Photovoltaics: Difference between revisions
No edit summary |
|||
| Line 98: | Line 98: | ||
Design studies of large solar power collection satellites have been conducted for decades. The idea was first proposed by Peter Glaser, then of Arthur D. Little Inc; [[NASA]] conducted a long series of engineering and economic feasibility studies in the 1970s, and interest has revived in first years of the 21st century. |
Design studies of large solar power collection satellites have been conducted for decades. The idea was first proposed by Peter Glaser, then of Arthur D. Little Inc; [[NASA]] conducted a long series of engineering and economic feasibility studies in the 1970s, and interest has revived in first years of the 21st century. |
||
From a practical economic viewpoint, dozens of issues would have to be solved before space-based solar power will be a feasible alternative. A key issue for such satellites appears to be the launch cost, which so far makes space-based solar power at least 100 times more expensive than terrestrial solar power. Additional considerations will include controlling and pointing enormous flexible arrays in space, beaming the energy to large terrestrial receivers so as not to fry all living things in the path of the beam, and launching the thousands of heavy-lift vehicles per year it would take to build a significant energy capacity in space. Challenges such as developing space-based assembly techniques for the flexible arrays that would cover thousands of hectares make the construction of the International Space Station seem like child's play, but they seem to be less a hurdle than the capital cost. Reductions in photovoltaic cell costs or efficiency increases will not help, as the same improvements make terrestrial-based solar power more economical as well. |
From a practical economic viewpoint, dozens of issues would have to be solved before space-based solar power will be a feasible alternative. A key issue for such satellites appears to be the launch cost, which so far makes space-based solar power at least 100 times more expensive than terrestrial solar power. Additional considerations will include controlling and pointing enormous flexible arrays in space, beaming the energy to large terrestrial receivers so as not to fry all living things in the path of the beam, and launching the thousands of heavy-lift vehicles per year it would take to build a significant energy capacity in space. Challenges such as developing space-based assembly techniques for the flexible arrays that would cover thousands of hectares make the construction of the International Space Station seem like child's play, but they seem to be less a hurdle than the capital cost. Reductions in photovoltaic cell costs or efficiency increases will not help, as the same improvements make terrestrial-based solar power more economical as well. hi. |
||
==Performance== |
==Performance== |
||
Revision as of 15:49, 5 April 2011
Photovoltaics (PV) is a method of generating electrical power by converting solar radiation into direct current electricity using semiconductors that exhibit the photovoltaic effect. Photovoltaic power generation employs solar panels composed of a number of cells containing a photovoltaic material. Materials presently used for photovoltaics include monocrystalline silicon, polycrystalline silicon, amorphous silicon, cadmium telluride, and copper indium selenide/sulfide.[1] Due to the growing demand for renewable energy sources, the manufacturing of solar cells and photovoltaic arrays has advanced considerably in recent years.[2][3][4]
As of 2010, solar photovoltaics generates electricity in more than 100 countries and, while yet comprising a tiny fraction of the 4.8 TW total global power-generating capacity from all sources, is the fastest growing power-generation technology in the world. Between 2004 and 2009, grid-connected PV capacity increased at an annual average rate of 60 percent, to some 21 GW.[5] Such installations may be ground-mounted (and sometimes integrated with farming and grazing)[6] or built into the roof or walls of a building, known as Building Integrated Photovoltaics or BIPV for short.[7] Off-grid PV accounts for an additional 3–4 GW.[5]
Driven by advances in technology and increases in manufacturing scale and sophistication, the cost of photovoltaics has declined steadily since the first solar cells were manufactured.[8] Net metering and financial incentives, such as preferential feed-in tariffs for solar-generated electricity, have supported solar PV installations in many countries.
Photovoltaic effect
The photovoltaic effect is the creation of a voltage (or a corresponding electric current) in a material upon exposure to light. Though the photovoltaic effect is directly related to the photoelectric effect, the two processes are different and should be distinguished. In the photoelectric effect, electrons are ejected from a material's surface upon exposure to radiation of sufficient energy. The photovoltaic effect is different in that the generated electrons are transferred between different bands (i.e., from the valence to conduction bands) within the material, resulting in the buildup of a voltage between two electrodes.[9]
In most photovoltaic applications the radiation is sunlight and for this reason the devices are known as solar cells. In the case of a p-n junction solar cell, illuminating the material creates an electric current as excited electrons and the remaining holes are swept in different directions by the built-in electric field of the depletion region.[10]
The photovoltaic effect was first observed by Alexandre-Edmond Becquerel in 1839.[11][12]
Solar cells
Photovoltaics are best known as a method for generating electric power by using solar cells to convert energy from the sun into electricity. The photovoltaic effect refers to photons of light knocking electrons into a higher state of energy to create electricity. The term photovoltaic denotes the unbiased operating mode of a photodiode in which current through the device is entirely due to the transduced light energy. Virtually all photovoltaic devices are some type of photodiode.
Solar cells produce direct current electricity from sun light, which can be used to power equipment or to recharge a battery. The first practical application of photovoltaics was to power orbiting satellites and other spacecraft, but today the majority of photovoltaic modules are used for grid connected power generation. In this case an inverter is required to convert the DC to AC. There is a smaller market for off-grid power for remote dwellings, boats, recreational vehicles, electric cars, roadside emergency telephones, remote sensing, and cathodic protection of pipelines.
Cells require protection from the environment and are usually packaged tightly behind a glass sheet. When more power is required than a single cell can deliver, cells are electrically connected together to form photovoltaic modules, or solar panels. A single module is enough to power an emergency telephone, but for a house or a power plant the modules must be arranged in multiples as arrays. Although the selling price of modules is still too high to compete with grid electricity in most places[citation needed], significant financial incentives in Japan and then Germany, Italy, Greece and France triggered a huge growth in demand, followed quickly by production. In 2008, Spain installed 45% of all photovoltaics, but a change in law limiting the feed-in tariff is expected to cause a precipitous drop in the rate of new installations there, from an extra 2.5 GW in 2008, to an expected additional 375 MW in 2009.[13]
A significant market has emerged in off-grid locations for solar-power-charged storage-battery based solutions. These often provide the only electricity available.[14] The first commercial installation of this kind was in 1966 on Ogami Island in Japan to transition Ogami Lighthouse from gas torch to fully self-sufficient electrical power.
Due to the growing demand for renewable energy sources, the manufacture of solar cells and photovoltaic arrays has advanced dramatically in recent years.[2][3][4]
Photovoltaic production has been increasing by an average of more than 20 percent each year since 2002, making it the world’s fastest-growing energy technology.[15][16] At the end of 2009, the cumulative global PV installations surpassed 21 GW.[16] Roughly 90% of this generating capacity consists of grid-tied electrical systems. Such installations may be ground-mounted (and sometimes integrated with farming and grazing) [6] or built into the roof or walls of a building, known as Building Integrated Photovoltaics or BIPV for short.[7] Solar PV power stations today have capacities ranging from 10–60 MW although proposed solar PV power stations will have a capacity of 150 MW or more.[1]
World solar photovoltaic (PV) installations were 2.826 GW peak (GWp) in 2007, and 5.95 GW in 2008, 7.5 GW in 2009, and 18.2 GW in 2010.[17][18][19][20] The three leading countries (Germany, Japan and the US) represent nearly 89% of the total worldwide PV installed capacity.
Germany installed a record 3.8 GW of solar PV in 2009;[21] in contrast, the US installed about 500 MW in 2009. The previous record, 2.6 GW, was set by Spain in 2008. Germany was also the fastest growing major PV market in the world from 2006 to 2007 industry observers speculate that Germany could install more than 4.5 GW in 2010.[21][22] The German PV industry generates over 10,000 jobs in production, distribution and installation. By the end of 2006, nearly 88% of all solar PV installations in the EU were in grid-tied applications in Germany.[2]
Photovoltaic power capacity is measured as maximum power output under standardized test conditions (STC) in "Wp" (Watts peak).[23] The actual power output at a particular point in time may be less than or greater than this standardized, or "rated," value, depending on geographical location, time of day, weather conditions, and other factors.[24] Solar photovoltaic array capacity factors are typically under 25%, which is lower than many other industrial sources of electricity.[25] Therefore the 2008 installed base peak output would have provided an average output of 3.04 GW (assuming 20% × 15.2 GWp). This represented 0.15 percent of global demand at the time.[26]
The EPIA/Greenpeace Advanced Scenario shows that by the year 2030, PV systems could be generating approximately 1.8 TW of electricity around the world. This means that, assuming a serious commitment is made to energy efficiency, enough solar power would be produced globally in twenty-five years’ time to satisfy the electricity needs of almost 14% of the world’s population.[27]
Current developments
Photovoltaic panels based on crystalline silicon modules are being partially replaced in the market by panels that employ thin-film solar cells (CdTe[28] CIGS,[29] amorphous Si,[30] microcrystalline Si), which are rapidly growing and are expected to account for 31 percent of the global installed power by 2013.[31] Other developments include casting wafers instead of sawing,[32] concentrator modules, 'Sliver' cells, and continuous printing processes. Due to economies of scale solar panels get less costly as people use and buy more — as manufacturers increase production to meet demand, the cost and price is expected to drop in the years to come. By early 2006, the average cost per installed watt for a residential sized system was about USD 7.50 to USD 9.50, including panels, inverters, mounts, and electrical items.[33]
In 2006 investors began offering free solar panel installation in return for a 25 year contract, or Power Purchase Agreement, to purchase electricity at a fixed price, normally set at or below current electric rates.[34][35] It is expected that by 2009 over 90% of commercial photovoltaics installed in the United States will be installed using a power purchase agreement.[36] An innovative financing arrangement in Berkeley, California, funded by grants from the United States Environmental Protection Agency and the Bay Area Air Quality Management District, lends money to a homeowner for solar system, to be repaid via an additional tax assessment on the property which remains in place for 20 years. This allows installation of the solar system at "relatively little up-front cost to the property owner."[37]
A San Jose based company, Sunpower, produces cells that have an energy conversion ratio of 19.5%, well above the market average of 12–18%.[38] However, advances past this efficiency mark are being pursued in academia and research and development labs with efficiencies of 42% achieved at the University of Delaware in conjunction with DuPont by means of concentration of light[39] The highest efficiencies achieved without concentration include Sharp Corporation at 35.8% using a proprietary triple-junction manufacturing technology in 2009,[40] and Boeing Spectrolab (40.7% also using a triple layer design). A March 2010 experimental demonstration of a design by a Caltech group which has an absorption efficiency of 85% in sunlight and 95% at certain wavelengths is claimed to have near perfect quantum efficiency.[41] However, absorption efficiency should not be confused with the sunlight-to-electricity conversion efficiency.
Applications
Power stations
Many solar photovoltaic power stations have been built, mainly in Europe.[42] As of December 2010, the largest photovoltaic (PV) power plants in the world are the Sarnia Photovoltaic Power Plant (Canada, 97 MW), Montalto di Castro Photovoltaic Power Station (Italy, 84.2 MW), Finsterwalde Solar Park (Germany, 80.7 MW), Rovigo Photovoltaic Power Plant (Italy, 70 MW), Olmedilla Photovoltaic Park (Spain, 60 MW), the Strasskirchen Solar Park (Germany, 54 MW), and the Lieberose Photovoltaic Park (Germany, 53 MW).[42] Larger power stations are under construction, some proposed will have a capacity of 150 MW or more.[1] A planned installation in China will produce 2000 megawatts at peak. [43]
Many of these plants are integrated with agriculture and some use innovative tracking systems that follow the sun's daily path across the sky to generate more electricity than conventional fixed-mounted systems. There are no fuel costs or emissions during operation of the power stations.
In buildings
Photovoltaic arrays are often associated with buildings: either integrated into them, mounted on them or mounted nearby on the ground.
Arrays are most often retrofitted into existing buildings, usually mounted on top of the existing roof structure or on the existing walls. Alternatively, an array can be located separately from the building but connected by cable to supply power for the building. In 2010, more than four-fifths of the 9,000 MW of solar PV operating in Germany was installed on rooftops.[21]
Building-integrated photovoltaics (BIPV) are increasingly incorporated into new domestic and industrial buildings as a principal or ancillary source of electrical power.[44] Typically, an array is incorporated into the roof or walls of a building. Roof tiles with integrated PV cells are also common.
The power output of photovoltaic systems for installation in buildings is usually described in kilowatt-peak units (kWp).
In transport
PV has traditionally been used for electric power in space. PV is rarely used to provide motive power in transport applications, but is being used increasingly to provide auxiliary power in boats and cars. A self-contained solar vehicle would have limited power and low utility, but a solar-charged vehicle would allow use of solar power for transportation. Solar-powered cars have been demonstrated.[45]
Standalone devices
Until a decade or so ago, PV was used frequently to power calculators and novelty devices. Improvements in integrated circuits and low power LCD displays make it possible to power such devices for several years between battery changes, making PV use less common. In contrast, solar powered remote fixed devices have seen increasing use recently in locations where significant connection cost makes grid power prohibitively expensive. Such applications include water pumps,[46] parking meters,[47] emergency telephones,[48] trash compactors,[49] temporary traffic signs, and remote guard posts & signals.
Rural electrification
Developing countries where many villages are often more than five kilometers away from grid power have begun using photovoltaics. In remote locations in India a rural lighting program has been providing solar powered LED lighting to replace kerosene lamps. The solar powered lamps were sold at about the cost of a few month's supply of kerosene.[50][51] Cuba is working to provide solar power for areas that are off grid.[52] These are areas where the social costs and benefits offer an excellent case for going solar though the lack of profitability could relegate such endeavors to humanitarian goals.
Solar roadways
A 45 mi (72 km) section of roadway in Idaho is being used to test the possibility of installing solar panels into the road surface, as roads are generally unobstructed to the sun and represent about the percentage of land area needed to replace other energy sources with solar power.[53]
Solar Power satellites
Design studies of large solar power collection satellites have been conducted for decades. The idea was first proposed by Peter Glaser, then of Arthur D. Little Inc; NASA conducted a long series of engineering and economic feasibility studies in the 1970s, and interest has revived in first years of the 21st century.
From a practical economic viewpoint, dozens of issues would have to be solved before space-based solar power will be a feasible alternative. A key issue for such satellites appears to be the launch cost, which so far makes space-based solar power at least 100 times more expensive than terrestrial solar power. Additional considerations will include controlling and pointing enormous flexible arrays in space, beaming the energy to large terrestrial receivers so as not to fry all living things in the path of the beam, and launching the thousands of heavy-lift vehicles per year it would take to build a significant energy capacity in space. Challenges such as developing space-based assembly techniques for the flexible arrays that would cover thousands of hectares make the construction of the International Space Station seem like child's play, but they seem to be less a hurdle than the capital cost. Reductions in photovoltaic cell costs or efficiency increases will not help, as the same improvements make terrestrial-based solar power more economical as well. hi.
Performance
Temperature
Generally, temperatures above room temperature reduce the performance of photovoltaics.[54]
Optimum Orientation of Solar Panels
For best performance, terrestrial PV systems aim to maximize the time they face the sun. Solar trackers aim to achieve this by moving PV panels to follow the sun. The increase can be by as much as 20% in winter and by as much as 50% in summer. Static mounted systems can be optimized by analysis of the Sun path. Panels are often set to latitude tilt, an angle equal to the latitude, but performance can be improved by adjusting the angle for summer or winter.
Advantages
The 89,000 TW of sunlight reaching the Earth's surface is plentiful – almost 6,000 times more than the 15 TW equivalent of average power consumed by humans.[55] Additionally, solar electric generation has the highest power density (global mean of 170 W/m²) among renewable energies.[55]
Solar power is pollution-free during use. Production end-wastes and emissions are manageable using existing pollution controls. End-of-use recycling technologies are under development [56] and policies are being produced that encourage recycling from producers.[57]
PV installations can operate for many years with little maintenance or intervention after their initial set-up, so after the initial capital cost of building any solar power plant, operating costs are extremely low compared to existing power technologies.
Solar electric generation is economically superior where grid connection or fuel transport is difficult, costly or impossible. Long-standing examples include satellites, island communities, remote locations and ocean vessels.
When grid-connected, solar electric generation replaces some or all of the highest-cost electricity used during times of peak demand (in most climatic regions). This can reduce grid loading, and can eliminate the need for local battery power to provide for use in times of darkness. These features are enabled by net metering. Time-of-use net metering can be highly favorable, but requires newer electronic metering, which may still be impractical for some users.
Grid-connected solar electricity can be used locally thus reducing transmission/distribution losses (transmission losses in the US were approximately 7.2% in 1995).[58]
Compared to fossil and nuclear energy sources, very little research money has been invested in the development of solar cells, so there is considerable room for improvement. Nevertheless, experimental high efficiency solar cells already have efficiencies of over 40% in case of concentrating photovoltaic cells [59] and efficiencies are rapidly rising while mass-production costs are rapidly falling.[60]
Disadvantages
Photovoltaics are costly to install. While the modules are often warranteed for upwards of 20 years, much of the investment in a home-mounted system may be lost if the home-owner moves and the buyer puts less value on the system than the seller.[notes 1]
Solar electricity is more expensive than most other forms of small-scale alternative energy production.[citation needed] Without governments mandating "feed-in tariffs"[notes 2] for green solar energy, solar PV is in less affordable to homeowners than solar hot water or solar space heating.[notes 3]
Solar electricity is not produced at night and is much reduced in cloudy conditions. Therefore, a storage or complementary power system is required.[notes 4]
Solar electricity production depends on the limited power density of the location's insolation. Average daily output of a flat plate collector at latitude tilt in the contiguous US is 3–7 kilowatt·h/m²/day[notes 5][61][62][63] and on average lower in Europe. hi
Solar cells produce DC which must be converted to AC (using a grid tie inverter) when used in existing distribution grids. This incurs an energy loss of 4–12%.[64]
See also
- Active solar
- American Solar Energy Society
- Carbon nanotubes in photovoltaics
- Concentrated photovoltaics
- Cost of electricity by source
- Deployment of solar power to energy grids
- Grid-tied electrical system
- History of photovoltaics
- List of photovoltaics companies
- Maximum power point tracker
- Photoelectrochemical cell
- Photovoltaic and renewable energy engineering in Australia
- Photovoltaic cell
- Solar cell research
- Solar energy
- Solar thermal energy
Notes
- ^ The city of Berkeley has come up with an innovative financing method to remove this limitation, by adding a tax assessment that is transferred with the home to pay for the solar panels. (See: "Berkeley FIRST Solar Financing – City of Berkeley, CA". cityofberkeley.info. Retrieved September 7, 2010.) 28 U.S. states have duplicated this solution.
- ^ Feed-in-tarrifs (See: "Solar PV as a Domestic Investment Opportunity: The Options". www.evoenergy.co.uk. Retrieved October 28, 2010.) allow homeowners to both generate both free electricity and earn a fee (tarrif) or credit for surplus power generated.
- ^ Utility rates have increased every year for the past 20 years[citation needed] and with the increasing pressure on carbon reduction the rate will increase more aggressively. (See: "EIA – Electricity Data, Analysis, Surveys". eia.doe.gov. Retrieved September 7, 2010.) These increases will (in the long run) easily offset the increased cost at installation but the timetable for payback is still considered long.[citation needed]
- ^ Many buildings with photovoltaic arrays are tied into the power grid; the grid absorbs excess electricity generated throughout the day, and provides electricity in the evening.
- ^ Insolation figures of 3–7 kilowatt·h/m² for the contiguous US are from the map colors which slightly contradict the table above which claims 900 to 2100 yearly insolation, that makes 2.46 to 5.7 daily. Also, second cite does not claim 3 or 7, third cite also makes no mention. There is also a need to clarify what kind of insolation is meant, presumably vertical.
References
- ^ a b c Mark Z. Jacobson (2009). Review of Solutions to Global Warming, Air Pollution, and Energy Security p. 4.
- ^ a b c German PV market
- ^ a b BP Solar to Expand Its Solar Cell Plants in Spain and India
- ^ a b Large-Scale, Cheap Solar Electricity
- ^ a b REN21. Renewables 2010 Global Status Report p. 19.
- ^ a b GE Invests, Delivers One of World's Largest Solar Power Plants
- ^ a b Building integrated photovoltaics
- ^ Richard M. Swanson. Photovoltaics Power Up, Science, Vol. 324, 15 May 2009, p. 891.
- ^ The Photovoltaic Effect – Introduction. Photovoltaics.sandia.gov (2001-02-01). Retrieved on 2010-12-12.
- ^ The photovoltaic effect. Scienzagiovane.unibo.it (2006-12-01). Retrieved on 2010-12-12.
- ^ Photovoltaic Effect. Mrsolar.com. Retrieved on 2010-12-12.
- ^ The photovoltaic effect. Encyclobeamia.solarbotics.net. Retrieved on 2010-12-12.
- ^ Boom and bust for Spain's heavily subsidized solar industry
- ^ In India’s Sea of Darkness: An Unsustainable Island of Decentralized Energy Production
- ^ Solar Expected to Maintain its Status as the World's Fastest-Growing Energy Technology
- ^ a b James Russell. Record Growth in Photovoltaic Capacity and Momentum Builds for Concentrating Solar Power Vital Signs, June 03, 2010.
- ^ MarketBuzz 2008: Annual World Solar Photovoltaic Industry Report
- ^ World PV Industry Report Summary March 16, 2009 retrieved 28 March 2009
- ^ World PV Industry Report Summary March 15, 2010 retrieved 26 September 2010
- ^ [1] March 15, 2011 retrieved 18 March 2011
- ^ a b c Germany To Raise Solar Target for 2010 & Adjust Tariffs | Renewable Energy News Article. Renewableenergyworld.com. Retrieved on 2010-12-12.
- ^ Global Solar Photovoltaic Market Analysis and Forecasts to 2020
- ^ Antonio Luque and Steven Hegedus (2003). Handbook of Photovoltaic Science and Engineering. John Wiley and Sons. ISBN 0471491969.
- ^ The PVWatts Solar Calculator
- ^ UtiliPoint International, Inc. 'Issue alert – What is a megawatt?
- ^ Total electric power consumption
- ^ Solar Generation V – 2008
- ^ Company Information Overview
- ^ The technology at a glance
- ^ Converting sunlight to electricity
- ^ "Thin-film's Share of Solar Panel Market to Double by 2013". renewableenergyworld.com. Retrieved July 7, 2010.
{{cite web}}: Text "Renewable Energy World" ignored (help) - ^ A Better Way to Make Solar Power
- ^ Solar Photovoltaic Panels
- ^ MMA Renewable Ventures Solar Energy Program
- ^ U.S. Retailers Save with Solar PV & Energy Efficiency
- ^ Solar Power Services: How PPAs are Changing the PV Value Chain
- ^ Berkeley FIRST. Retrieved October 14, 2010.
- ^ "SunPower TM 318 Solar Panel Data Sheet" (PDF). SunPower. February, 2010. Retrieved 30 March 2011.
{{cite web}}: Check date values in:|date=(help) - ^ UD-led team sets solar cell record, joins DuPont on $100 million project. Retrieved 8 October 2008.
- ^ Sharp Develops Solar Cell with World's Highest Conversion Efficiency of 35.8%
- ^ "Caltech Researchers Create Highly Absorbing, Flexible Solar Cells with Silicon Wire Arrays". California Institute of Technology. February 16, 2010. Retrieved 7 March 2010.
- ^ a b Denis Lenardic. Large-scale photovoltaic power plants ranking 1 - 50 PVresources.com, 2010.
- ^ http://blogs.worldbank.org/climatechange/will-china-and-us-be-partners-or-rivals-new-energy-economy
- ^ Building Integrated Photovoltaics, Wisconsin Public Service Corporation, accessed: 2007-03-23.
- ^ SolidWorks Plays Key Role in Cambridge Eco Race Effort. Retrieved 8 February 2009.
- ^ "Solar water pumping". builditsolar.com. Retrieved June 16, 2010.
- ^ Solar-Powered Parking Meters Installed
- ^ Security Products, December 2006, p42
- ^ Philadelphia's Solar-Powered Trash Compactors
- ^ Solar loans light up rural India
- ^ Off grid solutions for remote poor
- ^ Rural Cuba Basks in the Sun
- ^ Solar Roads attract funding
- ^ Effect of Panel Temperature on a Solar-Pv Ac Water Pumping System
- ^ a b Vaclav Smil – Energy at the Crossroads
- ^ Environmental Aspects of PV Power Systems
- ^ N. C. McDonald and J. M. Pearce, Producer Responsibility and Recycling Solar Photovoltaic Modules, Energy Policy 38, pp. 7041–7047(2010).
- ^ U.S. Climate Change Technology Program – Transmission and Distribution Technologies
- ^ World Record: 41.1% efficiency reached for multi-junction solar cells Fraunhofer ISE
- ^ solarcellsinfo.com
- ^ NREL Map of Flat Plate Collector at Latitude Tilt Yearly Average Solar Radiation See also NREL.gov
- ^ Solar Energy Technologies Program: Solar FAQs US Department of Energy. Retrieved on 24 August 2007,
- ^ Solar panel achieves high efficiency
- ^ Renewable Resource Data Center – PV Correction Factors
External energy
| Concepts |    | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Solar power |
| ||||||||||||||||
| Distribution and uses |
| ||||||||||||||||
| Applications |
| ||||||||||||||||
| See also | |||||||||||||||||
