title: Solar cell

text: In recent years, research has moved towards designing and manufacturing lightweight, flexible, and highly efficient solar cells. Terrestrial solar cell technology generally uses photovoltaic cells that are laminated with a layer of glass for strength and protection. Space applications for solar cells require that the cells and arrays are both highly efficient and extremely lightweight. Some newer technology implemented on satellites are multi-junction photovoltaic cells, which are composed of different PN junctions with varying bandgaps in order to utilize a wider spectrum of the sun's energy. Additionally, large satellites require the use of large solar arrays to produce electricity. These solar arrays need to be broken down to fit in the geometric constraints of the launch vehicle the satellite travels on before being injected into orbit. Historically, solar cells on satellites consisted of several small terrestrial panels folded together. These small panels would be unfolded into a large panel after the satellite is deployed in its orbit. Newer satellites aim to use flexible rollable solar arrays that are very lightweight and can be packed into a very small volume. The smaller size and weight of these flexible arrays drastically decreases the overall cost of launching a satellite due to the direct relationship between payload weight and launch cost of a launch vehicle.


title: Solar cell

text: In 2020, the US Naval Research Laboratory conducted its first test of solar power generation in a satellite, the Photovoltaic Radio-frequency Antenna Module (PRAM) experiment aboard the Boeing X-37.


title: Solar cell

text: Improvements were gradual over the 1960s. This was also the reason that costs remained high, because space users were willing to pay for the best possible cells, leaving no reason to invest in lower-cost, less-efficient solutions. The price was determined largely by the semiconductor industry; their move to integrated circuits in the 1960s led to the availability of larger boules at lower relative prices. As their price fell, the price of the resulting cells did as well. These effects lowered 1971 cell costs to some $100 per watt.


title: Solar cell

text: In late 1969 Elliot Berman joined Exxon's task force which was looking for projects 30 years in the future and in April 1973 he founded Solar Power Corporation (SPC), a wholly owned subsidiary of Exxon at that time. The group had concluded that electrical power would be much more expensive by 2000, and felt that this increase in price would make alternative energy sources more attractive. He conducted a market study and concluded that a price per watt of about $20/watt would create significant demand. The team eliminated the steps of polishing the wafers and coating them with an anti-reflective layer, relying on the rough-sawn wafer surface. The team also replaced the expensive materials and hand wiring used in space applications with a printed circuit board on the back, acrylic plastic on the front, and silicone glue between the two, "potting" the cells. Solar cells could be made using cast-off material from the electronics market. By 1973 they announced a product, and SPC convinced Tideland Signal to use its panels to power navigational buoys, initially for the U.S. Coast Guard.


title: Solar cell

text: Research into solar power for terrestrial applications became prominent with the U.S. National Science Foundation's Advanced Solar Energy Research and Development Division within the "Research Applied to National Needs" program, which ran from 1969 to 1977, and funded research on developing solar power for ground electrical power systems. A 1973 conference, the "Cherry Hill Conference", set forth the technology goals required to achieve this goal and outlined an ambitious project for achieving them, kicking off an applied research program that would be ongoing for several decades. The program was eventually taken over by the Energy Research and Development Administration (ERDA), which was later merged into the U.S. Department of Energy.


title: Solar cell

text: Following the 1973 oil crisis, oil companies used their higher profits to start (or buy) solar firms, and were for decades the largest producers. Exxon, ARCO, Shell, Amoco (later purchased by BP) and Mobil all had major solar divisions during the 1970s and 1980s. Technology companies also participated, including General Electric, Motorola, IBM, Tyco and RCA.


title: Solar cell

text: Adjusting for inflation, it cost $96 per watt for a solar module in the mid-1970s. Process improvements and a very large boost in production have brought that figure down more than 99%, to 30¢ per watt in 2018


title: Solar cell

text: Swanson's law is an observation similar to Moore's Law that states that solar cell prices fall 20% for every doubling of industry capacity. It was featured in an article in the British weekly newspaper The Economist in late 2012. Balance of system costs were then higher than those of the panels. Large commercial arrays could be built, as of 2018, at below $1.00 a watt, fully commissioned.


title: Solar cell

text: As the semiconductor industry moved to ever-larger boules, older equipment became inexpensive. Cell sizes grew as equipment became available on the surplus market; ARCO Solar's original panels used cells in diameter. Panels in the 1990s and early 2000s generally used 125 mm wafers; since 2008, almost all new panels use 156 mm cells. The widespread introduction of flat screen televisions in the late 1990s and early 2000s led to the wide availability of large, high-quality glass sheets to cover the panels.


title: Solar cell

text: During the 1990s, polysilicon ("poly") cells became increasingly popular. These cells offer less efficiency than their monosilicon ("mono") counterparts, but they are grown in large vats that reduce cost. By the mid-2000s, poly was dominant in the low-cost panel market, but more recently the mono returned to widespread use.


title: Solar cell

text: Manufacturers of wafer-based cells responded to high silicon prices in 2004–2008 with rapid reductions in silicon consumption. In 2008, according to Jef Poortmans, director of IMEC's organic and solar department, current cells use of silicon per watt of power generation, with wafer thicknesses in the neighborhood of 200 microns. Crystalline silicon panels dominate worldwide markets and are mostly manufactured in China and Taiwan. By late 2011, a drop in European demand dropped prices for crystalline solar modules to about $1.09 per watt down sharply from 2010. Prices continued to fall in 2012, reaching $0.62/watt by 4Q2012.


title: Solar cell

text: Solar PV is growing fastest in Asia, with China and Japan currently accounting for half of worldwide deployment. Global installed PV capacity reached at least 301 gigawatts in 2016, and grew to supply 1.3% of global power by 2016.


title: Solar cell

text: It was anticipated that electricity from PV will be competitive with wholesale electricity costs all across Europe and the energy payback time of crystalline silicon modules can be reduced to below 0.5 years by 2020.


title: Solar cell

text: Falling costs are considered one of the biggest factors in the rapid growth of renewable energy, with the cost of solar photovoltaic electricity falling by ~85% between 2010 (when solar and wind made up 1.7% of global electricity generation) and 2021 (where they made up 8.7%). In 2019 solar cells accounted for ~3 % of the world's electricity generation.


title: Solar cell

text: Solar-specific feed-in tariffs vary by country and within countries. Such tariffs encourage the development of solar power projects. Widespread grid parity, the point at which photovoltaic electricity is equal to or cheaper than grid power without subsidies, likely requires advances on all three fronts. Proponents of solar hope to achieve grid parity first in areas with abundant sun and high electricity costs such as in California and Japan. In 2007 BP claimed grid parity for Hawaii and other islands that otherwise use diesel fuel to produce electricity. George W. Bush set 2015 as the date for grid parity in the US. The Photovoltaic Association reported in 2012 that Australia had reached grid parity (ignoring feed in tariffs).


title: Solar cell

text: The price of solar panels fell steadily for 40 years, interrupted in 2004 when high subsidies in Germany drastically increased demand there and greatly increased the price of purified silicon (which is used in computer chips as well as solar panels). The recession of 2008 and the onset of Chinese manufacturing caused prices to resume their decline. In the four years after January 2008 prices for solar modules in Germany dropped from €3 to €1 per peak watt. During that same time production capacity surged with an annual growth of more than 50%. China increased market share from 8% in 2008 to over 55% in the last quarter of 2010. In December 2012 the price of Chinese solar panels had dropped to $0.60/Wp (crystalline modules). (The abbreviation Wp stands for watt peak capacity, or the maximum capacity under optimal conditions.)


title: Solar cell

text: As of the end of 2016, it was reported that spot prices for assembled solar "panels" (not cells) had fallen to a record-low of US$0.36/Wp. The second largest supplier, Canadian Solar Inc., had reported costs of US$0.37/Wp in the third quarter of 2016, having dropped $0.02 from the previous quarter, and hence was probably still at least breaking even. Many producers expected costs would drop to the vicinity of $0.30 by the end of 2017. It was also reported that new solar installations were cheaper than coal-based thermal power plants in some regions of the world, and this was expected to be the case in most of the world within a decade.


title: Solar cell

text: The most commonly known solar cell is configured as a large-area p–n junction made from silicon. Other possible solar cell types are organic solar cells, dye sensitized solar cells, perovskite solar cells, quantum dot solar cells etc. The illuminated side of a solar cell generally has a transparent conducting film for allowing light to enter into the active material and to collect the generated charge carriers. Typically, films with high transmittance and high electrical conductance such as indium tin oxide, conducting polymers or conducting nanowire networks are used for the purpose.


title: Solar cell

text: Solar cell efficiency may be broken down into reflectance efficiency, thermodynamic efficiency, charge carrier separation efficiency and conductive efficiency. The overall efficiency is the product of these individual metrics.


title: Solar cell

text: The power conversion efficiency of a solar cell is a parameter which is defined by the fraction of incident power converted into electricity.


title: Solar cell

text: A solar cell has a voltage dependent efficiency curve, temperature coefficients, and allowable shadow angles.


title: Solar cell

text: Due to the difficulty in measuring these parameters directly, other parameters are substituted: thermodynamic efficiency, quantum efficiency, integrated quantum efficiency, V ratio, and fill factor. Reflectance losses are a portion of quantum efficiency under "external quantum efficiency". Recombination losses make up another portion of quantum efficiency, V ratio, and fill factor. Resistive losses are predominantly categorized under fill factor, but also make up minor portions of quantum efficiency, V ratio.


title: Solar cell

text: The fill factor is the ratio of the actual maximum obtainable power to the product of the open-circuit voltage and short-circuit current. This is a key parameter in evaluating performance. In 2009, typical commercial solar cells had a fill factor > 0.70. Grade B cells were usually between 0.4 and 0.7. Cells with a high fill factor have a low equivalent series resistance and a high equivalent shunt resistance, so less of the current produced by the cell is dissipated in internal losses.


title: Solar cell

text: Single p–n junction crystalline silicon devices are now approaching the theoretical limiting power efficiency of 33.16%, noted as the Shockley–Queisser limit in 1961. In the extreme, with an infinite number of layers, the corresponding limit is 86% using concentrated sunlight.


title: Solar cell

text: In 2014, three companies broke the record of 25.6% for a silicon solar cell. Panasonic's was the most efficient. The company moved the front contacts to the rear of the panel, eliminating shaded areas. In addition they applied thin silicon films to the (high quality silicon) wafer's front and back to eliminate defects at or near the wafer surface.


title: Solar cell

text: In 2015, a 4-junction GaInP/GaAs//GaInAsP/GaInAs solar cell achieved a new laboratory record efficiency of 46.1% (concentration ratio of sunlight = 312) in a French-German collaboration between the Fraunhofer Institute for Solar Energy Systems (Fraunhofer ISE), CEA-LETI and SOITEC.


title: Solar cell

text: In September 2015, Fraunhofer ISE announced the achievement of an efficiency above 20% for epitaxial wafer cells. The work on optimizing the atmospheric-pressure chemical vapor deposition (APCVD) in-line production chain was done in collaboration with NexWafe GmbH, a company spun off from Fraunhofer ISE to commercialize production.


title: Solar cell

text: In 2016, researchers at Fraunhofer ISE announced a GaInP/GaAs/Si triple-junction solar cell with two terminals reaching 30.2% efficiency without concentration.


title: Solar cell

text: In 2017, a team of researchers at National Renewable Energy Laboratory (NREL), EPFL and CSEM (Switzerland) reported record one-sun efficiencies of 32.8% for dual-junction GaInP/GaAs solar cell devices. In addition, the dual-junction device was mechanically stacked with a Si solar cell, to achieve a record one-sun efficiency of 35.9% for triple-junction solar cells.


title: Solar cell

text: Solar cells are typically named after the semiconducting material they are made of. These materials must have certain characteristics in order to absorb sunlight. Some cells are designed to handle sunlight that reaches the Earth's surface, while others are optimized for use in space. Solar cells can be made of a single layer of light-absorbing material (single-junction) or use multiple physical configurations (multi-junctions) to take advantage of various absorption and charge separation mechanisms.


title: Solar cell

text: Solar cells can be classified into first, second and third generation cells. The first generation cells—also called conventional, traditional or wafer-based cells—are made of crystalline silicon, the commercially predominant PV technology, that includes materials such as polysilicon and monocrystalline silicon. Second generation cells are thin film solar cells, that include amorphous silicon, CdTe and CIGS cells and are commercially significant in utility-scale photovoltaic power stations, building integrated photovoltaics or in small stand-alone power system. The third generation of solar cells includes a number of thin-film technologies often described as emerging photovoltaics—most of them have not yet been commercially applied and are still in the research or development phase. Many use organic materials, often organometallic compounds as well as inorganic substances. Despite the fact that their efficiencies had been low and the stability of the absorber material was often too short for commercial applications, there is research into these technologies as they promise to achieve the goal of producing low-cost, high-efficiency solar cells.


title: Solar cell

text: By far, the most prevalent bulk material for solar cells is crystalline silicon (c-Si), also known as "solar grade silicon". Bulk silicon is separated into multiple categories according to crystallinity and crystal size in the resulting ingot, ribbon or wafer. These cells are entirely based around the concept of a p–n junction. Solar cells made of c-Si are made from wafers between 160 and 240 micrometers thick.


title: Solar cell

text: Monocrystalline silicon (mono-Si) solar cells feature a single-crystal composition that enables electrons to move more freely than in a multi-crystal configuration. Consequently, monocrystalline solar panels deliver a higher efficiency than their multicrystalline counterparts. The corners of the cells look clipped, like an octagon, because the wafer material is cut from cylindrical ingots, that are typically grown by the Czochralski process. Solar panels using mono-Si cells display a distinctive pattern of small white diamonds.


title: Solar cell

text: Epitaxial wafers of crystalline silicon can be grown on a monocrystalline silicon "seed" wafer by chemical vapor deposition (CVD), and then detached as self-supporting wafers of some standard thickness (e.g., 250 µm) that can be manipulated by hand, and directly substituted for wafer cells cut from monocrystalline silicon ingots. Solar cells made with this "kerfless" technique can have efficiencies approaching those of wafer-cut cells, but at appreciably lower cost if the CVD can be done at atmospheric pressure in a high-throughput inline process. The surface of epitaxial wafers may be textured to enhance light absorption.


title: Solar cell

text: In June 2015, it was reported that heterojunction solar cells grown epitaxially on n-type monocrystalline silicon wafers had reached an efficiency of 22.5% over a total cell area of 243.4 cmformula_1.


title: Solar cell

text: Polycrystalline silicon, or multicrystalline silicon (multi-Si) cells are made from cast square ingots—large blocks of molten silicon carefully cooled and solidified. They consist of small crystals giving the material its typical metal flake effect. Polysilicon cells are the most common type used in photovoltaics and are less expensive, but also less efficient, than those made from monocrystalline silicon.


title: Solar cell

text: Ribbon silicon is a type of polycrystalline silicon—it is formed by drawing flat thin films from molten silicon and results in a polycrystalline structure. These cells are cheaper to make than multi-Si, due to a great reduction in silicon waste, as this approach does not require sawing from ingots. However, they are also less efficient.


title: Solar cell

text: This form was developed in the 2000s and introduced commercially around 2009. Also called cast-mono, this design uses polycrystalline casting chambers with small "seeds" of mono material. The result is a bulk mono-like material that is polycrystalline around the outsides. When sliced for processing, the inner sections are high-efficiency mono-like cells (but square instead of "clipped"), while the outer edges are sold as conventional poly. This production method results in mono-like cells at poly-like prices.


title: Solar cell

text: Thin-film technologies reduce the amount of active material in a cell. Most designs sandwich active material between two panes of glass. Since silicon solar panels only use one pane of glass, thin film panels are approximately twice as heavy as crystalline silicon panels, although they have a smaller ecological impact (determined from life cycle analysis).


title: Solar cell

text: Cadmium telluride is the only thin film material so far to rival crystalline silicon in cost/watt. However cadmium is highly toxic and tellurium (anion: "telluride") supplies are limited. The cadmium present in the cells would be toxic if released. However, release is impossible during normal operation of the cells and is unlikely during fires in residential roofs. A square meter of CdTe contains approximately the same amount of Cd as a single C cell nickel-cadmium battery, in a more stable and less soluble form.


title: Solar cell

text: Copper indium gallium selenide (CIGS) is a direct band gap material. It has the highest efficiency (~20%) among all commercially significant thin film materials (see CIGS solar cell). Traditional methods of fabrication involve vacuum processes including co-evaporation and sputtering. Recent developments at IBM and Nanosolar attempt to lower the cost by using non-vacuum solution processes.


title: Solar cell

text: Silicon thin-film cells are mainly deposited by chemical vapor deposition (typically plasma-enhanced, PE-CVD) from silane gas and hydrogen gas. Depending on the deposition parameters, this can yield amorphous silicon (a-Si or a-Si:H), protocrystalline silicon or nanocrystalline silicon (nc-Si or nc-Si:H), also called microcrystalline silicon.


title: Solar cell

text: Amorphous silicon is the most well-developed thin film technology to-date. An amorphous silicon (a-Si) solar cell is made of non-crystalline or microcrystalline silicon. Amorphous silicon has a higher bandgap (1.7 eV) than crystalline silicon (c-Si) (1.1 eV), which means it absorbs the visible part of the solar spectrum more strongly than the higher power density infrared portion of the spectrum. The production of a-Si thin film solar cells uses glass as a substrate and deposits a very thin layer of silicon by plasma-enhanced chemical vapor deposition (PECVD).


title: Solar cell

text: Protocrystalline silicon with a low volume fraction of nanocrystalline silicon is optimal for high open-circuit voltage. Nc-Si has about the same bandgap as c-Si and nc-Si and a-Si can advantageously be combined in thin layers, creating a layered cell called a tandem cell. The top cell in a-Si absorbs the visible light and leaves the infrared part of the spectrum for the bottom cell in nc-Si.


title: Solar cell

text: The semiconductor material gallium arsenide (GaAs) is also used for single-crystalline thin film solar cells. Although GaAs cells are very expensive, they hold the world's record in efficiency for a single-junction solar cell at 28.8%. GaAs is more commonly used in multijunction photovoltaic cells for concentrated photovoltaics (CPV, HCPV) and for solar panels on spacecraft, as the industry favours efficiency over cost for space-based solar power. Based on the previous literature and some theoretical analysis, there are several reasons why GaAs has such high power conversion efficiency. First, GaAs bandgap is 1.43ev which is almost ideal for solar cells. Second, because Gallium is a by-product of the smelting of other metals, GaAs cells are relatively insensitive to heat and it can keep high efficiency when temperature is quite high. Third, GaAs has the wide range of design options. Using GaAs as active layer in solar cell, engineers can have multiple choices of other layers which can better generate electrons and holes in GaAs.


title: Solar cell

text: Multi-junction cells consist of multiple thin films, each essentially a solar cell grown on top of another, typically using metalorganic vapour phase epitaxy. Each layer has a different band gap energy to allow it to absorb electromagnetic radiation over a different portion of the spectrum. Multi-junction cells were originally developed for special applications such as satellites and space exploration, but are now used increasingly in terrestrial concentrator photovoltaics (CPV), an emerging technology that uses lenses and curved mirrors to concentrate sunlight onto small, highly efficient multi-junction solar cells. By concentrating sunlight up to a thousand times, "High concentration photovoltaics (HCPV)" has the potential to outcompete conventional solar PV in the future.


title: Solar cell

text: Tandem solar cells based on monolithic, series connected, gallium indium phosphide (GaInP), gallium arsenide (GaAs), and germanium (Ge) p–n junctions, are increasing sales, despite cost pressures. Between December 2006 and December 2007, the cost of 4N gallium metal rose from about $350 per kg to $680 per kg. Additionally, germanium metal prices have risen substantially to $1000–1200 per kg this year. Those materials include gallium (4N, 6N and 7N Ga), arsenic (4N, 6N and 7N) and germanium, pyrolitic boron nitride (pBN) crucibles for growing crystals, and boron oxide, these products are critical to the entire substrate manufacturing industry.


title: Solar cell

text: A triple-junction cell, for example, may consist of the semiconductors: GaAs, Ge, and . Triple-junction GaAs solar cells were used as the power source of the Dutch four-time World Solar Challenge winners Nuna in 2003, 2005 and 2007 and by the Dutch solar cars Solutra (2005), Twente One (2007) and 21Revolution (2009). GaAs based multi-junction devices are the most efficient solar cells to date. On 15 October 2012, triple junction metamorphic cells reached a record high of 44%.


title: Solar cell

text: In 2016, a new approach was described for producing hybrid photovoltaic wafers combining the high efficiency of III-V multi-junction solar cells with the economies and wealth of experience associated with silicon. The technical complications involved in growing the III-V material on silicon at the required high temperatures, a subject of study for some 30 years, are avoided by epitaxial growth of silicon on GaAs at low temperature by plasma-enhanced chemical vapor deposition (PECVD).


title: Solar cell

text: Si single-junction solar cells have been widely studied for decades and are reaching their practical efficiency of ~26% under 1-sun conditions. Increasing this efficiency may require adding more cells with bandgap energy larger than 1.1 eV to the Si cell, allowing to convert short-wavelength photons for generation of additional voltage. A dual-junction solar cell with a band gap of 1.6–1.8 eV as a top cell can reduce thermalization loss, produce a high external radiative efficiency and achieve theoretical efficiencies over 45%. A tandem cell can be fabricated by growing the GaInP and Si cells. Growing them separately can overcome the 4% lattice constant mismatch between Si and the most common III–V layers that prevent direct integration into one cell. The two cells therefore are separated by a transparent glass slide so the lattice mismatch does not cause strain to the system. This creates a cell with four electrical contacts and two junctions that demonstrated an efficiency of 18.1%. With a fill factor (FF) of 76.2%, the Si bottom cell reaches an efficiency of 11.7% (± 0.4) in the tandem device, resulting in a cumulative tandem cell efficiency of 29.8%. This efficiency exceeds the theoretical limit of 29.4% and the record experimental efficiency value of a Si 1-sun solar cell, and is also higher than the record-efficiency 1-sun GaAs device. However, using a GaAs substrate is expensive and not practical. Hence researchers try to make a cell with two electrical contact points and one junction, which does not need a GaAs substrate. This means there will be direct integration of GaInP and Si.


title: Solar cell

text: Perovskite solar cells are solar cells that include a perovskite-structured material as the active layer. Most commonly, this is a solution-processed hybrid organic-inorganic tin or lead halide based material. Efficiencies have increased from below 5% at their first usage in 2009 to 25.5% in 2020, making them a very rapidly advancing technology and a hot topic in the solar cell field. Perovskite solar cells are also forecast to be extremely cheap to scale up, making them a very attractive option for commercialisation. So far most types of perovskite solar cells have not reached sufficient operational stability to be commercialised, although many research groups are investigating ways to solve this. Energy and environmental sustainability of perovskite solar cells and tandem perovskite are shown to be dependent on the structures. The inclusion of the toxic element lead in the most efficient perovskite solar cells is a potential problem for commercialisation.


title: Solar cell

text: With a transparent rear side, bifacial solar cells can absorb light from both the front and rear sides. Hence, they can produce more electricity than conventional monofacial solar cells. The first patent of bifacial solar cells was filed by Japanese researcher Hiroshi Mori, in 1966. Later, it is said that Russia was the first to deploy bifacial solar cells in their space program in the 1970s. In 1976, the Institute for Solar Energy of the Technical University of Madrid, began a research program for the development of bifacial solar cells led by Prof. Antonio Luque. Based on 1977 US and Spanish patents by Luque, a practical bifacial cell was proposed with a front face as anode and a rear face as cathode; in previously reported proposals and attempts both faces were anodic and interconnection between cells was complicated and expensive. In 1980, Andrés Cuevas, a PhD student in Luque's team, demonstrated experimentally a 50% increase in output power of bifacial solar cells, relative to identically oriented and tilted monofacial ones, when a white background was provided. In 1981 the company Isofoton was founded in Málaga to produce the developed bifacial cells, thus becoming the first industrialization of this PV cell technology. With an initial production capacity of 300 kW/yr. of bifacial solar cells, early landmarks of Isofoton's production were the 20kWp power plant in San Agustín de Guadalix, built in 1986 for Iberdrola, and an off grid installation by 1988 also of 20kWp in the village of Noto Gouye Diama (Senegal) funded by the Spanish international aid and cooperation programs.


title: Solar cell

text: Due to the reduced manufacturing cost, companies have again started to produce commercial bifacial modules since 2010. By 2017, there were at least eight certified PV manufacturers providing bifacial modules in North America. It has been predicted by the International Technology Roadmap for Photovoltaics (ITRPV) that the global market share of bifacial technology will expand from less than 5% in 2016 to 30% in 2027.


title: Solar cell

text: Due to the significant interest in the bifacial technology, a recent study has investigated the performance and optimization of bifacial solar modules worldwide. The results indicate that, across the globe, ground-mounted bifacial modules can only offer ~10% gain in annual electricity yields compared to the monofacial counterparts for a ground albedo coefficient of 25% (typical for concrete and vegetation groundcovers). However, the gain can be increased to ~30% by elevating the module 1 m above the ground and enhancing the ground albedo coefficient to 50%. Sun "et al." also derived a set of empirical equations that can optimize bifacial solar modules analytically. In addition, there is evidence that bifacial panels work better than traditional panels in snowy environments - as bifacials on dual-axis trackers made 14% more electricity in a year than their monofacial counterparts and 40% during the peak winter months.


title: Solar cell

text: An online simulation tool is available to model the performance of bifacial modules in any arbitrary location across the entire world. It can also optimize bifacial modules as a function of tilt angle, azimuth angle, and elevation above the ground.


title: Solar cell

text: Intermediate band photovoltaics in solar cell research provides methods for exceeding the Shockley–Queisser limit on the efficiency of a cell. It introduces an intermediate band (IB) energy level in between the valence and conduction bands. Theoretically, introducing an IB allows two photons with energy less than the bandgap to excite an electron from the valence band to the conduction band. This increases the induced photocurrent and thereby efficiency.


title: Solar cell

text: Luque and Marti first derived a theoretical limit for an IB device with one midgap energy level using detailed balance. They assumed no carriers were collected at the IB and that the device was under full concentration. They found the maximum efficiency to be 63.2%, for a bandgap of 1.95eV with the IB 0.71eV from either the valence or conduction band.


title: Solar cell

text: In 2014, researchers at California NanoSystems Institute discovered using kesterite and perovskite improved electric power conversion efficiency for solar cells.


title: Solar cell

text: Photon upconversion is the process of using two low-energy ("e.g.", infrared) photons to produce one higher energy photon; downconversion is the process of using one high energy photon ("e.g.", ultraviolet) to produce two lower energy photons. Either of these techniques could be used to produce higher efficiency solar cells by allowing solar photons to be more efficiently used. The difficulty, however, is that the conversion efficiency of existing phosphors exhibiting up- or down-conversion is low, and is typically narrow band.


title: Solar cell

text: One upconversion technique is to incorporate lanthanide-doped materials (, , or a combination), taking advantage of their luminescence to convert infrared radiation to visible light. Upconversion process occurs when two infrared photons are absorbed by rare-earth ions to generate a (high-energy) absorbable photon. As example, the energy transfer upconversion process (ETU), consists in successive transfer processes between excited ions in the near infrared. The upconverter material could be placed below the solar cell to absorb the infrared light that passes through the silicon. Useful ions are most commonly found in the trivalent state. ions have been the most used. ions absorb solar radiation around 1.54 µm. Two ions that have absorbed this radiation can interact with each other through an upconversion process. The excited ion emits light above the Si bandgap that is absorbed by the solar cell and creates an additional electron–hole pair that can generate current. However, the increased efficiency was small. In addition, fluoroindate glasses have low phonon energy and have been proposed as suitable matrix doped with ions.


title: Solar cell

text: Dye-sensitized solar cells (DSSCs) are made of low-cost materials and do not need elaborate manufacturing equipment, so they can be made in a DIY fashion. In bulk it should be significantly less expensive than older solid-state cell designs. DSSC's can be engineered into flexible sheets and although its conversion efficiency is less than the best thin film cells, its price/performance ratio may be high enough to allow them to compete with fossil fuel electrical generation.


title: Solar cell

text: Typically a ruthenium metalorganic dye (Ru-centered) is used as a monolayer of light-absorbing material, which is adsorbed onto a thin film of titanium dioxide. The dye-sensitized solar cell depends on this mesoporous layer of nanoparticulate titanium dioxide (TiO) to greatly amplify the surface area (200–300 m/g , as compared to approximately 10 m/g of flat single crystal) which allows for a greater number of dyes per solar cell area (which in term in increases the current). The photogenerated electrons from the light absorbing dye are passed on to the n-type and the holes are absorbed by an electrolyte on the other side of the dye. The circuit is completed by a redox couple in the electrolyte, which can be liquid or solid. This type of cell allows more flexible use of materials and is typically manufactured by screen printing or ultrasonic nozzles, with the potential for lower processing costs than those used for bulk solar cells. However, the dyes in these cells also suffer from degradation under heat and UV light and the cell casing is difficult to seal due to the solvents used in assembly. Due to this reason, researchers have developed solid-state dye-sensitized solar cells that use a solid electrolyte to avoid leakage. The first commercial shipment of DSSC solar modules occurred in July 2009 from G24i Innovations.


title: Solar cell

text: Quantum dot solar cells (QDSCs) are based on the Gratzel cell, or dye-sensitized solar cell architecture, but employ low band gap semiconductor nanoparticles, fabricated with crystallite sizes small enough to form quantum dots (such as CdS, CdSe, , PbS, etc.), instead of organic or organometallic dyes as light absorbers. Due to the toxicity associated with Cd and Pb based compounds there are also a series of "green" QD sensitizing materials in development (such as CuInS CuInSe and CuInSeS). QD's size quantization allows for the band gap to be tuned by simply changing particle size. They also have high extinction coefficients and have shown the possibility of multiple exciton generation.


title: Solar cell

text: In a QDSC, a mesoporous layer of titanium dioxide nanoparticles forms the backbone of the cell, much like in a DSSC. This layer can then be made photoactive by coating with semiconductor quantum dots using chemical bath deposition, electrophoretic deposition or successive ionic layer adsorption and reaction. The electrical circuit is then completed through the use of a liquid or solid redox couple. The efficiency of QDSCs has increased to over 5% shown for both liquid-junction and solid state cells, with a reported peak efficiency of 11.91%. In an effort to decrease production costs, the Prashant Kamat research group demonstrated a solar paint made with and CdSe that can be applied using a one-step method to any conductive surface with efficiencies over 1%. However, the absorption of quantum dots (QDs) in QDSCs is weak at room temperature. The plasmonic nanoparticles can be utilized to address the weak absorption of QDs (e.g., nanostars). Adding an external infrared pumping source to excite intraband and interband transition of QDs is another solution.


title: Solar cell

text: Organic solar cells and polymer solar cells are built from thin films (typically 100 nm) of organic semiconductors including polymers, such as polyphenylene vinylene and small-molecule compounds like copper phthalocyanine (a blue or green organic pigment) and carbon fullerenes and fullerene derivatives such as PCBM.


title: Solar cell

text: They can be processed from liquid solution, offering the possibility of a simple roll-to-roll printing process, potentially leading to inexpensive, large-scale production. In addition, these cells could be beneficial for some applications where mechanical flexibility and disposability are important. Current cell efficiencies are, however, very low, and practical devices are essentially non-existent.


title: Solar cell

text: Energy conversion efficiencies achieved to date using conductive polymers are very low compared to inorganic materials. However, Konarka Power Plastic reached efficiency of 8.3% and organic tandem cells in 2012 reached 11.1%.


title: Solar cell

text: The active region of an organic device consists of two materials, one electron donor and one electron acceptor. When a photon is converted into an electron hole pair, typically in the donor material, the charges tend to remain bound in the form of an exciton, separating when the exciton diffuses to the donor-acceptor interface, unlike most other solar cell types. The short exciton diffusion lengths of most polymer systems tend to limit the efficiency of such devices. Nanostructured interfaces, sometimes in the form of bulk heterojunctions, can improve performance.


title: Solar cell

text: In 2011, MIT and Michigan State researchers developed solar cells with a power efficiency close to 2% with a transparency to the human eye greater than 65%, achieved by selectively absorbing the ultraviolet and near-infrared parts of the spectrum with small-molecule compounds. Researchers at UCLA more recently developed an analogous polymer solar cell, following the same approach, that is 70% transparent and has a 4% power conversion efficiency. These lightweight, flexible cells can be produced in bulk at a low cost and could be used to create power generating windows.


title: Solar cell

text: In 2013, researchers announced polymer cells with some 3% efficiency. They used block copolymers, self-assembling organic materials that arrange themselves into distinct layers. The research focused on P3HT-b-PFTBT that separates into bands some 16 nanometers wide.


title: Solar cell

text: Adaptive cells change their absorption/reflection characteristics depending on environmental conditions. An adaptive material responds to the intensity and angle of incident light. At the part of the cell where the light is most intense, the cell surface changes from reflective to adaptive, allowing the light to penetrate the cell. The other parts of the cell remain reflective increasing the retention of the absorbed light within the cell.


title: Solar cell

text: In 2014, a system was developed that combined an adaptive surface with a glass substrate that redirect the absorbed to a light absorber on the edges of the sheet. The system also includes an array of fixed lenses/mirrors to concentrate light onto the adaptive surface. As the day continues, the concentrated light moves along the surface of the cell. That surface switches from reflective to adaptive when the light is most concentrated and back to reflective after the light moves along.


title: Solar cell

text: For the past years, researchers have been trying to reduce the price of solar cells while maximizing efficiency. Thin-film solar cell is a cost-effective second generation solar cell with much reduced thickness at the expense of light absorption efficiency. Efforts to maximize light absorption efficiency with reduced thickness have been made. Surface texturing is one of techniques used to reduce optical losses to maximize light absorbed. Currently, surface texturing techniques on silicon photovoltaics are drawing much attention. Surface texturing could be done in multiple ways. Etching single crystalline silicon substrate can produce randomly distributed square based pyramids on the surface using anisotropic etchants. Recent studies show that c-Si wafers could be etched down to form nano-scale inverted pyramids. Multicrystalline silicon solar cells, due to poorer crystallographic quality, are less effective than single crystal solar cells, but mc-Si solar cells are still being used widely due to less manufacturing difficulties. It is reported that multicrystalline solar cells can be surface-textured to yield solar energy conversion efficiency comparable to that of monocrystalline silicon cells, through isotropic etching or photolithography techniques. Incident light rays onto a textured surface do not reflect back out to the air as opposed to rays onto a flat surface. Rather some light rays are bounced back onto the other surface again due to the geometry of the surface. This process significantly improves light to electricity conversion efficiency, due to increased light absorption. This texture effect as well as the interaction with other interfaces in the PV module is a challenging optical simulation task. A particularly efficient method for modeling and optimization is the OPTOS formalism. In 2012, researchers at MIT reported that c-Si films textured with nanoscale inverted pyramids could achieve light absorption comparable to 30 times thicker planar c-Si. In combination with anti-reflective coating, surface texturing technique can effectively trap light rays within a thin film silicon solar cell. Consequently, required thickness for solar cells decreases with the increased absorption of light rays.


title: Solar cell

text: Solar cells are commonly encapsulated in a transparent polymeric resin to protect the delicate solar cell regions for coming into contact with moisture, dirt, ice, and other conditions expected either during operation or when used outdoors. The encapsulants are commonly made from polyvinyl acetate or glass. Most encapsulants are uniform in structure and composition, which increases light collection owing to light trapping from total internal reflection of light within the resin. Research has been conducted into structuring the encapsulant to provide further collection of light. Such encapsulants have included roughened glass surfaces, diffractive elements, prism arrays, air prisms, v-grooves, diffuse elements, as well as multi-directional waveguide arrays. Prism arrays show an overall 5% increase in the total solar energy conversion. Arrays of vertically aligned broadband waveguides provide a 10% increase at normal incidence, as well as wide-angle collection enhancement of up to 4%, with optimized structures yielding up to a 20% increase in short circuit current. Active coatings that convert infrared light into visible light have shown a 30% increase. Nanoparticle coatings inducing plasmonic light scattering increase wide-angle conversion efficiency up to 3%. Optical structures have also been created in encapsulation materials to effectively "cloak" the metallic front contacts.


title: Solar cell

text: Novel self-cleaning mechanisms for solar panels are being developed. For instance, in 2019 via wet-chemically etched nanowires and a hydrophobic coating on the surface water droplets could remove 98% of dust particles, which may be especially relevant for applications in the desert.


title: Solar cell

text: Solar cells share some of the same processing and manufacturing techniques as other semiconductor devices. However, the strict requirements for cleanliness and quality control of semiconductor fabrication are more relaxed for solar cells, lowering costs.


title: Solar cell

text: Polycrystalline silicon wafers are made by wire-sawing block-cast silicon ingots into 180 to 350 micrometer wafers. The wafers are usually lightly p-type-doped. A surface diffusion of n-type dopants is performed on the front side of the wafer. This forms a p–n junction a few hundred nanometers below the surface.


title: Solar cell

text: Anti-reflection coatings are then typically applied to increase the amount of light coupled into the solar cell. Silicon nitride has gradually replaced titanium dioxide as the preferred material, because of its excellent surface passivation qualities. It prevents carrier recombination at the cell surface. A layer several hundred nanometers thick is applied using plasma-enhanced chemical vapor deposition. Some solar cells have textured front surfaces that, like anti-reflection coatings, increase the amount of light reaching the wafer. Such surfaces were first applied to single-crystal silicon, followed by multicrystalline silicon somewhat later.


title: Solar cell

text: A full area metal contact is made on the back surface, and a grid-like metal contact made up of fine "fingers" and larger "bus bars" are screen-printed onto the front surface using a silver paste. This is an evolution of the so-called "wet" process for applying electrodes, first described in a US patent filed in 1981 by Bayer AG. The rear contact is formed by screen-printing a metal paste, typically aluminium. Usually this contact covers the entire rear, though some designs employ a grid pattern. The paste is then fired at several hundred degrees Celsius to form metal electrodes in ohmic contact with the silicon. Some companies use an additional electroplating step to increase efficiency. After the metal contacts are made, the solar cells are interconnected by flat wires or metal ribbons, and assembled into modules or "solar panels". Solar panels have a sheet of tempered glass on the front, and a polymer encapsulation on the back.


title: Solar cell

text: Different types of manufacturing and recycling partly determine how effective it is in decreasing emissions and having a positive environmental effect. Such differences and effectiveness could be quantified for production of the most optimal types of products for different purposes in different regions across time.


title: Solar cell

text: National Renewable Energy Laboratory tests and validates solar technologies. Three reliable groups certify solar equipment: UL and IEEE (both U.S. standards) and IEC.


title: Solar cell

text: Solar cells are manufactured in volume in Japan, Germany, China, Taiwan, Malaysia and the United States, whereas Europe, China, the U.S., and Japan have dominated (94% or more as of 2013) in installed systems. Other nations are acquiring significant solar cell production capacity.


title: Solar cell

text: Global PV cell/module production increased by 10% in 2012 despite a 9% decline in solar energy investments according to the annual "PV Status Report" released by the European Commission's Joint Research Centre. Between 2009 and 2013 cell production has quadrupled.


title: Solar cell

text: Since 2013 China has been the world's leading installer of solar photovoltaics (PV). As of September 2018, sixty percent of the world's solar photovoltaic modules were made in China. As of May 2018, the largest photovoltaic plant in the world is located in the Tengger desert in China. In 2018, China added more photovoltaic installed capacity (in GW) than the next 9 countries combined. As of 2022, China’s share in the manufacturing of solar panels exceeded 80% across all manufacturing stages.


title: Solar cell

text: In 2014, Malaysia was the world's third largest manufacturer of photovoltaics equipment, behind China and the European Union.


title: Solar cell

text: Solar energy production in the U.S. has doubled from 2013 to 2019. This was driven first by the falling price of quality silicon, and later simply by the globally plunging cost of photovoltaic modules. In 2018, the U.S. added 10.8GW of installed solar photovoltaic energy, an increase of 21%.


title: Solar cell

text: Like many other energy generation technologies, the manufacture of solar cells, especially its rapid expansion, has many environmental and supply-chain implications. Global mining may adapt and potentially expand for sourcing the needed minerals which vary per type of solar cell. Recycling solar panels could be a source for materials that would otherwise need to be mined.


title: Solar cell

text: Solar cells degrade over time and lose their efficiency. Solar cells in extreme climates, such as desert or polar, are more prone to degradation due to exposure to harsh UV light and snow loads respectively. Usually, solar panels are given a lifespan of 25–30 years before they get decommissioned.


title: Solar cell

text: The International Renewable Energy Agency estimated that the amount of solar panel electronic waste generated in 2016 was 43,500–250,000 metric tons. This number is estimated to increase substantially by 2030, reaching an estimated waste volume of 60–78 million metric tons in 2050.


title: Solar cell

text: Solar panels are recycled through different methods. The recycling process include a three step process, module recycling, cell recycling and waste handling, to break down Si modules and recover various materials. The recovered metals and Si are re-usable to the solar industry and generate $11–12.10/module in revenue at today's prices for Ag and solar-grade Si.


title: Solar cell

text: Some solar modules (For example: First Solar CdTe solar module) contains toxic materials like lead and cadmium which, when broken, could possible leach into the soil and contaminate the environment. The First Solar panel recycling plant opened in Rousset, France in 2018. It was set to recycle 1300 tonnes of solar panel waste a year, and can increase its capacity to 4000 tonnes.


title: Solar cell

text: In 2020, the first global assessment into promising approaches of solar photovoltaic modules recycling was published. Scientists recommended "research and development to reduce recycling costs and environmental impacts compared to disposal while maximizing material recovery" as well as facilitation and use of techno–economic analyses. Furthermore, they found the recovery of high-value silicon to be more advantageous than recovery of intact silicon wafers, with the former still requiring design of purification processes for recovered silicon. If recycling is driven only by market-based prices, rather than also environmental regulations, the economic incentives for recycling remain uncertain and as of 2021 the environmental impact of different types of developed recycling techniques still need to be quantified.


title: Al-Masjid an-Nabawi

text: Al-Masjid an-Nabawi (), known in English as the Prophet's Mosque, is a mosque built by the Islamic prophet Muhammad in the city of Medina in the Al Madinah Province of Saudi Arabia. It was the second mosque built by Muhammad in Medina, after Quba Mosque, and is the second largest mosque and second holiest site in Islam, both titles ranking after the "Masjid al-Haram" in Mecca. The mosque is located at the heart of Medina and is a major pilgrimage site that falls under the purview of the Custodian of the Two Holy Mosques.


title: Al-Masjid an-Nabawi

text: Muhammad was involved in the construction of the mosque. At the time, the land of Al-Masjid an-Nabawi belonged to two young orphans, Sahl and Suhayl, and when they learned that Muhammad wished to acquire their land to erect a mosque, they went to Muhammad and offered the land to him as a gift; Muhammad insisted on paying a price for the land because they were orphaned children. The price agreed upon was paid by Abu Ayyub al-Ansari, who thus became the endower or donor () of Al-Masjid an-Nabawi on behalf of, or in favor of, Muhammad. al-Ansari also accommodated Muhammad upon his arrival at Medina in 622.


title: Al-Masjid an-Nabawi

text: Originally an open-air building, the mosque served as a community center, a court of law, and a religious school. It contained a raised platform or pulpit ("minbar") for the people who taught the Quran and for Muhammad to give the Friday sermon ("khutbah"). Subsequent Islamic rulers greatly expanded and decorated the mosque, naming its walls, doors and minarets after themselves and their forefathers. After an expansion during the reign of the Umayyad caliph Al-Walid I, it now incorporates the final resting place of Muhammad and the first two Rashidun caliphs Abu Bakr and Umar. One of the most notable features of the site is the Green Dome in the south-east corner of the mosque, originally Aisha's house, where the tomb of Muhammad is located. Many pilgrims who perform the Hajj also go to Medina to visit ("Ziyarah") the Green Dome.


title: Al-Masjid an-Nabawi

text: In 1909, under the reign of Ottoman Sultan Abdul Hamid II, it became the first place in the Arabian Peninsula to be provided with electrical lights. From the 14th century, the Mosque was guarded by eunuchs, the last remaining guardians were photographed at the request of Prince Faisal bin Salman Al Saud, and in 2015 only five were left. It is generally open regardless of date or time, and has only been closed to visitors once in modern times, as Ramadan approached during the COVID-19 pandemic in 2020.


title: Al-Masjid an-Nabawi

text: The mosque was built by Muhammad in 622 AD after his arrival in Medina. Riding a camel called Qaswa, he arrived at the place where this mosque was built, which was being used as a burial ground. Refusing to accept the land as a gift from the two orphans, Sahl and Suhayl, who owned the land, he bought the land which was paid for by Abu Ayyub al-Ansari and it took seven months to complete the construction of the mosque. It measured . The roof which was supported by palm trunks was made of beaten clay and palm leaves. It was at a height of . The three doors of the mosque were the "Gate of Mercy" ( "Bab ar-Rahmah") to the south, "Gate of Gabriel" ( "Bab Jibril") to the west and "Gate of Women" ( "Bab an-Nisa") to the east. At this time point in the history of the Mosque, the qiblah wall was facing north to Jerusalem, and the Suffah was along the northern wall.


title: Al-Masjid an-Nabawi

text: In the year 7 AH, after the Battle of Khaybar, the mosque was expanded to on each side and three rows of columns were built beside the west wall, which became the place of praying. The mosque remained unaltered during the reign of the first Rashidun caliph Abu Bakr.


title: Al-Masjid an-Nabawi

text: The second Rashidun caliph Umar demolished all the houses around the mosque except those of Muhammad's wives to expand it. The new mosque's dimensions became . Sun-dried mud bricks were used to construct the walls of the enclosure. Besides strewing pebbles on the floor, the roof's height was increased to . Umar constructed three more gates for entrance. He also added the "Al Butayha" () for people to recite poetry.


title: Al-Masjid an-Nabawi

text: The third Rashidun caliph Uthman demolished the mosque in 649. Ten months were spent in building the new rectangular shaped mosque whose face was turned towards the Kaaba in Mecca. The new mosque measured . The number of gates as well as their names remained the same. The enclosure was made of stones laid in mortar. The palm trunk columns were replaced by stone columns which were joined by iron clamps. Teakwood was used in reconstructing the ceiling filza.


title: Al-Masjid an-Nabawi

text: In 707, the Umayyad caliph al-Walid I () renovated the mosque. It took three years for the work to be completed. Raw materials were procured from the Byzantine Empire. The area of the mosque was increased from the of Uthman's time to . A wall was built to segregate the mosque and the houses of the wives of Muhammad. The mosque was reconstructed in a trapezoid shape with the length of the longer side being . For the first time, porticoes were built in the mosque connecting the northern part of the structure to the sanctuary. Minarets were also built for the first time as al-Walid constructed four minarets around it.


title: Al-Masjid an-Nabawi

text: The Abbasid caliph al-Mahdi () extended the mosque to the north by . His name was also inscribed on the walls of the mosque. He also planned to remove six steps to the "minbar", but abandoned this idea, fearing damage to the wooden platforms on which they were built. According to an inscription of Ibn Qutaybah, the caliph al-Ma'mun () did "unspecified work" on the mosque. Al-Mutawakkil () lined the enclosure of Muhammad's tomb with marble. In 1269, the Mamluk Sultan Baibars sent dozens of artisans led by the eunuch emir Jamal al-Din Muhsin al-Salihi to rebuild the sanctuary, including enclosures around the tombs of Muhammad and of Fatima. The Mamluk sultan al-Ashraf Qansuh al-Ghuri () built a dome of stone over his grave in 1476.


title: Al-Masjid an-Nabawi

text: Sultan Suleiman the Magnificent (r. 1520-1566) rebuilt the east and west walls of the mosque, and added the northeastern minaret known as "Süleymaniyye". He added a new altar called Ahnaf next to Muhammad's altar, Shafi'iyya, and placed a new steel-covered dome on the tomb of Muhammad. Sultan Suleiman the Magnificent wrote the names of the Ottoman sultans from Osman Ghazi to himself (Kanuni) and revived the "Gate of Mercy" ("Bab ur-Rahme") or the west gate. The pulpit that is used today was built under Sultan Murad III (r. 1574-1595).


title: Al-Masjid an-Nabawi

text: In 1817, Sultan Mahmud II (r. 1808-1839) completed the construction of the "Purified Residence" ( "al-Rawdah al-Mutaharah" in Arabic and "Ravza-i Mutahhara" in Turkish) on the southeast side of the mosque and covered with a new dome. The dome was painted green in 1837 and has been known as the "Green Dome" ("Kubbe-i Khadra") ever since. Sultan Mahmud II's successor, Sultan Abdulmecid I (), took thirteen years to rebuild the mosque, beginning in 1849. Red stone bricks were used as the main material in reconstruction of the mosque. The floor area of the mosque was increased by .


title: Al-Masjid an-Nabawi

text: The entire mosque was reorganized except for the tomb of Muhammad, the three altars, the pulpit and the Suleymaniye minaret. On the walls, verses from the Quran were inscribed in Islamic calligraphy. On the northern side of the mosque, a "madrasah" was built for teaching the Qur'an. An ablution site was added to the north side. The prayer place on the south side was doubled in width, and covered with small domes. The interiors of the domes were decorated with verses from the Qur'an and couplets from the poem "Kaside-i Bürde". The kibla wall was covered with polished tiles with lines inscribed from the Qur'an. The places of prayer and courtyard were paved with marble and red stone. The fifth minaret, "Mecidiyye", was built to the west of the surrounded area. Following the "Desert Tiger" Fakhri Pasha's arrest by his own officers having resisted for 72 days after the end of the Siege of Medina on 10 January 1919, 550 years of Ottoman rule in the region came to an end.


title: Al-Masjid an-Nabawi

text: When Saud bin Abdul-Aziz took Medina in 1805, his followers, the Wahhabis, demolished nearly every tomb and dome in Medina in order to prevent their veneration, except the Green Dome. As per the sahih hadiths they considered the veneration of tombs and places thought to possess supernatural powers as an offence against "tawhid" and an act of "shirk". Muhammad's tomb was stripped of its gold and jewel ornaments, but the dome was preserved either because of an unsuccessful attempt to demolish its complex and hardened structure, or because some time ago Ibn Abd al-Wahhab, founder of the Wahhabi movement, wrote that he did not wish to see the dome destroyed.


title: Al-Masjid an-Nabawi

text: The Saudi takeover was characterized by events similar to those that took place in 1805 when the Prince Mohammed ibn Abdulaziz retook the city on 5 December 1925. After the foundation of the Kingdom of Saudi Arabia in 1932, the mosque underwent several major modifications. In 1951 King Abdulaziz (1932–1953) ordered demolitions around the mosque to make way for new wings to the east and west of the prayer hall, which consisted of concrete columns with pointed arches. Older columns were reinforced with concrete and braced with copper rings at the top. The "Suleymaniyya" and "Mecidiyye" minarets were replaced with two minarets in Mamluk revival style. Two additional minarets were erected to the northeast and northwest of the mosque. A library was built along the western wall to house historic Qurans and other religious texts.


title: Al-Masjid an-Nabawi

text: In 1974, King Faisal added 40,440 square metres (435,000 square feet) to the mosque. The area of the mosque was also expanded during the reign of King Fahd in 1985. Bulldozers were used to demolish buildings around the mosque. In 1992, when it was completed, the mosque took over 160,000 square meters (1.7 million square feet) of space. Escalators and 27 courtyards were among the additions to the mosque. A $6 billion project to increase the area of the mosque was announced in September 2012. After completion, the mosque should accommodate between 1.6 million to 2 million worshippers. In March of the following year, "Saudi Gazette" reported that demolition work had been mostly complete, including the demolition of ten hotels on the eastern side, in addition to houses and other utilities.


title: Al-Masjid an-Nabawi

text: The modern-day Masjid an-Nabawi is situated on a rectangular plot and is two stories tall. The Ottoman prayer hall, which is the oldest part of Masjid an-Nabawi, lies towards the south. It has a flat paved roof topped with 27 sliding domes on square bases. Holes pierced into the base of each dome illuminate the interior when the domes are closed. The sliding roof is closed during the afternoon prayer (Dhuhr) to protect the visitors. When the domes slide out on metal tracks to shade areas of the roof, they create light wells for the prayer hall. At these times, the courtyard of the Ottoman mosque is also shaded with umbrellas affixed to freestanding columns. The roof is accessed by stairs and escalators. The paved area around the mosque is also used for prayer, equipped with umbrella tents. The sliding domes and retractable umbrella-like canopies were designed by the German Muslim architect Mahmoud Bodo Rasch, his firm SL Rasch GmbH, and Buro Happold.


title: Al-Masjid an-Nabawi

text: The chamber adjacent to the "Rawdah" holds the tombs of Muhammad and two of his companions, father-in-laws and caliphs, Abu Bakr and Umar ibn al-Khattab. A fourth grave is reserved for ‘Īsā (, Jesus), as Muslims believe that he will return and will be buried at the site. The site is covered by the Green Dome. It was constructed in 1817 CE during the reign of the Ottoman sultan Mahmud II and painted green in 1837 CE.


title: Al-Masjid an-Nabawi

text: The "Rawḍah ash-Sharifah" () is an area between the minbar and burial chamber of Muhammad. It is regarded as one of the "Riyāḍ al-Jannah" (). A green carpet was used to distinguish the area from the red carpet used in the rest of the mosque, though it is now also green. Considering visiting Madinah and performing the Ziyarah, Muhammad said:


title: Al-Masjid an-Nabawi

text: “When a person stands at my grave reciting blessings on me, I hear it; and whoever calls for blessings on me in any other place, his every need in this world and in the hereafter is fulfilled and on the day of Qiyamah I shall be his witness and intercessor.”


title: Al-Masjid an-Nabawi

text: There are two mihrabs or niches indicating the qibla () in the mosque, one was built by Muhammad and another was built by the third Rashidun caliph Uthman. The one built by the latter was larger than that of Muhammad's and acts as the functional mihrab, whereas Muhammad's mihrab is a "commemorative" mihrab. Besides the "mihrab", the mosque also has other niches which act as indicators for praying. This includes the "Miḥrâb Fâṭimah" () or "Miḥrāb aṫ-Ṫahajjud" (), which was built by Muhammad for the "Ṫahajjud" (late-night) prayer ().


title: Al-Masjid an-Nabawi

text: The original "minbar" () used by Muhammad was a block of date palm wood. This was replaced by him with a tamarisk one, which had dimensions of . In 629 CE, a three staired ladder was added to it. The first two caliphs, Abu Bakr and Umar, did not use the third step as a sign of respect to Muhammad, but the third caliph Uthman placed a fabric dome over it and the rest of the stairs were covered with ebony. The "minbar" was replaced by Baybars I, by Shaykh al-Mahmudi in 1417, and by Qaitbay in 1483. In 1590 it was replaced by the Ottoman sultan Murad III with a marble "minbar", while Qaytbay's minbar was moved to the Quba Mosque. As of 2013, the Ottoman minbar is still used in the mosque.


title: Al-Masjid an-Nabawi

text: The first minarets (four in number) of high were constructed by Umar. In 1307, a minaret titled "Bab al-Salam" was added by Muhammad ibn Kalavun which was renovated by Mehmed IV. After the renovation project of 1994, there were ten minarets which were high. The minarets' upper, bottom and middle portion are cylindrical, octagonal and square shaped respectively.


title: Spanish conquest of the Aztec Empire

text: The Spanish conquest of the Aztec Empire, also known as the Conquest of Mexico or the Spanish-Aztec War (1519–21), was one of the primary events in the Spanish colonization of the Americas. There are multiple 16th-century narratives of the events by Spanish conquistadors, their indigenous allies, and the defeated Aztecs. It was not solely a contest between a small contingent of Spaniards defeating the Aztec Empire but rather the creation of a coalition of Spanish invaders with tributaries to the Aztecs, and most especially the Aztecs' indigenous enemies and rivals. They combined forces to defeat the Mexica of Tenochtitlan over a two-year period. For the Spanish, the expedition to Mexico was part of a project of Spanish colonization of the New World after twenty-five years of permanent Spanish settlement and further exploration in the Caribbean.


title: Spanish conquest of the Aztec Empire

text: Historical sources for the conquest of Mexico recount some of the same events in both Spanish and indigenous sources. Others, however, are unique to a particular primary source or group narrating the event. Individuals and groups laud their own accomplishments, while often denigrating or ignoring those of their opponents or their allies or both.


title: Spanish conquest of the Aztec Empire

text: Following an earlier expedition to Yucatán led by Juan de Grijalva in 1518, Spanish conquistador Hernán Cortés led an expedition ("entrada") to Mexico. The next year, Cortés and his retinue set sail for Mexico. The Spanish campaign against the Aztec Empire had its final victory on 13 August 1521, when a coalition army of Spanish forces and native Tlaxcalan warriors led by Cortés and Xicotencatl the Younger captured the emperor Cuauhtémoc and Tenochtitlan, the capital of the Aztec Empire. The fall of Tenochtitlan marks the beginning of Spanish rule in central Mexico, and they established their capital of Mexico City on the ruins of Tenochtitlan.


title: Spanish conquest of the Aztec Empire

text: Cortés made alliances with tributary city-states ("altepetl") of the Aztec Empire as well as their political rivals, particularly the Tlaxcaltecs and Tetzcocans, a former partner in the Aztec Triple Alliance. Other city-states also joined, including Cempoala and Huejotzingo and polities bordering Lake Texcoco, the inland lake system of the Valley of Mexico. Particularly important to the Spanish success was a multilingual (Nahuatl, a Maya dialect, and Spanish) Nahua-speaking woman enslaved by the Mayas, known to the Spanish conquistadors as Doña Marina, and later as La Malinche. After eight months of battles and negotiations, which overcame the diplomatic resistance of the Aztec Emperor Moctezuma II to his visit, Cortés arrived in Tenochtitlan on 8 November 1519, where he took up residence with fellow Spaniards and their indigenous allies. When news reached Cortés of the death of several of his men during the Aztec attack on the Totonacs in Veracruz, Cortés claims that he took Motecuhzoma captive. Capturing the cacique or indigenous ruler was a standard operating procedure for Spaniards in their expansion in the Caribbean, so capturing Motecuhzoma had considerable precedent but modern scholars are skeptical that Cortés and his countrymen took Motecuhzoma captive at this time. They had great incentive to claim they did, owing to the laws of Spain at this time, but critical analysis of their personal writings suggest Motecuhzoma was not taken captive until a much later date.


title: Spanish conquest of the Aztec Empire

text: When Cortés left Tenochtitlan to return to the coast and deal with the threat of the expedition of Pánfilo de Narváez, Cortés left Pedro de Alvarado in charge of Tenochtitlan. Cortés left with a small army to the coast with the plan of attacking during the night. After defeating Narváez's fleet, Cortés convinced most of his enemy's crew to go with him by promising great riches. Upon reaching Tenochtitlan, Cortés and the new enlarged force received the message that "the Aztec had risen against the Spanish garrison" during a religious celebration. Alvarado ordered his army to attack the unarmed crowd; he later claims that the Aztecs had used the celebration to cover up a counterattack. Cortés realized that the defeat was imminent and decided to escape yet, the Aztecs attacked. The Massacre is most known as the Noche Triste (the sorrowful night) about "400 Spaniards, 4000 native allies and many horses [were killed] before reaching the mainland". Moctezuma was killed, although the sources do not agree on who killed him. According to one account, when Moctezuma, now seen by the population as a mere puppet of the invading Spaniards, attempted to calm the outraged populace, he was killed by a projectile. According to an indigenous account, the Spanish killed Moctezuma. Cortés had returned to Tenochtitlan and his men fled the capital city during the Noche Triste in June 1520. The Spanish, Tlaxcalans and reinforcements returned a year later on 13 August 1521 to a civilization that had been weakened by famine and smallpox. This made it easier to conquer the remaining Aztecs. The Spaniards' victory is attributed to their technological advances and the Aztec empire's vulnerability due to the smallpox spread. As a result, the Aztec's tactics countering the Spaniard's advanced technology is understated. According to Hassig, "It is true that cannons, guns, crossbows, steel blades, horses and war dogs were advanced on the Aztecs' weaponry. But the advantage these gave a few hundred Spanish soldiers was not overwhelming." In the words of Restall, "Spanish weapons were useful for breaking the offensive lines of waves of indigenous warriors, but this was no formula for conquest ... rather, it was a formula for survival, until Spanish and indigenous reinforcements arrived."


title: Spanish conquest of the Aztec Empire

text: The integration of the indigenous allies, essentially, those from Tlaxcala and Texcoco, into the Spanish army played a crucial role in the conquest, yet other factors paved the path for the Spaniards' success. For instance, the Spaniards' timing of entry, the compelling ideologies of both groups, and the Spanish unfamiliarity with the Aztec Empire. Therefore, the Spaniards lacked a sense of danger and power structure within the empire. "A direct attack on a city as mighty as Tenochtitlan was unlikely and unexpected" from the enemy empires. As well, it was very uncommon that an attacking army would come unannounced. In addition, aside from the infantry and the allies' role in the Spanish conquest, cavalry was the "arm of decision in the conquest" and "the key ingredient in the Spanish forces".


title: Spanish conquest of the Aztec Empire

text: Many of those on the Cortés expedition of 1519 had never seen combat before, including Cortés. A whole generation of Spaniards later participated in expeditions in the Caribbean and Tierra Firme (Central America), learning strategy and tactics of successful enterprises. The Spanish conquest of Mexico had antecedents with established practices.


title: Spanish conquest of the Aztec Empire

text: The fall of the Aztec Empire was the key event in the formation of the Spanish Empire overseas, with New Spain, which later became Mexico.


title: Spanish conquest of the Aztec Empire

text: The conquest of Mexico, the initial destruction of the great pre-Columbian civilizations, is a significant event in world history. The conquest was well documented by a variety of sources with differing points of view, including indigenous accounts, by both allies and opponents. Accounts by the Spanish conquerors exist from the first landfall at Veracruz, Mexico (on Good Friday, 22 April 1519) to the final victory over the Mexica in Tenochtitlan on 13 August 1521. Notably, the accounts of the conquest, Spanish and indigenous alike, have biases and exaggerations. Some, though not all, Spanish accounts downplay the support of their indigenous allies. Conquerors' accounts exaggerate individual contributions to the Conquest at the expense of their comrades, while indigenous allies' accounts stress their loyalty and importance to victory for the Spanish. These accounts are similar to Spanish conquerors' accounts contained in petitions for rewards, known as "benemérito" petitions.


title: Spanish conquest of the Aztec Empire

text: Two lengthy accounts from the defeated indigenous viewpoint were created under the direction of Spanish friars, Franciscan Bernardino de Sahagún and Dominican Diego Durán, using indigenous informants.


title: Spanish conquest of the Aztec Empire

text: The first Spanish account of the conquest was written by lead conqueror Hernán Cortés, who sent a series of letters to the Spanish monarch Charles V, giving a contemporary account of the conquest from his point of view, in which he justified his actions. These were almost immediately published in Spain and later in other parts of Europe. Much later, Spanish conqueror Bernal Díaz del Castillo, a well-seasoned participant in the conquest of Central Mexico, wrote what he called "The True History of the Conquest of New Spain", countering the account by Cortés's official biographer, Francisco López de Gómara. Bernal Díaz's account had begun as a "benemérito" petition for rewards but he expanded it to encompass a full history of his earlier expeditions in the Caribbean and Tierra Firme and the conquest of the Aztec. A number of lower rank Spanish conquerors wrote "benemérito" petitions to the Spanish Crown, requesting rewards for their services in the conquest, including Juan Díaz, Andrés de Tapia, García del Pilar, and Fray Francisco de Aguilar. Cortés's right-hand man, Pedro de Alvarado did not write at any length about his actions in the New World, and died as a man of action in the Mixtón War in 1542. Two letters to Cortés about Alvarado's campaigns in Guatemala are published in "The Conquistadors".


title: Spanish conquest of the Aztec Empire

text: The chronicle of the so-called "Anonymous Conqueror" was written sometime in the sixteenth century, entitled in an early twentieth-century translation to English as Narrative of Some Things of New Spain and of the Great City of Temestitan (i.e. Tenochtitlan). Rather than it being a petition for rewards for services, as many Spanish accounts were, the Anonymous Conqueror made observations about the indigenous situation at the time of the conquest. The account was used by eighteenth-century Jesuit Francisco Javier Clavijero in his descriptions of the history of Mexico.


title: Spanish conquest of the Aztec Empire

text: On the indigenous side, the allies of Cortés, particularly the Tlaxcalans, wrote extensively about their services to the Spanish Crown in the conquest, arguing for special privileges for themselves. The most important of these are the pictorial Lienzo de Tlaxcala and the "Historia de Tlaxcala" by Diego Muñoz Camargo. Less successfully, the Nahua allies from Huexotzinco (or Huejotzinco) near Tlaxcala argued that their contributions had been overlooked by the Spanish. In a letter in Nahuatl to the Spanish Crown, the indigenous lords of Huexotzinco lay out their case in for their valorous service. The letter has been published in Nahuatl and English translation by James Lockhart in "We People Here: Nahuatl Accounts of the Conquest of Mexico" in 1991. Texcoco patriot and member of a noble family there, Fernando Alva Ixtlilxochitl, likewise petitioned the Spanish Crown, in Spanish, saying that Texcoco had not received sufficient rewards for their support of the conquistadors, particularly after the Spanish were forced out of Tenochtitlan.


title: Spanish conquest of the Aztec Empire

text: The best-known indigenous account of the conquest is Book 12 of Bernardino de Sahagún's "General History of the Things of New Spain" and published as the Florentine Codex, in parallel columns of Nahuatl and Spanish, with pictorials. Less well-known is Sahagún's 1585 revision of the conquest account, which shifts from the indigenous viewpoint entirely and inserts at crucial junctures passages lauding the Spanish and in particular Hernán Cortés. Another indigenous account compiled by a Spanish friar is Dominican Diego Durán's "The History of the Indies of New Spain", from 1581, with many color illustrations.


title: Spanish conquest of the Aztec Empire

text: A text from the Nahua point of view, the Anales de Tlatelolco, an early indigenous account in Nahuatl, perhaps from 1540, remained in indigenous hands until it was published. An extract of this important manuscript was published in 1991 by James Lockhart in Nahuatl transcription and English translation. A popular anthology in English for classroom use is Miguel León-Portilla's, "The Broken Spears: The Aztec Accounts of the Conquest of Mexico" from 1992. Not surprisingly, many publications and republications of sixteenth-century accounts of the conquest of Mexico appeared around 1992, the 500th anniversary of Christopher Columbus's first voyage, when scholarly and popular interest in first encounters surged.


title: Spanish conquest of the Aztec Empire

text: A popular and enduring narrative of the Spanish campaign in central Mexico is by New England-born nineteenth-century historian William Hickling Prescott. His "History of the Conquest of Mexico", first published in 1843, remains an important unified narrative synthesis of the conquest. Prescott read and used all the formal writings from the sixteenth century, although few had been published by the mid-nineteenth century when he was writing. It is likely that a 1585 revision of Bernardino de Sahagún's account of the conquest survives today only in the form of a copy because it was made in Spain for Prescott's project from a now-lost original. Although scholars of the modern era point out its biases and shortcomings, "there is nowhere they can get as good a unified narrative of the main events, crises, and course of the Mexican conquest as Prescott's version."


title: Spanish conquest of the Aztec Empire

text: In the sources recorded by Franciscan Bernardino de Sahagún and Dominican Diego Durán in the mid to late sixteenth century, there are accounts of events that were interpreted as supernatural omens of the conquest. These two accounts are full-blown narratives from the viewpoint of the Spanish opponents. Most first-hand accounts about the conquest of the Aztec Empire were written by Spaniards: Hernán Cortés' letters to Charles V, Holy Roman Emperor and the first-person narrative of Bernal Díaz del Castillo, "The True History of the Conquest of New Spain". The primary sources from the native people affected as a result of the conquest are seldom used, because they tend to reflect the views of a particular native group, such as the Tlaxcalans. Indigenous accounts were written in pictographs as early as 1525. Later accounts were written in the native tongue of the Aztec and other native peoples of central Mexico, Nahuatl.


title: Spanish conquest of the Aztec Empire

text: The native texts of the defeated Mexica narrating their version of the conquest describe eight omens that were believed to have occurred nine years prior to the arrival of the Spanish from the Gulf of Mexico.


title: Spanish conquest of the Aztec Empire

text: In 1510, Aztec Emperor Moctezuma II was visited by Nezahualpilli, who had a reputation as a great seer, as well as being the "tlatoani" of Texcoco. Nezahualpilli warned Moctezuma that he must be on guard, for in a few years Aztec cities would be destroyed. Before leaving, he said that there would be omens for Moctezuma to know that what he has been told is true. Over the years, and especially after Nezhualpilli's death in 1515, several supernatural omens appeared.


title: Spanish conquest of the Aztec Empire

text: Additionally, the Tlaxcala saw a "radiance that shone in the east every morning three hours before sunrise", and a "whirlwind of dust" from the volcano Matlalcueye. According to Diaz, "These "Caciques" also told us of a tradition they had heard from their ancestors, that one of the idols which they particularly worshipped had prophesied the coming of men from distant lands in the direction of the sunrise, who would conquer them and rule them." Some accounts would claim that this idol or deity was Quetzalcoatl, and that the Aztecs were defeated because they believed the Spanish were supernatural and didn't know how to react, although whether or not the Aztecs really believed that is debatable.


title: Spanish conquest of the Aztec Empire

text: Omens were extremely important to the Aztecs, who believed that history repeated itself. A number of modern scholars cast doubt on whether such omens occurred or whether they were "ex post facto" (retrospective) creations to help the Mexica explain their defeat. Some scholars contend that "the most likely interpretation of the story of these portents is that some, if not all, had occurred" but concede that it is very likely that "clever Mexicans and friars, writing later of the Mexican empire, were happy to link those memories with what they know occurred in Europe.


title: Spanish conquest of the Aztec Empire

text: Many sources depicting omens and the return of old Aztec gods, including those supervised by Spanish priests, were written after the fall of Tenochtitlan in 1521. Some ethnohistorians say that when the Spanish arrived native peoples and their leaders did not view them as supernatural in any sense but rather as simply another group of powerful outsiders. According to some historians, Moctezuma responded rationally to the Spanish invasion. These historians believe this means that Moctezuma did not think the Spanish were supernatural. Many Spanish accounts incorporated omens to emphasize what they saw as the preordained nature of the conquest and their success as Spanish destiny. This means that native emphasis on omens and bewilderment in the face of invasion "may be a postconquest interpretation by informants who wished to please the Spaniards or who resented the failure of Montezuma and of the warriors of Tenochtitlan to provide leadership." Hugh Thomas concludes that Moctezuma was confused and ambivalent about whether Cortés was a god or the ambassador of a great king in another land. Because the Spaniards arrived in 1519, Moctezuma knew this was the year of Ce Acatl, which is the year Quetzalcoatl was promised to return. Previously, during Juan de Grijalva's expedition, Moctezuma believed that those men were heralds of Quetzalcoatl, as Moctezuma, as well as everyone else in the Aztec Empire, were to believe that eventually, Quetzalcoatl will return. Moctezuma even had glass beads that were left behind by Grijalva brought to Tenochtitlan and they were regarded as sacred religious relics.


title: Spanish conquest of the Aztec Empire

text: The Spanish had established a permanent settlement on the island of Hispaniola in 1493 on the second voyage of Christopher Columbus. There were further Spanish explorations and settlements in the Caribbean and the Spanish Main, seeking wealth in the form of gold and access to indigenous labor to mine gold and other manual labor. Twenty-five years after the first Spanish settlement in the New World, expeditions of exploration were sent to the coast of Mexico.


title: Spanish conquest of the Aztec Empire

text: In 1517, Cuban governor Diego Velázquez commissioned a fleet of three ships under the command of Hernández de Córdoba to sail west and explore the Yucatán peninsula. Córdoba reached the coast of Yucatán. The Mayans at Cape Catoche invited the Spanish to land, and the conquistadors read the Requirement of 1513 to them, which offered the natives the protection of the King of Spain, if they would submit to him. Córdoba took two prisoners, who adopted the baptized names of Melchor and Julián and became interpreters. Later, the two prisoners, being misled or misinterpreting the language gave information to the Spanish conquistadors that there was plenty of gold up for grabs. On the western side of the Yucatán Peninsula, the Spanish were attacked at night by Maya chief Mochcouoh, a battle in which 50 men were killed. Córdoba was mortally wounded and only a remnant of his crew returned to Cuba.


title: Spanish conquest of the Aztec Empire

text: At that time, Yucatán was briefly explored by the conquistadors, but the Spanish conquest of Yucatán with its many independent city-state polities of the Late Postclassic Maya civilization came many years after the Spaniards' and their loyal indigenous allies' rapid conquest of Central Mexico (1519–21). With the help of tens of thousands of Xiu Mayan warriors, it would take more than 170 years for the Spanish to establish full control of the Maya homelands, which extended from northern Yucatán to the central lowlands region of El Petén and the southern Guatemalan highlands. The end of this latter campaign is generally marked by the downfall of the Maya state based at Tayasal in the Petén region, in 1697.


title: Spanish conquest of the Aztec Empire

text: Even before Juan de Grijalva returned to Spain, Velázquez decided to send a third and even larger expedition to explore the Mexican coast. Hernán Cortés, then one of Velázquez's favorites and brother-in-law, was named as the commander, which created envy and resentment among the Spanish contingent in the Spanish colony. Licenses for expeditions allowed the Crown to retain sovereignty over newly conquered lands while not risking its own assets in the enterprise. Anyone willing to make a financial contribution could potentially gain even more wealth and power. Men who brought horses, "caballeros", received two shares of the spoils, one for military service, another because of the horse. Cortés invested a considerable part of his personal fortune and probably went into debt to borrow additional funds. Velázquez may have personally contributed nearly half the cost of the expedition.


title: Spanish conquest of the Aztec Empire

text: In an agreement signed on 23 October 1518, Governor Velázquez restricted the expedition led by Cortés to exploration and trade, so that conquest and settlement of the mainland might occur under his own command, once he had received the permission necessary to do so which he had already requested from the Crown. In this way, Velázquez sought to ensure title to the riches and laborers discovered. However, armed with the knowledge of Castilian law that he had likely gained as a notary in Valladolid, Cortés managed to free himself of Velázquez's authority by presenting Velázquez as a tyrant acting in his own self-interest, and not in the interest of the Crown. The men under Cortés also named him military leader and chief magistrate (judge) of the expedition.


title: Spanish conquest of the Aztec Empire

text: Velázquez himself must have been keenly aware that whoever conquered the mainland for Spain would gain fame, glory and fortune to eclipse anything that could be achieved in Cuba. Thus, as the preparations for departure drew to a close, the governor became suspicious that Cortés would be disloyal to him and try to commandeer the expedition for his own purposes, namely to establish himself as governor of the colony, independent of Velázquez's control.


title: Spanish conquest of the Aztec Empire

text: Therefore, Velázquez sent Luis de Medina with orders to replace Cortés. However, Cortés's brother-in-law allegedly had Medina intercepted and killed. The papers that Medina had been carrying were sent to Cortés. Thus warned, Cortés accelerated the organization and preparation of his expedition.


title: Spanish conquest of the Aztec Empire

text: Velázquez arrived at the dock in Santiago de Cuba in person, "he and Cortés again embraced, with a great exchange of compliments", before Cortés set sail for Trinidad, Cuba. Velázquez then sent orders for the fleet to be held and Cortés taken prisoner. Nevertheless, Cortés set sail, beginning his expedition with the legal status of a mutineer.


title: Spanish conquest of the Aztec Empire

text: Cortés's contingent consisted of 11 ships carrying about 630 men (including 30 crossbowmen and 12 arquebusiers, an early form of firearm), a doctor, several carpenters, at least eight women, a few hundred Arawaks from Cuba and some Africans, both freedmen and slaves. Although modern usage often calls the European participants "soldiers", the term was never used by these men themselves in any context, something that James Lockhart realized when analyzing sixteenth-century legal records from conquest-era Peru.


title: Spanish conquest of the Aztec Empire

text: Cortés spent some time at the island of Cozumel, on the east coast of Yucatán, trying to convert the locals to Christianity, something that provided mixed results. While at Cozumel, Cortés heard reports of other white men living in the Yucatán. Cortés sent messengers to these reported Spaniards, who turned out to be the survivors of a Spanish shipwreck that had occurred in 1511, Gerónimo de Aguilar and Gonzalo Guerrero.


title: Spanish conquest of the Aztec Empire

text: Aguilar petitioned his Maya chieftain to be allowed to join his former countrymen, and he was released and made his way to Cortés's ships. Now quite fluent in Maya, as well as some other indigenous languages, proved to be a valuable asset for Cortés as a translator – a skill of particular significance to the later conquest of the Aztec Empire that was to be the end result of Cortés's expedition. According to Bernal Díaz, Aguilar relayed that before coming, he had attempted to convince Guerrero to leave as well. Guerrero declined on the basis that he was by now well-assimilated with the Maya culture, had a Maya wife and three children, and he was looked upon as a figure of rank within the Maya state of Chetumal, where he lived. Although Guerrero's later fate is somewhat uncertain, it appears that for some years he continued to fight alongside the Maya forces against Spanish incursions, providing military counsel and encouraging resistance; it is speculated that he may have been killed in a later battle.


title: Spanish conquest of the Aztec Empire

text: After leaving Cozumel, Cortés continued round the tip of the Yucatán Peninsula and landed at Potonchán, where there was little gold. After defeating the local natives in two battles, he discovered a far more valuable asset in the form of a woman whom Cortés would have christened Marina. She is often known as La Malinche and also sometimes called "Malintzin" or Malinalli. Later, the Aztecs would come to call Cortés "Malintzin" or La Malinche by dint of his close association with her. Bernal Díaz del Castillo wrote in his account "The True History of the Conquest of New Spain" that Marina was "truly a great princess". Later, the honorific Spanish title of "doña" would be added to her baptized name.


title: Spanish conquest of the Aztec Empire

text: Cortés had stumbled upon one of the keys to realizing his ambitions. He would speak to Gerónimo de Aguilar in Spanish who would then translate into Mayan for Marina. She would then translate from Mayan to Nahuatl. With this pair of translators, Cortés could now communicate to the Aztecs. How effectively is still a matter of speculation, since Marina did not speak the dialect of the Aztecs, nor was she familiar with the protocols of the Aztec nobility, who were renowned for their flowery, flattering talk. Doña Marina quickly learned Spanish, and became Cortés's primary interpreter, confidant, consort, cultural translator, and the mother of his first son, Martin. Until Cortés's marriage to his second wife, a union which produced a legitimate son whom he also named Martin, Cortés's natural son with Marina was the heir of his envisaged fortunes.


title: Spanish conquest of the Aztec Empire

text: Native speakers of Nahuatl would call her "Malintzin". This name is the closest approximation possible in Nahuatl to the sound of Spanish "Marina". Over time, "La Malinche" (the modern Spanish cognate of "Malintzin") became a term for a traitor to one's people. To this day, the word "malinchista" is used by Mexicans to denote one who apes the language and customs of another country. It would not be until the late 20th century that a few feminist writers and academics in Mexico would attempt to rehabilitate La Malinche as a woman who made the best of her situation and became, in many respects, a powerful woman.


title: Spanish conquest of the Aztec Empire

text: Cortés landed his expedition force on the coast of the modern day state of Veracruz in April 1519. During this same period, soon after he arrived, Cortés was welcomed by representatives of the Aztec Emperor, Moctezuma II. Gifts were exchanged, and Cortés attempted to frighten the Aztec delegation with a display of his firepower.


title: Spanish conquest of the Aztec Empire

text: Faced with imprisonment or death for defying the governor, Cortés' only alternative was to continue his enterprise in the hope of redeeming himself and his men with the Spanish Crown. To do this, his men established a settlement called La Villa Rica de la Vera Cruz, or "True Cross", since they arrived on Maundy Thursday and landed on Good Friday. The legally constituted "town council of Villa Rica" then promptly offered him the position of adelantado, or Chief Justice and Captain-General.


title: Spanish conquest of the Aztec Empire

text: This strategy was not unique. Velásquez had used this same legal mechanism to free himself from Diego Columbus' authority in Cuba. In being named "adelantado" by a duly constituted cabildo, Cortés was able to free himself from Velásquez's authority and continue his expedition. To ensure the legality of this action, several members of his expedition, including Francisco Montejo and Alonso Hernandez Puertocarrero, returned to Spain to seek acceptance of the cabildo's declaration with King Charles.


title: Spanish conquest of the Aztec Empire

text: Cortés learned of an indigenous settlement called Cempoala and marched his forces there. On their arrival in Cempoala, they were greeted by 20 dignitaries and cheering townsfolk. Cortés quickly persuaded the Totonac chiefs to rebel against the Aztecs, taking prisoner five of Moctezuma's tax collectors. The Totonacs also helped Cortés build the town of Villa Rica de la Vera Cruz, which was the starting point for his attempt to conquer the Aztec Empire.


title: Spanish conquest of the Aztec Empire

text: Hearing of the rebellion, more ambassadors from the Aztec Emperor returned to see Cortés, bearing gifts of "gold and cloth", in thankfulness for Cortés freeing his tax collectors. Montezuma also told Cortés, he was certain the Spanish were of "his own race" and had arrived as "his ancestors had foretold". As Cortés told his men, the natives "think of us as gods, or godlike beings."


title: Spanish conquest of the Aztec Empire

text: Although they attempted to dissuade Cortés from visiting Tenochtitlan, the lavish gifts and the polite, welcoming remarks only encouraged "El Caudillo" to continue his march towards the capital of the empire.


title: Spanish conquest of the Aztec Empire

text: Men still loyal to the governor of Cuba planned to seize a ship and escape to Cuba, but Cortés moved swiftly to squash their plans. Two leaders were condemned to be hanged; two were lashed, and one had his foot mutilated. To make sure such a mutiny did not happen again, he decided to scuttle his ships.


title: Spanish conquest of the Aztec Empire

text: There is a popular misconception that the ships were burned rather than sunk. This misconception has been attributed to the reference made by Cervantes de Salazár in 1546, as to Cortés burning his ships. This may have also come from a mistranslation of the version of the story written in Latin.


title: Spanish conquest of the Aztec Empire

text: With all of his ships scuttled, Cortés effectively stranded the expedition in central Mexico. However, it did not completely end the aspirations of those members of his company who remained loyal to the governor of Cuba. Cortés then led his band inland towards Tenochtitlan.


title: Spanish conquest of the Aztec Empire

text: In addition to the Spaniards, Cortés' force now included 40 Cempoalan warrior chiefs and at least 200 other natives whose task was to drag the cannon and carry supplies. The Cempoalans were accustomed to the hot climate of the coast, but they suffered immensely from the cold of the mountains, the rain, and the hail as they marched towards Tenochtitlan.