropping at 3 to 5% a year in recent years) is expanding the range of cost-effective uses. The average lowest retail cost of a large solar panel declined from $7.50 to $4 per watt between 1990 and 2005. With many jurisdictions now giving tax and rebate incentives, solar electric power can now pay for itself in five to ten years in many places. "Grid-connected" systems - that is, systems with no battery that connect to the utility grid through a special inverter - now make up the largest part of the market. In 2004 the worldwide production of solar cells increased by 60%. 2005 is expected to see large growth again, but shortages of refined silicon have been hampering production worldwide since late 2004.

Concentrating Photovoltaic (CPV) systems

Despite major progress made over the last decade the use of solar panels remains relatively expensive compared to conventional electricity generation. One promising way to reduce cost even further is by using concentrating photovoltaic systems.http://www.earthscan.co.uk/news/article/mps/UAN/486/v/3/sp/332958698966342800322http://thefraserdomain.typepad.com/energy/solarconcentrating_pv/index.htmlhttp://www.nrel.gov/news/press/release.cfm/release_id=10 The idea is to concentrate sunlight by lenses or mirrors onto a small panel of high-efficiency solar cells. That way expensive solar panels are replaced by cheap plastic or glass, thus dramatically reducing the cost per watt. In addition, the amount of solar energy harvested per m² is increased, thus reducing the area needed for generating solar power. High-efficiency cells have been developed for special applications such as satellites and space exploration which require high-performance. GaAs multijunction devices are the most efficient solar cells to date, reaching as high as 39% efficiencyhttp://www.spectrolab.com/. They are also some of the most expensive cells per unit area (up to US$40/cm²).

In Concentrating Photovoltaic systems solar energy is concentrated several hundred times, which increases the solar energy conversion efficiency and reduces the semiconductor area needed per watt of power output. This may be beneficial as an application for multi-junction solar cells, as the high costs and technical challenges of generating large area multi-junction photovoltaics are prohibitive relative to current silicon PV technologies.

Since concentrating photovoltaics requires solar tracking the approach is most suited for large utility scale applications.http://www.nrel.gov/ncpv/new_in_cpv.html Different approaches are being evaluated for that purpose,http://www1.eere.energy.gov/solar/pv_sys_concentrator.html in particular Fresnel lenses,http://www.amonix.com/ parabolic trough concentration systems,http://www.greenhouse.gov.au/renewable/recp/pv/one.htmlhttp://www.pvresources.com/en/concentrator.php and solar dishes.http://www.treehugger.com/files/2006/03/1000_suns_from.php

For examples of concentrating photovoltaic systems suited for rooftop installation on commercial buildings, see the "Sunflower", and the "SunCube" for domestic applications.

Solar thermal electric power plants

Solar thermal energy can be used to heat a fluid to high temperatures and use it to produce electric power.

Solar updraft tower

A Solar updraft tower is a relatively low tech solar thermal power plant where air passes under a very large agricultural glass house (between 2 and 30 km in diameter), is heated by the sun and channeled upwards towards a convection tower. It then rises naturally and is used to drive turbines, which generate electricity.

Energy Tower

An Energy tower is an alternative proposal for the Solar updraft tower. The "Energy Tower" is driven by spraying water at the top of the tower; evaporation of water causes a downdraft by cooling the air thereby increasing its density, driving windturbines at the bottom of the tower. It requires a hot arid climate and large quantities of water (seawater may be used for this purpose) but it does not require the large glass house of the Solar updraft tower.

Solar pond

A solar pond is a relatively low-tech, low cost approach to harvesting solar energy. The principle is to fill a pond with 3 layers of water:

A top layer with a low salt content
An intermediate insulating layer with a salt gradient, which sets up a density gradient that prevents heat exchange by natural convection in the water.
A bottom layer has with a high salt content which reaches a temperature approaching 90 degrees Celsius.

The different densities in the layers due to their salt content prevent convection currents developing which would normally transfer the heat to the surface and then to the air above. The heat trapped in the salty bottom layer can be used for different purposes, such as heating of buildings, industrial processes, or generating electricity.

Solar chemical

Solar chemical refers to a number of possible processes that harness solar energy by absorbing sunlight in a chemical reaction in a way similar to photosynthesis in plants but without using living organisms. No practical process has yet emerged.
A promising approach is to use focused sunlight to provide the energy needed to split water into its constituent hydrogen and oxygen in the presence of a metallic catalyst such as zinc.IsraCast: ZINC POWDER WILL DRIVE YOUR HYDROGEN CARWired News: Sunlight to Fuel Hydrogen FutureSolar Technology Laboratory: SynMet

While metals, such as zinc, have been shown to drive photoelectrolysis of water, more intensive research has focused on semiconductors. Most research has examined tranisition metal compounds, in particular titania, titanates, niobates, tantalates, and many more. Unfortunately, these materials exhibit very low efficiencies, because they require ultraviolet light to drive the photoelectrolysis of water. Current materials also require an electrical voltage bias for the hydrogen and oxygen gas to evolve from the surface, another disadvantage. Current research is focusing on the developement of materials capable of the same water splitting reaction using lower energy visible light.

It is also possible to use solar energy to drive industrial chemical processes without a requirement for fossil fuel.

Phytochemical energy storage (Biofuels)

See Biofuels and Biodiesel The oil in plant seeds, in chemical terms, very closely resembles that of petroleum. Many, since the invention of the Diesel engine, have been using this form of captured solar energy as a fuel comparable to petrodiesel - for functional use in any diesel engine or generator and known as Biodiesel. A 1998 joint study by the U.S. Department of Energy (DOE) and the U.S. Department of Agriculture (USDA) traced many of the various costs involved in the production of biodiesel and found that overall, it yields 3.2 units of fuel product energy for every unit of fossil fuel energy consumed. Life Cycle Inventory of Biodiesel and Petroleum Diesel for Use in an Urban Bus Other Biofuels include ethanol, wood for stoves, ovens and furnaces, and methane gas produced from biofuels through chemical processes.

Solar cooking

A solar box cooker traps the Sun's power in an insulated box; such boxes have been successfully used for cooking, pasteurization and fruit canning. Solar cooking is helping many developing countries, both reducing the demands for local firewood and maintaining a cleaner environment for the cooks. The first known western solar oven is attributed to Horace de Saussure.

Solar lighting

The interior of a building can be lit during daylight hours using fiber optic light pipes connected to a parabolic collector mounted on the roof. The manufacturer claims this gives a more natural interior light and can be used to reduce the energy demands of electric lighting. Sunlight Direct Products

Energy storage

For a stand-alone system, some means must be employed to store the collected energy for use during hours of darkness or cloud cover. The following list includes both mature and immature techniques:

Electrochemically in batteries
Cryogenic liquid air or nitrogen
Compressed air in a cylinder
Flywheel energy storage
Hydrogen produced by electrolysis of water and then available for pollution free combustion
Hydraulic accumulator
Pumped-storage hydroelectricity
Molten saltSolar Tres Project
Superconducting magnetic energy storages

Storage always has an extra stage of energy conversion, with consequent energy losses, greatly increasing capital costs. One way around this is to export excess power to the power grid, drawing it back when needed. This appears to use the power grid as a battery but in fact is relying on conventional energy production through the grid during the night. However, since the grid always has a positive outflow, the result is exactly the same.

Electric power costs are highly dependant on the consumption per time of day, since plants must be built for peak power (not average power). Expensive gas-fired "peaking generators" must be used when base capacity is insufficient. Fortunately for solar, solar capacity parallels energy demand -since much of the electricity is for removing heat produced by too much solar energy (air conditioners)! This is less true in the winter. Wind power complements solar power since it can produce energy when there is no sunlight.

Deployment of solar power to energy grids

Deployment of solar power depends largely upon local conditions and requirements. But as all industrialised nations share a need for electricity, it is clear that solar power will increasingly be used to supply a cheap, reliable electricity supply.

Several experimental photovoltaic (PV) power plants of 300 to 600 kW capacity are connected to electricity grids in Europe and the U.S. Other major research is investigating economic ways to store the energy which is collected from the sun's rays during the day.

Africa

Africa is home to the over 9 million km² Sahara desert, whose overall capacity — assuming 50 MW/km² day/night/cloud average with 15% efficient photovoltaic panels — is over 450 TW, or over 4,000,000 terawatt-hours per year. The current global energy consumption by humans, including all oil, natural gas, coal, nuclear, and hydroelectric, is pegged at about 13 TW.

Australia

The largest solar power station in Australia is the 400kWp array at Singleton, New South Wales. Other significant solar arrays include the 220 kWp array on the Anangu Pitjantjatjara Lands in South Australia, the 200kWp array at Queen Victoria Market in Melbourne and the 160kWp array at Kogarah Town Square in Sydney. A building-integrated photo voltaic (BIPV) installation of 60kW in Brisbane (at the Hall-Chadwick building) has an uninterruptible power supply (UPS) which gives around 10-15 minutes worth of emergency power in the event of the loss of electricity supply. Any power not used by the UPS is connected to the grid and goes towards reducing the building's overall power bills. Numerous smaller arrays have been established, mainly in remote areas where solar power is cost-competitive with diesel power.AGO - Renewable Energy - Power Stations

Asia

As of 2004, Japan had 1200 MWe installed. Japan currently consumes about half of worldwide production of solar modules, mostly for grid connected residential applications.

In terms of overall installed PV capacity, India comes fourth after Japan, Germany, and the United States (Indian Ministry of Non-conventional Energy Sources 2002). Government support and subsidies have been major influences in its progress.Solar energy heats up India is Rapidly Developing Solar Energy via Photovoltaic & Thermal Systems India's very long-term solar potential may be unparalleled in the world because it is one of the few places with an ideal combination of both high solar power reception and a large consumer base in the same place. India's theoretical solar potential is about 5000 TW·h per year (i.e. 600 GW), far more than its current total consumption.

In 2005, the Israeli government announced an international contract for building a 100 MW solar power plant to supply the electricity needs of more than 200,000 Israelis living in southern Israel. The plan may eventually allow the creation of a gigantic 500 MW power plant, making Israel a leader in solar power production.IsraCast: Technology in Israel

Europe

The 10 megawatt Bavaria Solarpark in Germany is the world's largest solar electric system, covering 25 hectares (62 acres) with 57,600 photovoltaic panels. World's Largest Solar Electric System - PowerLight

A large solar PV plant is planned for the island of Crete. Research continues into ways to make the actual solar collecting cells less expensive and more efficient.

A large parabolic reflector solar furnace is located in the Pyrenees at Odeillo, France. It is used for various research purposes.Les Fours solaires Another site is the Loser in Austria.

The Plataforma Solar de Almería (PSA) in Spain, part of the Center for Energy, Environment and Technological Research (CIEMAT), is the largest center for research, development, and testing of concentrating solar technologies in Europe.Plataforma Solar de Almería - Facilities and Infraestructure

In the United Kingdom, the tallest building in Manchester, the CIS Tower, was clad in photovoltaic panels at a cost of £5.5 million and started feeding electricity to the national grid on November 2005.Building converts to solar power

On April 27, 2006, GE Energy Financial Services, PowerLight Corporation and Catavento Lda announced that they will build the world’s largest solar photovoltaic power project. The 11-megawatt solar power plant, comprising 52,000 photovoltaic modules, will be built at a single site in Serpa, Portugal, 200 kilometers (124 miles) southeast of Lisbon in one of Europe’s sunniest areas. WORLD’S LARGEST SOLAR PHOTOVOLTAIC POWER PLANT TO BE BUILT

North America

In some areas of the United States, solar electric systems are already competitive with utility systems. As of 2005, there is a list of technical conditions that factor into the economic feasibility of going solar: the amount of sunlight that the area receives; the purchase cost of the system; the ability of the system owner to sell power back to the electric grid; and most important, the competing power prices from the local utility. For example, a photovoltaic system installed in Boston, Massachusetts, produces 25% less electricity than it would in Albuquerque, New Mexico, but yields roughly the same savings on utility bills since electricity costs more in Boston.

In addition to these considerations, many states and regions offer substantial incentives to improve the economics for potential consumers. Congress recently adopted the first federal tax breaks for residential solar since 1985 -- temporary credits available for systems installed in 2006 or 2007. Homeowners can claim one federal credit of up to $2,000 to cover 30% of a photovoltaic system's cost and another 30% credit of up to $2,000 for a solar thermal system. Fifteen states also offer tax breaks for solar, and two dozen states offer direct consumer rebates.Database of State Incentives for Renewable Energy (DSIRE)

Solar One is a pilot solar-thermal project in the Mojave Desert near Barstow, California. It uses heliostats, and molten salts storage technology, to achieve longer periods of power generation.

Solar Two, also near Barstow, has now built and elaborated on the success of Solar One. It was an R&D project in Barstow, California, financed by the US federal Department of Energy. Solar Two used liquid salts as a storage medium in order to continue to provide energy for much of the time when sunlight is not available. Its success has lead to the larger Solar Tres project in Spain.

On August 11, 2005, Southern California Edison announced an agreement to purchase solar powered Stirling engines from Stirling Energy Systems over a twenty year period and in quantities (20,000 units) sufficient to generate 500 megawatts of electricity.World's largest solar installation to use Stirling engine technology These systems — to be installed on a 4,500 acre (18 km²) solar farm — will use mirrors to direct and concentrate sunlight onto the engines which will drive generators. Less than a month later, Stirling Energy Systems announced another agreement with San Diego Gas & Electric to provide between 300 and 900 megawatts of electricity.World's Largest Solar Energy Farm to be built in Southern California

The world's largest solar power plant is located in the Mojave Desert. SolelSolel, an Israeli company, operates the plant, which consists of 1000 acres (4 km²) of solar reflectors. This plant produces 90% of the world's commercially produced solar power.

On January 12, 2006, the California Public Utilities Commission approved the California Solar Incentive ProgramCalifornia Solar Incentive Program, a comprehensive $2.8 billion program that provides incentives toward solar development over 11 years.

Deployment of Solar power in transport

Development of a practical solar powered car has been an engineering goal for twenty years. The center of this development is the World Solar Challenge, a biannual solar powered car race over 3021 km through central Australia from Darwin to Adelaide. The race's stated objective is to promote research into solar-powered cars. Teams from universities and enterprises participate. In 1987 when it was founded the winner's average speed was 67 km/h. By the 2005 race this had increased to a record average speed of 103 km/h.

World solar power production

Total peak power of installed solar panels is around 5,300 MW as of the end of 2005. (IEA statistics appear to be underreported: they report 2,600 MW as of 2004, which with 1,700 installed in 2005 would be a cumulative total of 4,300 for 2005). These figures include only photovoltaic generated power and not that produced by other solar means. Inclusion of the U.S.'s solar reflector plants would double its total, putting it at the level of the second place country on the list.

Solar Heating

To solar heat things, water runs through pipes in the heating panel, where the suns heat energy is sourced. In the exchanger it the sun to the house. It gives electricity for washing or room heating.

|+ Installed PV Power as of the end of 2004 Total photovoltaic power installed in IEA PVPS countries |- ! rowspan=3 style="background:#efefef; border-bottom:3px solid grey;" | Country ! colspan="5" style="background:#efefef;" | PV Capacity |- ! colspan="3" style="background:#efefef;" | Cumulative ! colspan="2" style="background:#efefef;" | Installed in 2004 |- ! style="background:#efefef; border-bottom:3px solid grey;" | Off-grid PV ^* ! style="background:#efefef; border-bottom:3px solid grey;" | Grid-connected ^* ! style="background:#efefef; border-bottom:3px solid grey;" | Total ^* ! style="background:#efefef; border-bottom:3px solid grey;" | Total ^* ! style="background:#efefef; border-bottom:3px solid grey;" | Grid-tied ^* |- | Japan || 84,245 || 1,047,746 || 1,131,991 || 272,368 || 267,016 |- | Germany || 26,000 || 768,000 || 794,000 || 363,000 || 360,000 |- | United States || 189,600 || 175,600 || 365,200 || 90,000 || 62,000 |- | Australia || 48,640 || 6,760 || 52,300 || 6,670 || 780 |- | Netherlands || 4,769 || 44,310 || 49,079 || 3,162 || 3,071 |- | Spain || 14,000 || 23,000 || 37,000 || 10,000 || 8,460 |- | Italy || 12,000 || 18,700 || 30,700 || 4,700 || 4,400 |- | France || 18,300 || 8,000 || 26,300 || 5,228 || 4,183 |- | Switzerland || 3,100 || 20,000 || 23,100 || 2,100 || 2,000 |- | Austria || 2,687 || 16,493 || 19,180 || 2,347 || 1,833 |- | Mexico || 18,172 || 10 || 18,182 || 1,041 || 0 |- | Canada || 13,372 || 512 || 13,884 || 2,054 || 107 |- | Korea || 5,359 || 4,533 || 9,892 || 3,454 || 3,106 |- | United Kingdom || 776 || 7,386 || 8,164 || 2,261 || 2,197 |- | Norway || 6,813 || 75 || 6,888 || 273 || 0 |- |}

Large PV power plants

This list shows the largest photovoltaic plants in the world. For comparison, the largest solar plant, the solar reflector-based SEGS in California produces 350 MW and the largest nuclear power plants generate more than 1,000 MW.

|+ World's largest PV power plants World's largest photovoltaic power plants |- ! style="background:#efefef; border-bottom:3px solid grey;" | DC Peak Power ! style="background:#efefef; border-bottom:3px solid grey;" | Location ! style="background:#efefef; border-bottom:3px solid grey;" | Description ! style="background:#efefef; border-bottom:3px solid grey;" | MW·h/year |- | 11 MW* || Serpa, Portugal || 52,000 solar modules || Press Release |- | 6.3 MW || Mühlhausen, Germany || 57,600 solar modules || 6,750 MW·h |- | 5 MW || Bürstadt, Germany || 30,000 BP solar modules || 4,200 MW·h |- | 5 MW || Espenhain, Germany || 33,500 Shell solar modules || 5,000 MW·h |- | 4.59 MW || Springerville, AZ, USA || 34,980 BP solar modules || 7,750 MW·h |- | 4 MW || Geiseltalsee, Merseburg, Germany || 25,000 BP solar modules || 3,400 MW·h |- | 4 MW || Gottelborn, Germany || 50,000 solar modules (when completed) || 8,200 MW·h (when completed) |- | 4 MW || Hemau, Germany || 32,740 solar modules || 3,900 MW·h |- | 3.9 MW || Rancho Seco, CA, USA || n.a. || n.a. |- | 3.3 MW || Dingolfing, Germany || Solara, Sharp and Kyocera solar modules || 3,050 MW·h |- | 3.3 MW || Serre, Italy || 60,000 solar modules || n.a. |}

* Under construction, as of July 2006.

Corporate ownership of solar technology

In 1979 Ray Fleece described how US corporations prevented the growth of the solar industry in his book The Sun Betrayed: Report on the Corporate Seizure of U.S. Solar Energy Development which provides "This is a disturbing history of the collusion between federal and corporate energy executives to control the development of solar energy."

References

External links

Solar Energy Industries Association is the national trade association for the US solar energy industry and has information on current commercial technologies and market developments.
Direct solar U.S. Department of Energy: Energy Efficiency and Renewable Energy - Thermal water splitting
U.S. Department of Energy: Energy Efficiency and Renewable Energy Solar History Timeline
National Renewable Energy Laboratory: Concentrating Solar Power (CSP)
ESTIF - European Solar Thermal Industry organization (statistics, market situation)
Library of public domain images of operational Solar Power projects from the World-wide Information System for Renewable Energy (WIRE).
Solar Facts - Information about all aspects of solar
Solar Power for Everyone - DIY Solar power resources.
Solar Power Wireless Mesh DIY Wireless Mesh Solar Experiment

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