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Photovoltaics

Photovoltaics (PV) is the conversion of light into electricity using semiconducting materials that exhibit the photovoltaic effect, a phenomenon studied in physics, photochemistry, and electrochemistry. The photovoltaic effect is commercially used for electricity generation and as photosensors.

A photovoltaic system employs solar modules, each comprising a number of solar cells, which generate electrical power. PV installations may be ground-mounted, rooftop-mounted, wall-mounted or floating. The mount may be fixed or use a solar tracker to follow the sun across the sky.

Photovoltaic technology helps to mitigate climate change because it emits much less carbon dioxide than fossil fuels. Solar PV has specific advantages as an energy source: once installed, its operation does not generate any pollution or any greenhouse gas emissions; it shows scalability in respect of power needs and silicon has large availability in the Earth's crust, although other materials required in PV system manufacture such as silver may constrain further growth in the technology. Other major constraints identified include competition for land use. The use of PV as a main source requires energy storage systems or global distribution by high-voltage direct current power lines causing additional costs, and also has a number of other specific disadvantages such as variable power generation which have to be balanced. Production and installation does cause some pollution and greenhouse gas emissions, though only a fraction of the emissions caused by fossil fuels.

Photovoltaic systems have long been used in specialized applications as stand-alone installations and grid-connected PV systems have been in use since the 1990s. Photovoltaic modules were first mass-produced in 2000, when the German government funded a one hundred thousand roof program. Decreasing costs has allowed PV to grow as an energy source. This has been partially driven by massive Chinese government investment in developing solar production capacity since 2000, and achieving economies of scale. Improvements in manufacturing technology and efficiency have also led to decreasing costs. Net metering and financial incentives, such as preferential feed-in tariffs for solar-generated electricity, have supported solar PV installations in many countries. Panel prices dropped by a factor of 4 between 2004 and 2011. Module prices dropped by about 90% over the 2010s.

In 2022, worldwide installed PV capacity increased to more than 1 terawatt (TW) covering nearly two percent of global electricity demand. After hydro and wind powers, PV is the third renewable energy source in terms of global capacity. In 2022, the International Energy Agency expected a growth by over 1 TW from 2022 to 2027. In some instances, PV has offered the cheapest source of electrical power in regions with a high solar potential, with a bid for pricing as low as 0.015 US$/kWh in Qatar in 2023. In 2023, the International Energy Agency stated in its World Energy Outlook that '[f]or projects with low cost financing that tap high quality resources, solar PV is now the cheapest source of electricity in history.

Etymology
The term "photovoltaic" comes from the Greek φῶς meaning "light", and from "volt", the unit of electromotive force, the volt, which in turn comes from the last name of the Italian physicist Alessandro Volta, inventor of the battery (electrochemical cell). The term "photovoltaic" has been in use in English since 1849.

History
In 1989, the German Research Ministry initiated the first ever program to finance PV roofs (2200 roofs). A program led by Walter Sandtner in Bonn, Germany.

In 1994, Japan followed in their footsteps and conducted a similar program with 539 residential PV systems installed. Since, many countries have continued to produce and finance PV systems in an exponential speed.

Solar cells
Photovoltaics are best known as a method for generating electric power by using solar cells to convert energy from the sun into a flow of electrons by the photovoltaic effect.

Solar cells produce direct current electricity from sunlight which can be used to power equipment or to recharge batteries. The first practical application of photovoltaics was to power orbiting satellites and other spacecraft, but today the majority of photovoltaic modules are used for grid-connected systems for power generation. In this case an inverter is required to convert the DC to AC. There is also a smaller market for stand alone systems for remote dwellings, boats, recreational vehicles, electric cars, roadside emergency telephones, remote sensing, and cathodic protection of pipelines.

Photovoltaic power generation employs solar modules composed of a number of solar cells containing a semiconductor material. Copper solar cables connect modules (module cable), arrays (array cable), and sub-fields. Because of the growing demand for renewable energy sources, the manufacturing of solar cells and photovoltaic arrays has advanced considerably in recent years.

Cells require protection from the environment and are usually packaged tightly in solar modules.

Photovoltaic module power is measured under standard test conditions (STC) in "Wp" (watts peak). The actual power output at a particular place may be less than or greater than this rated value, depending on geographical location, time of day, weather conditions, and other factors. Solar photovoltaic array capacity factors are typically under 25% when not coupled with storage, which is lower than many other industrial sources of electricity.

Performance and degradation

Module performance is generally rated under standard test conditions (STC): irradiance of 1,000 W/m2, solar spectrum of AM 1.5 and module temperature at 25 °C. The actual voltage and current output of the module changes as lighting, temperature and load conditions change, so there is never one specific voltage at which the module operates. Performance varies depending on geographic location, time of day, the day of the year, amount of solar irradiance, direction and tilt of modules, cloud cover, shading, soiling, state of charge, and temperature. Performance of a module or panel can be measured at different time intervals with a DC clamp meter or shunt and logged, graphed, or charted with a chart recorder or data logger.

For optimum performance, a solar panel needs to be made of similar modules oriented in the same direction perpendicular to direct sunlight. Bypass diodes are used to circumvent broken or shaded panels and optimize output. These bypass diodes are usually placed along groups of solar cells to create a continuous flow.

Electrical characteristics include nominal power (PMAX, measured in W), open-circuit voltage (VOC), short-circuit current (ISC, measured in amperes), maximum power voltage (VMPP), maximum power current (IMPP), peak power (watt-peak, Wp), and module efficiency (%).

Open-circuit voltage or VOC is the maximum voltage the module can produce when not connected to an electrical circuit or system. VOC can be measured with a voltmeter directly on an illuminated module's terminals or on its disconnected cable.

The peak power rating, Wp, is the maximum output under standard test conditions (not the maximum possible output). Typical modules, which could measure approximately 1 x, will be rated from as low as 75 W to as high as 600 W, depending on their efficiency. At the time of testing, the test modules are binned according to their test results, and a typical manufacturer might rate their modules in 5 W increments, and either rate them at +/- 3%, +/-5%, +3/-0% or +5/-0%.

Influence of temperature
The performance of a photovoltaic (PV) module depends on the environmental conditions, mainly on the global incident irradiance G in the plane of the module. However, the temperature T of the p–n junction also influences the main electrical parameters: the short circuit current ISC, the open circuit voltage VOC and the maximum power Pmax. In general, it is known that VOC shows a significant inverse correlation with T, while for ISC this correlation is direct, but weaker, so that this increase does not compensate for the decrease in VOC. As a consequence, Pmax decreases when T increases. This correlation between the power output of a solar cell and the working temperature of its junction depends on the semiconductor material, and is due to the influence of T on the concentration, lifetime, and mobility of the intrinsic carriers, i.e., electrons and gaps. inside the photovoltaic cell.

Temperature sensitivity is usually described by temperature coefficients, each of which expresses the derivative of the parameter to which it refers with respect to the junction temperature. The values of these parameters, which can be found in any data sheet of the photovoltaic module, are the following:

- β: VOC variation coefficient with respect to T, given by ∂VOC/∂T.

- α: Coefficient of variation of ISC with respect to T, given by ∂ISC/∂T.

- δ: Coefficient of variation of Pmax with respect to T, given by ∂Pmax/∂T.

Techniques for estimating these coefficients from experimental data can be found in the literature

Degradation
The ability of solar modules to withstand damage by rain, hail, heavy snow load, and cycles of heat and cold varies by manufacturer, although most solar panels on the U.S. market are UL listed, meaning they have gone through testing to withstand hail.

Potential-induced degradation (also called PID) is a potential-induced performance degradation in crystalline photovoltaic modules, caused by so-called stray currents. This effect may cause power loss of up to 30%.

The largest challenge for photovoltaic technology is the purchase price per watt of electricity produced. Advancements in photovoltaic technologies have brought about the process of "doping" the silicon substrate to lower the activation energy thereby making the panel more efficient in converting photons to retrievable electrons.

Chemicals such as boron (p-type) are applied into the semiconductor crystal in order to create donor and acceptor energy levels substantially closer to the valence and conductor bands. In doing so, the addition of boron impurity allows the activation energy to decrease twenty-fold from 1.12 eV to 0.05 eV. Since the potential difference (EB) is so low, the boron is able to thermally ionize at room temperatures. This allows for free energy carriers in the conduction and valence bands thereby allowing greater conversion of photons to electrons.

The power output of a photovoltaic (PV) device decreases over time. This decrease is due to its exposure to solar radiation as well as other external conditions. The degradation index, which is defined as the annual percentage of output power loss, is a key factor in determining the long-term production of a photovoltaic plant. To estimate this degradation, the percentage of decrease associated with each of the electrical parameters. The individual degradation of a photovoltaic module can significantly influence the performance of a complete string. Furthermore, not all modules in the same installation decrease their performance at exactly the same rate. Given a set of modules exposed to long-term outdoor conditions, the individual degradation of the main electrical parameters and the increase in their dispersion must be considered. As each module tends to degrade differently, the behavior of the modules will be increasingly different over time, negatively affecting the overall performance of the plant.

There are several studies dealing with the power degradation analysis of modules based on different photovoltaic technologies available in the literature. According to a recent study, the degradation of crystalline silicon modules is very regular, oscillating between 0.8% and 1.0% per year.

On the other hand, if we analyze the performance of thin-film photovoltaic modules, an initial period of strong degradation is observed (which can last several months and up to two years), followed by a later stage in which the degradation stabilizes, being then comparable to that of crystalline silicon. Strong seasonal variations are also observed in such thin-film technologies because the influence of the solar spectrum is much greater. For example, for modules of amorphous silicon, micromorphic silicon or cadmium telluride, we are talking about annual degradation rates for the first years of between 3% and 4%. However, other technologies, such as CIGS, show much lower degradation rates, even in those early years.

Manufacturing of PV systems
Overall the manufacturing process of creating solar photovoltaics is simple in that it does not require the culmination of many complex or moving parts. Because of the solid-state nature of PV systems, they often have relatively long lifetimes, anywhere from 10 to 30 years. To increase the electrical output of a PV system, the manufacturer must simply add more photovoltaic components. Because of this, economies of scale are important for manufacturers as costs decrease with increasing output.

While there are many types of PV systems known to be effective, crystalline silicon PV accounted for around 90% of the worldwide production of PV in 2013. Manufacturing silicon PV systems has several steps. First, polysilicon is processed from mined quartz until it is very pure (semi-conductor grade). This is melted down when small amounts of boron, a group III element, are added to make a p-type semiconductor rich in electron holes. Typically using a seed crystal, an ingot of this solution is grown from the liquid polycrystalline. The ingot may also be cast in a mold. Wafers of this semiconductor material are cut from the bulk material with wire saws, and then go through surface etching before being cleaned. Next, the wafers are placed into a phosphorus vapor deposition furnace which lays a very thin layer of phosphorus, a group V element, which creates an n-type semiconducting surface. To reduce energy losses, an anti-reflective coating is added to the surface, along with electrical contacts. After finishing the cell, cells are connected via electrical circuit according to the specific application and prepared for shipping and installation.

Environmental costs of manufacture
Solar photovoltaic power is not entirely "clean energy": production produces greenhouse gas emissions, materials used to build the cells are potentially unsustainable and will run out eventually, the technology uses toxic substances which cause pollution, and there are no viable technologies for recycling solar waste. Data required to investigate their impact are sometimes affected by a rather large amount of uncertainty. The values of human labor and water consumption, for example, are not precisely assessed due to the lack of systematic and accurate analyses in the scientific literature. One difficulty in determining effects due to PV is to determine if the wastes are released to the air, water, or soil during the manufacturing phase. Life-cycle assessments, which look at all different environment effects ranging from global warming potential, pollution, water depletion and others, are unavailable for PV. Instead, studies have tried to estimate the impact and potential impact of various types of PV, but these estimates are usually restricted to simply assessing energy costs of the manufacture and/or transport, because these are new technologies and the total environmental impact of their components and disposal methods are unknown, even for commercially available first generation solar cells, let alone experimental prototypes with no commercial viability.

Thus, estimates of the environmental impact of PV have focused on carbon dioxide equivalents per kWh or energy pay-back time (EPBT). The EPBT describes the timespan a PV system needs to operate in order to generate the same amount of energy that was used for its manufacture. Another study includes transport energy costs in the EPBT. The EPBT has also been defined completely differently as "the time needed to compensate for the total renewable- and non-renewable primary energy required during the life cycle of a PV system" in another study, which also included installation costs. This energy amortization, given in years, is also referred to as break-even energy payback time. The lower the EPBT, the lower the environmental cost of solar power. The EPBT depends vastly on the location where the PV system is installed (e.g. the amount of sunlight available and the efficiency of the electrical grid) and on the type of system, namely the system's components.

A 2015 review of EPBT estimates of first and second-generation PV suggested that there was greater variation in embedded energy than in efficiency of the cells implying that it was mainly the embedded energy that needs to reduce to have a greater reduction in EPBT.

In general, the most important component of solar panels, which accounts for much of the energy use and greenhouse gas emissions, is the refining of the polysilicon. As to how much percentage of the EPBT this silicon depends on the type of system. A fully autarkic system requires additional components ('Balance of System', the power inverters, storage, etc.) which significantly increase the energy cost of manufacture, but in a simple rooftop system, some 90% of the energy cost is from silicon, with the remainder coming from the inverters and module frame.

In an analysis by Alsema et al. from 1998, the energy payback time was higher than 10 years for the former system in 1997, while for a standard rooftop system the EPBT was calculated as between 3.5 and 8 years.

The EPBT relates closely to the concepts of net energy gain (NEG) and energy returned on energy invested (EROI). They are both used in energy economics and refer to the difference between the energy expended to harvest an energy source and the amount of energy gained from that harvest. The NEG and EROI also take the operating lifetime of a PV system into account and a working life of 25 to 30 years is typically assumed. From these metrics, the Energy payback Time can be derived by calculation.

EPBT improvements
PV systems using crystalline silicon, by far the majority of the systems in practical use, have such a high EPBT because silicon is produced by the reduction of high-grade quartz sand in electric furnaces. This coke-fired smelting process occurs at high temperatures of more than 1000 °C and is very energy intensive, using about 11 kilowatt-hours (kWh) per produced kilogram of silicon. The energy requirements of this process makes the energy cost per unit of silicon produced relatively inelastic, which means that the production process itself will not become more efficient in the future.

Nonetheless, the energy payback time has shortened significantly over the last years, as crystalline silicon cells became ever more efficient in converting sunlight, while the thickness of the wafer material was constantly reduced and therefore required less silicon for its manufacture. Within the last ten years, the amount of silicon used for solar cells declined from 16 to 6 grams per watt-peak. In the same period, the thickness of a c-Si wafer was reduced from 300 μm, or microns, to about 160–190 μm. The sawing techniques that slice crystalline silicon ingots into wafers have also improved by reducing the kerf loss and making it easier to recycle the silicon sawdust.

Effects from first generation PV
Crystalline silicon modules are the most extensively studied PV type in terms of LCA since they are the most commonly used. Mono-crystalline silicon photovoltaic systems (mono-si) have an average efficiency of 14.0%. The cells tend to follow a structure of front electrode, anti-reflection film, n-layer, p-layer, and back electrode, with the sun hitting the front electrode. EPBT ranges from 1.7 to 2.7 years. The cradle to gate of CO2-eq/kWh ranges from 37.3 to 72.2 grams when installed in Southern Europe.

Techniques to produce multi-crystalline silicon (multi-si) photovoltaic cells are simpler and cheaper than mono-si, however tend to make less efficient cells, an average of 13.2%. EPBT ranges from 1.5 to 2.6 years. The cradle to gate of CO2-eq/kWh ranges from 28.5 to 69 grams when installed in Southern Europe.

Assuming that the following countries had a high-quality grid infrastructure as in Europe, in 2020 it was calculated it would take 1.28 years in Ottawa, Canada, for a rooftop photovoltaic system to produce the same amount of energy as required to manufacture the silicon in the modules in it (excluding the silver, glass, mounts and other components), 0.97 years in Catania, Italy, and 0.4 years in Jaipur, India. Outside of Europe, where net grid efficiencies are lower, it would take longer. This 'energy payback time' can be seen as the portion of time during the useful lifetime of the module in which the energy production is polluting. At best, this means that a 30-year old panel has produced clean energy for 97% of its lifetime, or that the silicon in the modules in a solar panel produce 97% less greenhouse gas emissions than a coal-fired plant for the same amount of energy (assuming and ignoring many things). Some studies have looked beyond EPBT and GWP to other environmental effects. In one such study, conventional energy mix in Greece was compared to multi-si PV and found a 95% overall reduction in effects including carcinogens, eco-toxicity, acidification, eutrophication, and eleven others.

Impact from second generation PV
Cadmium telluride (CdTe) is one of the fastest-growing thin film based solar cells which are collectively known as second-generation devices. This new thin-film device also shares similar performance restrictions (Shockley-Queisser efficiency limit) as conventional Si devices but promises to lower the cost of each device by both reducing material and energy consumption during manufacturing. The global market share of CdTe was 4.7% in 2008. This technology's highest power conversion efficiency is 21%. The cell structure includes glass substrate (around 2 mm), transparent conductor layer, CdS buffer layer (50–150 nm), CdTe absorber and a metal contact layer.

CdTe PV systems require less energy input in their production than other commercial PV systems per unit electricity production. The average CO2-eq/kWh is around 18 grams (cradle to gate). CdTe has the fastest EPBT of all commercial PV technologies, which varies between 0.3 and 1.2 years.

Effects from third generation PV
Third-generation PVs are designed to combine the advantages of both the first and second generation devices and they do not have Shockley-Queisser limit, a theoretical limit for first and second generation PV cells. The thickness of a third generation device is less than 1 μm.

Two new promising thin film technologies are copper zinc tin sulfide (Cu2ZnSnS4 or CZTS), zinc phosphide (Zn3P2) and single-walled carbon nano-tubes (SWCNT). These thin films are currently only produced in the lab but may be commercialized in the future. The manufacturing of CZTS and (Zn3P2) processes are expected to be similar to those of current thin film technologies of CIGS and CdTe, respectively. While the absorber layer of SWCNT PV is expected to be synthesized with CoMoCAT method. by Contrary to established thin films such as CIGS and CdTe, CZTS, Zn3P2, and SWCNT PVs are made from earth abundant, nontoxic materials and have the potential to produce more electricity annually than the current worldwide consumption. While CZTS and Zn3P2 offer good promise for these reasons, the specific environmental implications of their commercial production are not yet known. Global warming potential of CZTS and Zn3P2 were found 38 and 30 grams CO2-eq/kWh while their corresponding EPBT were found 1.85 and 0.78 years, respectively. Overall, CdTe and Zn3P2 have similar environmental effects but can slightly outperform CIGS and CZTS. A study on environmental impacts of SWCNT PVs by Celik et al., including an existing 1% efficient device and a theoretical 28% efficient device, found that, compared to monocrystalline Si, the environmental impacts from 1% SWCNT was ~18 times higher due mainly to the short lifetime of three years.

Economics
There have been major changes in the underlying costs, industry structure and market prices of solar photovoltaics technology, over the years, and gaining a coherent picture of the shifts occurring across the industry value chain globally is a challenge. This is due to: "the rapidity of cost and price changes, the complexity of the PV supply chain, which involves a large number of manufacturing processes, the balance of system (BOS) and installation costs associated with complete PV systems, the choice of different distribution channels, and differences between regional markets within which PV is being deployed". Further complexities result from the many different policy support initiatives that have been put in place to facilitate photovoltaics commercialisation in various countries.

Renewable energy technologies have generally gotten cheaper since their invention. Renewable energy systems have become cheaper to build than fossil fuel power plants across much of the world, thanks to advances in wind and solar energy technology, in particular.

Hardware costs
In 1977 crystalline silicon solar cell prices were at $76.67/W.

Although wholesale module prices remained flat at around $3.50 to $4.00/W in the early 2000s due to high demand in Germany and Spain afforded by generous subsidies and shortage of polysilicon, demand crashed with the abrupt ending of Spanish subsidies after the market crash of 2008, and the price dropped rapidly to $2.00/W. Manufacturers were able to maintain a positive operating margin despite a 50% drop in income due to innovation and reductions in costs. In late 2011, factory-gate prices for crystalline-silicon photovoltaic modules suddenly dropped below the $1.00/W mark, taking many in the industry by surprise, and has caused a number of solar manufacturing companies to go bankrupt throughout the world. The $1.00/W cost is often regarded in the PV industry as marking the achievement of grid parity for PV, but most experts do not believe this price point is sustainable. Technological advancements, manufacturing process improvements, and industry re-structuring, may mean that further price reductions are possible. The average retail price of solar cells as monitored by the Solarbuzz group fell from $3.50/watt to $2.43/watt over the course of 2011. In 2013 wholesale prices had fallen to $0.74/W. This has been cited as evidence supporting 'Swanson's law', an observation similar to the famous Moore's Law, which claims that solar cell prices fall 20% for every doubling of industry capacity. The Fraunhofer Institute defines the 'learning rate' as the drop in prices as the cumulative production doubles, some 25% between 1980 and 2010. Although the prices for modules have dropped quickly, current inverter prices have dropped at a much lower rate, and in 2019 constitute over 61% of the cost per kWp, from a quarter in the early 2000s.

Note that the prices mentioned above are for bare modules, another way of looking at module prices is to include installation costs. In the US, according to the Solar Energy Industries Association, the price of installed rooftop PV modules for homeowners fell from $9.00/W in 2006 to $5.46/W in 2011. Including the prices paid by industrial installations, the national installed price drops to $3.45/W. This is markedly higher than elsewhere in the world, in Germany homeowner rooftop installations averaged at $2.24/W. The cost differences are thought to be primarily based on the higher regulatory burden and lack of a national solar policy in the US.

By the end of 2012 Chinese manufacturers had production costs of $0.50/W in the cheapest modules. In some markets distributors of these modules can earn a considerable margin, buying at factory-gate price and selling at the highest price the market can support ('value-based pricing'). In California PV reached grid parity in 2011, which is usually defined as PV production costs at or below retail electricity prices (though often still above the power station prices for coal or gas-fired generation without their distribution and other costs). Grid parity had been reached in 19 markets in 2014.

By 2024, massive increases of production of solar panels in China had caused module prices to drop to as low as $0.11/W, an over 90 percent reduction from 2011 prices.

Levelised cost of electricity
The levelised cost of electricity (LCOE) is the cost per kWh based on the costs distributed over the project lifetime, and is thought to be a better metric for calculating viability than price per wattage. LCOEs vary dramatically depending on the location. The LCOE can be considered the minimum price customers will have to pay the utility company in order for it to break even on the investment in a new power station. Grid parity is roughly achieved when the LCOE falls to a similar price as conventional local grid prices, although in actuality the calculations are not directly comparable. Large industrial PV installations had reached grid parity in California in 2011. Grid parity for rooftop systems was still believed to be much farther away at this time. Many LCOE calculations are not thought to be accurate, and a large amount of assumptions are required. Module prices may drop further, and the LCOE for solar may correspondingly drop in the future.

Because energy demands rise and fall over the course of the day, and solar power is limited by the fact that the sun sets, solar power companies must also factor in the additional costs of supplying a more stable alternative energy supplies to the grid in order to stabilize the system, or storing the energy somehow (current battery technology cannot store enough power). These costs are not factored into LCOE calculations, nor are special subsidies or premiums that may make buying solar power more attractive. The unreliability and temporal variation in generation of solar and wind power is a major problem. Too much of these volatile power sources can cause instability of the entire grid.

As of 2017 power-purchase agreement prices for solar farms below $0.05/kWh are common in the United States, and the lowest bids in some Persian Gulf countries were about $0.03/kWh. The goal of the United States Department of Energy is to achieve a levelised cost of energy for solar PV of $0.03/kWh for utility companies.

Subsidies and financing
Financial incentives for photovoltaics, such as feed-in tariffs (FITs), have often been offered to electricity consumers to install and operate solar-electric generating systems, and in some countries such subsidies are the only way photovoltaics can remain economically profitable. In Germany FIT subsidies are generally around €0.13 above the normal retail price of a kWh (€0.05). PV FITs have been crucial for the adoption of the industry, and are available to consumers in over 50 countries as of 2011. Germany and Spain have been the most important countries regarding offering subsidies for PV, and the policies of these countries have driven demand in the past. Some US solar cell manufacturing companies have repeatedly complained that the dropping prices of PV module costs have been achieved due to subsidies by the government of China, and the dumping of these products below fair market prices. US manufacturers generally recommend high tariffs on foreign supplies to allow them remain profitable. In response to these concerns, the Obama administration began to levy tariffs on US consumers of these products in 2012 to raise prices for domestic manufacturers. The USA, however, also subsidies the industry, offering consumers a 30% federal tax credit to purchase modules. In Hawaii federal and state subsidies chop off up to two thirds of the installation costs.

Some environmentalists have promoted the idea that government incentives should be used in order to expand the PV manufacturing industry to reduce costs of PV-generated electricity much more rapidly to a level where it is able to compete with fossil fuels in a free market. This is based on the theory that when the manufacturing capacity doubles, economies of scale will cause the prices of the solar products to halve.

In many countries there is access to capital is lacking to develop PV projects. To solve this problem, securitization has been proposed to accelerate development of solar photovoltaic projects. For example, SolarCity offered the first U.S. asset-backed security in the solar industry in 2013.

Other
Photovoltaic power is also generated during a time of day that is close to peak demand (precedes it) in electricity systems with high use of air conditioning. Since large-scale PV operation requires back-up in the form of spinning reserves, its marginal cost of generation in the middle of the day is typically lowest, but not zero, when PV is generating electricity. This can be seen in Figure 1 of this paper:. For residential properties with private PV facilities networked to the grid, the owner may be able earn extra money when the time of generation is included, as electricity is worth more during the day than at night.

One journalist theorised in 2012 that if the energy bills of Americans were forced upwards by imposing an extra tax of $50/ton on carbon dioxide emissions from coal-fired power, this could have allowed solar PV to appear more cost-competitive to consumers in most locations.

Growth

Solar photovoltaics formed the largest body of research among the seven sustainable energy types examined in a global bibliometric study, with the annual scientific output growing from 9,094 publications in 2011 to 14,447 publications in 2019.

Likewise, the application of solar photovoltaics is growing rapidly and the worldwide installed capacity reached one terawatt in April 2022. The total power output of the world's PV capacity in a calendar year is now beyond 500 TWh of electricity. This represents 2% of worldwide electricity demand. More than 100 countries, such as Brazil and India, use solar PV. China is followed by the United States and Japan, while installations in Germany, once the world's largest producer, have been slowing down.

Honduras generated the highest percentage of its energy from solar in 2019, 14.8%. As of 2019, Vietnam has the highest installed capacity in Southeast Asia, about 4.5 GW. The annualized installation rate of about 90 W per capita per annum places Vietnam among world leaders. Generous Feed-in tariff (FIT) and government supporting policies such as tax exemptions were the key to enable Vietnam's solar PV boom. Underlying drivers include the government's desire to enhance energy self-sufficiency and the public's demand for local environmental quality.

A key barrier is limited transmission grid capacity.

China has the world's largest solar power capacity, with 390 GW of installed capacity in 2022 compared with about 200 GW in the European Union, according to International Energy Agency data. Other countries with the world's largest solar power capacities include the United States, Japan and Germany.

In 2017, it was thought probable that by 2030 global PV installed capacities could be between 3,000 and 10,000 GW. Greenpeace in 2010 claimed that 1,845 GW of PV systems worldwide could be generating approximately 2,646 TWh/year of electricity by 2030, and by 2050 over 20% of all electricity could be provided by PV.

Applications
There are many practical applications for the use of solar panels or photovoltaics covering every technological domain under the sun. From the fields of the agricultural industry as a power source for irrigation to its usage in remote health care facilities to refrigerate medical supplies. Other applications include power generation at various scales and attempts to integrate them into homes and public infrastructure. PV modules are used in photovoltaic systems and include a large variety of electrical devices.

Photovoltaic systems
A photovoltaic system, or solar PV system is a power system designed to supply usable solar power by means of photovoltaics. It consists of an arrangement of several components, including solar panels to absorb and directly convert sunlight into electricity, a solar inverter to change the electric current from DC to AC, as well as mounting, cabling and other electrical accessories. PV systems range from small, roof-top mounted or building-integrated systems with capacities from a few to several tens of kilowatts, to large utility-scale power stations of hundreds of megawatts. Nowadays, most PV systems are grid-connected, while stand-alone systems only account for a small portion of the market.

Photo sensors
Photosensors are sensors of light or other electromagnetic radiation. A photo detector has a p–n junction that converts light photons into current. The absorbed photons make electron–hole pairs in the depletion region. Photodiodes and photo transistors are a few examples of photo detectors. Solar cells convert some of the light energy absorbed into electrical energy.

Experimental technology
Crystalline silicon photovoltaics are only one type of PV, and while they represent the majority of solar cells produced currently there are many new and promising technologies that have the potential to be scaled up to meet future energy needs. As of 2018, crystalline silicon cell technology serves as the basis for several PV module types, including monocrystalline, multicrystalline, mono PERC, and bifacial.

Another newer technology, thin-film PV, are manufactured by depositing semiconducting layers of perovskite, a mineral with semiconductor properties, on a substrate in vacuum. The substrate is often glass or stainless-steel, and these semiconducting layers are made of many types of materials including cadmium telluride (CdTe), copper indium diselenide (CIS), copper indium gallium diselenide (CIGS), and amorphous silicon (a-Si). After being deposited onto the substrate the semiconducting layers are separated and connected by electrical circuit by laser scribing. Perovskite solar cells are a very efficient solar energy converter and have excellent optoelectronic properties for photovoltaic purposes, but their upscaling from lab-sized cells to large-area modules is still under research. Thin-film photovoltaic materials may possibly become attractive in the future, because of the reduced materials requirements and cost to manufacture modules consisting of thin-films as compared to silicon-based wafers. In 2019 university labs at Oxford, Stanford and elsewhere reported perovskite solar cells with efficiencies of 20-25%.

CIGS
Copper indium gallium selenide (CIGS) is a thin film solar cell based on the copper indium diselenide (CIS) family of chalcopyrite semiconductors. CIS and CIGS are often used interchangeably within the CIS/CIGS community. The cell structure includes soda lime glass as the substrate, Mo layer as the back contact, CIS/CIGS as the absorber layer, cadmium sulfide (CdS) or Zn (S,OH)x as the buffer layer, and ZnO:Al as the front contact. CIGS is approximately 1/100th the thickness of conventional silicon solar cell technologies. Materials necessary for assembly are readily available, and are less costly per watt of solar cell. CIGS based solar devices resist performance degradation over time and are highly stable in the field.

Reported global warming potential impacts of CIGS ranges 20.5–58.8 grams CO2-eq/kWh of electricity generated for different solar irradiation (1,700 to 2,200 kWh/m2/y) and power conversion efficiency (7.8 – 9.12%). EPBT ranges from 0.2 to 1.4 years, while harmonized value of EPBT was found 1.393 years. Toxicity is an issue within the buffer layer of CIGS modules because it contains cadmium and gallium. CIS modules do not contain any heavy metals.

Dye-Sensitized Solar Cells
Dye-sensitized solar cells (DSCs) are a novel thin film solar cell. These solar cells operate under ambient light better than other photovoltaic technologies. They work with light being absorbed in a sensitizing dye between two charge transport materials. Dye surrounds TiO2 nanoparticles which are in a sintered network. TiO2 acts as conduction band in an n-type semiconductor; the scaffold for adorned dye molecules and transports elections during excitation. For TiO2 DSC technology, sample preparation at high temperatures is very effective because higher temperatures produce more suitable textural properties. Another example of DSCs is the copper complex with Cu (II/I) as a redox shuttle with TMBY (4,4',6,6'-tetramethyl-2,2'bipyridine). DSCs show great performance with artificial and indoor light. From a range of 200 lux to 2,000 lux, these cells operate at conditions of a maximum efficiency of 29.7%.

However, there have been issues with DSCs, many of which come from the liquid electrolyte. The solvent is hazardous, and will permeate most plastics. Because it is liquid, it is unstable to temperature variation, leading to freezing in cold temperatures and expansion in warm temperatures causing failure. Another disadvantage is that the solar cell is not ideal for large scale application because of its low efficiency. Some of the benefits for DSC is that it can be used in a variety of light levels (including cloudy conditions), it has a low production cost, and it does not degrade under sunlight, giving it a longer lifetime then other types of thin film solar cells.

OPV
Other possible future PV technologies include organic, dye-sensitized and quantum-dot photovoltaics. Organic photovoltaics (OPVs) fall into the thin-film category of manufacturing, and typically operate around the 12% efficiency range which is lower than the 12–21% typically seen by silicon-based PVs. Because organic photovoltaics require very high purity and are relatively reactive they must be encapsulated which vastly increases the cost of manufacturing and means that they are not feasible for large scale-up. Dye-sensitized PVs are similar in efficiency to OPVs but are significantly easier to manufacture. However, these dye-sensitized photovoltaics present storage problems because the liquid electrolyte is toxic and can potentially permeate the plastics used in the cell. Quantum dot solar cells are solution-processed, meaning they are potentially scalable, but currently they peak at 12% efficiency.

Organic and polymer photovoltaic (OPV) are a relatively new area of research. The tradition OPV cell structure layers consist of a semi-transparent electrode, electron blocking layer, tunnel junction, holes blocking layer, electrode, with the sun hitting the transparent electrode. OPV replaces silver with carbon as an electrode material lowering manufacturing cost and making them more environmentally friendly. OPV are flexible, low weight, and work well with roll-to roll manufacturing for mass production. OPV uses "only abundant elements coupled to an extremely low embodied energy through very low processing temperatures using only ambient processing conditions on simple printing equipment enabling energy pay-back times". Current efficiencies range 1–6.5%, however theoretical analyses show promise beyond 10% efficiency.

Many different configurations of OPV exist using different materials for each layer. OPV technology rivals existing PV technologies in terms of EPBT even if they currently present a shorter operational lifetime. A 2013 study analyzed 12 different configurations all with 2% efficiency, the EPBT ranged from 0.29 to 0.52 years for 1 m2 of PV. The average CO2-eq/kWh for OPV is 54.922 grams.

Solar module alignment
A number of solar modules may also be mounted vertically above each other in a tower, if the zenith distance of the Sun is greater than zero, and the tower can be turned horizontally as a whole and each module additionally around a horizontal axis. In such a tower the modules can follow the Sun exactly. Such a device may be described as a ladder mounted on a turnable disk. Each step of that ladder is the middle axis of a rectangular solar panel. In case the zenith distance of the Sun reaches zero, the "ladder" may be rotated to the north or the south to avoid a solar module producing a shadow on a lower one. Instead of an exactly vertical tower one can choose a tower with an axis directed to the polar star, meaning that it is parallel to the rotation axis of the Earth. In this case the angle between the axis and the Sun is always larger than 66 degrees. During a day it is only necessary to turn the panels around this axis to follow the Sun. Installations may be ground-mounted (and sometimes integrated with farming and grazing) or built into the roof or walls of a building (building-integrated photovoltaics).

Where land may be limited, PV can be deployed as floating solar. In 2008 the Far Niente Winery pioneered the world's first "floatovoltaic" system by installing 994 photovoltaic solar panels onto 130 pontoons and floating them on the winery's irrigation pond. A benefit of the set up is that the panels are kept at a lower temperature than they would be on land, leading to a higher efficiency of solar energy conversion. The floating panels also reduce the amount of water lost through evaporation and inhibit the growth of algae.

Concentrator photovoltaics is a technology that contrary to conventional flat-plate PV systems uses lenses and curved mirrors to focus sunlight onto small, but highly efficient, multi-junction solar cells. These systems sometimes use solar trackers and a cooling system to increase their efficiency.

Efficiency
In 2019, the world record for solar cell efficiency at 47.1% was achieved by using multi-junction concentrator solar cells, developed at National Renewable Energy Laboratory, Colorado, US. The highest efficiencies achieved without concentration include a material by Sharp Corporation at 35.8% using a proprietary triple-junction manufacturing technology in 2009, and Boeing Spectrolab (40.7% also using a triple-layer design).

There is an ongoing effort to increase the conversion efficiency of PV cells and modules, primarily for competitive advantage. In order to increase the efficiency of solar cells, it is important to choose a semiconductor material with an appropriate band gap that matches the solar spectrum. This will enhance the electrical and optical properties. Improving the method of charge collection is also useful for increasing the efficiency. There are several groups of materials that are being developed. Ultrahigh-efficiency devices (η>30%) are made by using GaAs and GaInP2 semiconductors with multijunction tandem cells. High-quality, single-crystal silicon materials are used to achieve high-efficiency, low cost cells (η>20%).

Recent developments in organic photovoltaic cells (OPVs) have made significant advancements in power conversion efficiency from 3% to over 15% since their introduction in the 1980s. To date, the highest reported power conversion efficiency ranges 6.7–8.94% for small molecule, 8.4–10.6% for polymer OPVs, and 7–21% for perovskite OPVs. OPVs are expected to play a major role in the PV market. Recent improvements have increased the efficiency and lowered cost, while remaining environmentally-benign and renewable.

Several companies have begun embedding power optimizers into PV modules called smart modules. These modules perform maximum power point tracking (MPPT) for each module individually, measure performance data for monitoring, and provide additional safety features. Such modules can also compensate for shading effects, wherein a shadow falling across a section of a module causes the electrical output of one or more strings of cells in the module to decrease.

One of the major causes for the decreased performance of cells is overheating. The efficiency of a solar cell declines by about 0.5% for every 1 degree Celsius increase in temperature. This means that a 100 degree increase in surface temperature could decrease the efficiency of a solar cell by about half. Self-cooling solar cells are one solution to this problem. Rather than using energy to cool the surface, pyramid and cone shapes can be formed from silica, and attached to the surface of a solar panel. Doing so allows visible light to reach the solar cells, but reflects infrared rays (which carry heat).

Advantages

 * Pollution and energy in production

The 122 PW of sunlight reaching the Earth's surface is plentiful—almost 10,000 times more than the 13 TW equivalent of average power consumed in 2005 by humans. This abundance leads to the suggestion that it will not be long before solar energy will become the world's primary energy source. Additionally, solar radiation has the highest power density (global mean of 170 W/m2) among renewable energies.

Solar power is pollution-free during use, which enables it to cut down on pollution when it is substituted for other energy sources. For example, MIT estimated that 52,000 people per year die prematurely in the U.S. from coal-fired power plant pollution and all but one of these deaths could be prevented from using PV to replace coal. Production end-wastes and emissions are manageable using existing pollution controls. End-of-use recycling technologies are under development and policies are being produced that encourage recycling from producers.

PV installations could ideally operate for 100 years or even more with little maintenance or intervention after their initial set-up, so after the initial capital cost of building any solar power plant, operating costs are extremely low compared to existing power technologies.

Grid-connected solar electricity can be used locally thus reducing transmission/distribution losses (transmission losses in the US were approximately 7.2% in 1995).

 * Solar cell research investment

Compared to fossil and nuclear energy sources, very little research money has been invested in the development of solar cells, so there is considerable room for improvement. Nevertheless, experimental high efficiency solar cells already have efficiencies of over 40% in case of concentrating photovoltaic cells and efficiencies are rapidly rising while mass-production costs are rapidly falling.

 * Housing subsidies

In some states of the United States, much of the investment in a home-mounted system may be lost if the homeowner moves and the buyer puts less value on the system than the seller. The city of Berkeley developed an innovative financing method to remove this limitation, by adding a tax assessment that is transferred with the home to pay for the solar panels. Now known as PACE, Property Assessed Clean Energy, 30 U.S. states have duplicated this solution.

Disadvantages
For behind-the-meter rooftop photovoltaic systems, the energy flow becomes two-way. When there is more local generation than consumption, electricity is exported to the grid, allowing for net metering. However, electricity networks traditionally are not designed to deal with two-way energy transfer, which may introduce technical issues. An over-voltage issue may come out as the electricity flows from these PV households back to the network. There are solutions to manage the over-voltage issue, such as regulating PV inverter power factor, new voltage and energy control equipment at electricity distributor level, re-conductor the electricity wires, demand side management, etc. There are often limitations and costs related to these solutions.
 * Impact on electricity network

High generation during the middle of the day reduces the net generation demand, but higher peak net demand as the sun goes down can require rapid ramping of utility generating stations, producing a load profile called the duck curve.

 * Implications for electricity bill management and energy investment

There is no silver bullet in electricity or energy demand and bill management, because customers (sites) have different specific situations, e.g. different comfort/convenience needs, different electricity tariffs, or different usage patterns. Electricity tariff may have a few elements, such as daily access and metering charge, energy charge (based on kWh, MWh) or peak demand charge (e.g. a price for the highest 30min energy consumption in a month). PV is a promising option for reducing energy charges when electricity prices are reasonably high and continuously increasing, such as in Australia and Germany. However, for sites with peak demand charge in place, PV may be less attractive if peak demands mostly occur in the late afternoon to early evening, for example in residential communities. Overall, energy investment is largely an economic decision and it is better to make investment decisions based on systematic evaluation of options in operational improvement, energy efficiency, onsite generation and energy storage.

title: Photovoltaics


text:
Despotate of Epirus

The Despotate of Epirus (Δεσποτᾶτον τῆς Ἠπείρου) was one of the Greek successor states of the Byzantine Empire established in the aftermath of the Fourth Crusade in 1204 by a branch of the Angelos dynasty. It claimed to be the legitimate successor of the Byzantine Empire, along with the Empire of Nicaea and the Empire of Trebizond, its rulers briefly proclaiming themselves as Emperors in 1227–1242 (during which it is most often called the Empire of Thessalonica). The term "Despotate of Epirus" is, like "Byzantine Empire" itself, a modern historiographic convention and not a name in use at the time.

The Despotate was centred on the region of Epirus, encompassing also Albania and the western portion of Greek Macedonia and also included Thessaly and western Greece as far south as Nafpaktos. Through a policy of aggressive expansion under Theodore Komnenos Doukas the Despotate of Epirus also briefly came to incorporate central Macedonia, with the establishment of the Empire of Thessalonica in 1224, and Thrace as far east as Didymoteicho and Adrianople, and was on the verge of recapturing Constantinople and restoring the Byzantine Empire before the Battle of Klokotnitsa in 1230 where he was defeated by the Bulgarian Empire. After that, the Epirote state contracted to its core in Epirus and Thessaly, and was forced into vassalage to other regional powers. It nevertheless managed to retain its autonomy until being conquered by the restored Palaiologan Byzantine Empire in ca. 1337. In the 1410s, the Count palatine of Cephalonia and Zakynthos Carlo I Tocco managed to reunite the core of the Epirote state, but his successors gradually lost it to the advancing Ottoman Empire, with the last stronghold, Vonitsa, falling to the Ottomans in 1479.

Nomenclature
In traditional and modern historiography, the Epirote state is usually termed the "Despotate of Epirus" and its rulers are summarily attributed the title of "Despot" from its inception, but this use is not strictly accurate. First of all, the title of "Despot" was not borne by all Epirote rulers: the state's founder, Michael I Komnenos Doukas, never used it, and is only anachronistically referred to as "Despot of Epirus" in 14th-century Western European sources. His successor Theodore Komnenos Doukas did not use it either, and actually crowned himself emperor (basileus) at Thessalonica c. 1225. The first ruler of Epirus to receive the title of Despot was Michael II, from his uncle Manuel of Thessalonica in the 1230s, and then again, as a sign of submission and vassalage, from the Nicaean emperor John III Vatatzes. Earlier historians assumed that Michael I was indeed named "Despot" by the deposed emperor Alexios III Angelos after ransoming him from Latin captivity in c. 1206/7 or c. 1210; this has been disproven by more recent research.

Furthermore, even after Michael II, speaking of the Epirote rulers as "Despots of Epirus" is technically incorrect. The title of Despot did not imply any specific territorial jurisdiction, nor was it hereditary; it was merely the highest rank in the Byzantine court hierarchy, awarded by a reigning emperor to close relatives, usually his sons. Consequently, it was often borne by the princes sent to govern semi-autonomous appanages and only later came to be associated with these territories as the practice became regularized (aside from Epirus, the Despotate of the Morea is the most notable case). The territorial term "despotate" itself (in Greek δεσποτᾶτον, despotaton) was first used in contemporary sources for Epirus only from the 14th century on, e.g. in the Chronicle of the Morea, in the history of John Kantakouzenos, the hagiography of St. Niphon, or the Chronicle of the Tocco, where the inhabitants of the Despotate are referred to as the Despotatoi. The term "Despotate of Epirus" is thus sometimes replaced by "(Independent) State of Epirus" in more recent historiography.

The Epirote realm itself did not have an official name. Contemporaries, particularly in Western Europe, used the term Romania, which generally referred to the whole Byzantine Empire, to refer specifically to Epirus, as seen in the Latin title of Despotus Romanie claimed by Philip I of Taranto and his son Philip of Apulia, Nicholas Orsini, and later Carlo I Tocco. In the Byzantine world, the term Dysis (Δύσις), meaning "West", which historically referred to Dalmatia, Macedonia and Sicily, or even the entire European part of the Empire, also came into use already in the 13th century when juxtaposing Epirus to its eastern rival, the Empire of Nicaea, which was then called Anatolē (Ἀνατολή), "East". Moreover, the term "Hellenes" was widely used instead of the earlier "Romans" by the 13th-century court of the Despotate to describe its population.

Foundation
The Epirote state was founded in 1205 by Michael Komnenos Doukas, a cousin of the Byzantine emperors Isaac II Angelos and Alexios III Angelos. At first, Michael allied with Boniface of Montferrat, but having lost the Morea (Peloponnese) to the Franks at the battle of the Olive Grove of Koundouros, he went to Epirus, where he considered himself the Byzantine governor of the old province of Nicopolis and revolted against Boniface. Epirus soon became the new home of many refugees from Constantinople, Thessaly, and the Peloponnese, and Michael was described as a second Noah, rescuing men from the Latin flood. John X Kamateros, the Patriarch of Constantinople, did not consider him a legitimate successor and instead joined Theodore I Laskaris in Nicaea; Michael instead recognized the authority of Pope Innocent III over Epirus, cutting ties to the Eastern Orthodox Church.

Henry of Flanders demanded that Michael submit to the Latin Empire, which he did, at least nominally, by allowing his daughter to marry Henry's brother Eustace in 1209. Michael did not honour this alliance, assuming that mountainous Epirus would be mostly impenetrable by any Latins with whom he made and broke alliances. Meanwhile, Boniface's relatives from Montferrat made claims to Epirus as well, and in 1210 Michael allied with the Venetians and attacked Boniface's Kingdom of Thessalonica. Pope Innocent III excommunicated him in response. Henry forced Michael into a renewed nominal alliance later that year.

Michael turned his attention to capturing other strategically important Latin-held towns, including Larissa and Dyrrhachium. He also took control of the ports on the Gulf of Corinth. In 1214 he captured Corcyra from Venice, but he was assassinated later that year and was succeeded by his half-brother Theodore.

Conflict with Nicaea and Bulgaria

Theodore Komnenos Doukas immediately set out to attack Thessalonica, and he fought with the Bulgarians along the way. Henry of Flanders died on the way to counterattack, and in 1217 Theodore captured his successor Peter of Courtenay, most likely executing him. The Latin Empire, however, became distracted by the growing power of Nicaea and could not stop Theodore from capturing Thessalonica in 1224. Theodore now challenged Nicaea for the imperial title and crowned himself emperor, founding the short-lived Empire of Thessalonica. In 1225, after John III Doukas Vatatzes of Nicaea had taken Adrianople, Theodore arrived and took it back from him. Theodore also allied with the Bulgarians and drove the Latins out of Thrace. In 1227 Theodore crowned himself Byzantine emperor, although this was not recognized by most Greeks, especially not the Patriarch in Nicaea.

In 1230 Theodore broke the truce with Bulgaria, hoping to remove Ivan Asen II, who had held him back from attacking Constantinople. In the battle of Klokotnitsa (near Haskovo in Bulgaria) the Bulgarian emperor defeated Theodore, capturing and later blinding him. His brother Manuel Komnenos Doukas took power in Thessalonica, but Epirus itself soon broke away under Michael I's illegitimate son, Michael II Komnenos Doukas. Manuel awarded Michael the title of Despot—making Michael the first Epirote ruler to bear the title—as a sign of his nominal dependency on Thessalonica, but Michael was de facto independent, which he demonstrated by seizing Corfu in ca. 1236. In the rump Empire of Thessalonica, after Theodore was released in 1237, he overthrew his brother Manuel, and set up his son John Komnenos Doukas as ruler of Thessalonica.

Nicaean and Byzantine suzerainty

Thessalonica never regained its power after the battle of Klokotnitsa. Theodore's younger son Demetrios Angelos Doukas lost Thessalonica to Nicaea in 1246 and Michael II of Epirus allied with the Latins against the Nicaeans. In 1248 John III Doukas Vatatzes of Nicaea forced Michael to recognize him as emperor, and officially recognized him in turn as despotēs in Epirus. Vatatzes' granddaughter Maria later (in 1256) married Michael's son Nikephoros, although she died in 1258. Also in 1248 Michael's daughter Anna married William II, Prince of Achaea, and Michael decided to honour this alliance over his obligations to Vatatzes. The allies were defeated in the ensuing conflict at the Battle of Pelagonia in 1259.

Emperor Theodore II Laskaris allied with Michael II, and their children, betrothed by John years before, finally married in 1256, with Theodore receiving Dyrrhachium in return. Michael did not accept this transfer of land, and in 1257 he revolted, defeating a Nicaean army led by George Acropolites. As Michael marched on Thessalonica, he was attacked by King Manfred of Sicily, who conquered Albania and Corcyra. However, Michael immediately allied with him by marrying his daughter Helena to him. After Theodore II died, Michael, Manuel, and William II fought the new Nicaean emperor, Michael VIII Palaiologos. The alliance was very unstable and in 1259 William was captured at the disastrous Battle of Pelagonia. Michael VIII went on to capture Michael II's capital of Arta, leaving Epirus with only Ioannina and Vonitsa. Arta was recovered by 1260 while Michael VIII was occupied against Constantinople.

Italian invasions
After Michael VIII restored the empire in Constantinople in 1261 he frequently harassed Epirus, and forced Michael's son Nikephoros to marry his niece Anna Palaiologina Kantakouzene in 1265. Michael considered Epirus a vassal state, although Michael II and Nikephoros continued to ally with the Princes of Achaea and the Dukes of Athens. In 1267 Corcyra and much of Epirus were taken by Charles of Anjou, and in 1267/68 Michael II died. Michael VIII did not attempt to annex Epirus directly, and allowed Nikephoros I to succeed his father and deal with Charles, who captured Dyrrhachium in 1271. In 1279 Nikephoros allied with Charles against Michael VIII, agreeing to become Charles' vassal. With Charles' defeat soon after Nikephoros lost Albania to the Byzantines.

Under Andronikos II Palaiologos, son of Michael VIII, Nikephoros renewed the alliance with Constantinople. Nikephoros, however, was persuaded to ally with Charles II of Naples in 1292, although Charles was defeated by Andronikos's fleet. Nikephoros married his daughter to Charles's son Philip I of Taranto and sold much of his territory to him. After Nikephoros's death in c. 1297 Byzantine influence grew under his widow Anna, Andronikos's cousin, who ruled as regent for her young son Thomas I Komnenos Doukas. In 1306 she revolted against Philip in favour of Andronikos; the Latin inhabitants were expelled but she was forced to return some territory to Philip. In 1312 Philip abandoned his claim to Epirus and claimed the defunct Latin Empire of Constantinople instead as the inheritance of his wife Catherine II of Valois, Princess of Achaea.

Collapse of the despotate

Anna succeeded in marrying off Thomas to a daughter of Michael IX, but Thomas was assassinated in 1318 by his cousin Nicholas Orsini, who married his widow and claimed to rule not only Epirus, but all of Greece; his rule was limited only to Akamania, or the southern part of Epirus. He was overthrown by his brother John in 1323, who attempted to balance submission to Constantinople with cooperation with the Angevins of Naples, who also claimed Greece as part of their domains. John was poisoned around 1335 by his wife Anna, who became regent for their son Nikephoros II. In 1337 the new Emperor, Andronikos III Palaiologos, arrived in northern Epirus with an army partly composed of 2,000 Turks contributed by his ally Umur of Aydın. Andronikos first dealt with unrest due to attacks by Albanians and then turned his interest to the Despotate. Anna tried to negotiate and obtain the Despotate for her son when he came of age, but Andronikos demanded the complete surrender of the Despotate to which she finally agreed. Thus Epirus came peacefully under imperial rule, with Theodore Synadenos as governor.

The imperials had insisted that Nikephoros would be engaged to one of the daughters of the emperor's right-hand man, John Kantakouzenos. When the time of the engagement came, Nikephoros had vanished. Andronikos learned that Nikephoros had fled to Italy, with the help of members of the Epirote aristocracy who supported an independent Epirus. He stayed in Taranto, Italy, in the court of Catherine II of Valois (Philip of Taranto's widow), the titular empress of Constantinople.

In 1339 a revolt began, supported by Catherine of Valois, who had previously moved to the Peloponnese, and by Nikephoros who had returned to Epirus, based in Thomokastron. By the end of the year the imperial army returned to the area, and in the following year, 1340, Andronikos III himself arrived together with John Kantakouzenos. Nikephoros was persuaded through diplomacy to recognize the authority of the emperor. He surrendered Thomokastron, married Maria Kantakouzene, the daughter of John Kantakouzenos, and received the title of panhypersebastos.

The Empire soon fell into a civil war between John V Palaiologos and John VI Kantakouzenos, and Epirus was conquered by the Serbian tsar Stefan Dušan in 1348, who appointed his brother, despot Simeon Nemanjić-Palailogos as governor of the province. Nikephoros II took advantage of the Byzantine civil war and the death of Dušan (1355) to escape and to reestablish himself in Epirus in 1356, to which he also added Thessaly. Nikephoros was killed in battle putting down an Albanian revolt in 1359, and the territory of the former despotate became a component part of the personal Empire of Dušan's brother Simeon Nemanjić-Palailogos. Simeon was also governing Thessaly at the time, and, as the Chronicle of Ioannina shows, he left much of the territory under the control of Albanian clans establishing short-lived entities: the clan of Pjetër Losha held Arta, and the clan of Muriq Shpata held Aetoloacarnania, with Angelokastron as its capital.

In 1367 a part of the Epirotan Despotate was resurrected under local Serbian nobleman Thomas II Preljubović, who kept Ioannina. After Thomas' death in 1384, his widow remarried in 1385 and transferred the Despotate to homage of Italian nobility. The state tradition was carried on by the Serbian and Italian rulers of Ioannina, who solicited aid from the Ottoman Turks against the Albanians. In 1399 the Albanian leader of Principality of Gjirokastër, Gjon Zenebishi captured the Despot Esau de' Buondelmonti and released him after 15 months, when his relatives in Italy offered a huge amount of money as a ransom. By 1416 the Tocco family of Cephalonia succeeded in reuniting Epirus, or at least in asserting their control over its towns. But internal dissension eased the Ottoman conquest, which proceeded with the capture of Ioannina in 1430, Arta in 1449, Angelokastron in 1460, and finally Vonitsa in 1479. With the exception of several coastal Venetian possessions, this was the end of Frankish rule in mainland Greece.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Despotate of Epirus


text:
The Medallion

The Medallion is a 2003 action comedy film directed by Hong Kong film director Gordon Chan, screenplay written by Bennett Joshua Davlin.

The film stars Jackie Chan, Lee Evans, Claire Forlani, and Julian Sands. It was much less successful than Chan's other American films such as the Rush Hour film series, Shanghai Noon and its sequel, Shanghai Knights. The film was theatrically released on 15 August 2003 in Hong Kong and 22 August 2003 in the United States by TriStar Pictures. However, on the home media release, it was released by Screen Gems.

In the story, Eddie (Jackie Chan) is a Hong Kong police officer hired by Interpol to capture a crime lord known as Snakehead (Sands) and stop him from kidnapping a chosen boy with special powers and a medallion that gives superhuman power and immortality.

Much of the film features supernatural and mystical themes, though it is filled with action and comedy. The film received negative reviews from critics. Even though the film's United States box office result was strong enough for Sony/TriStar Pictures to make profit, the film performed poorly at the box-office, and only grossed $34.3 million in worldwide box office against $35‒41 million production budget.

Plot
Eddie Yang is a Hong Kong police inspector cooperating with Interpol in the capture of a crime lord named AJ "Snakehead" Staul. Snakehead procures an ancient book from a Chinese bookstore keeper, which tells the story of a boy chosen every thousand years to bind the two halves of a legendary medallion. In Hong Kong, Eddie and Interpol agent Arthur Watson led a raid to capture Snakehead and his men, who were about to kidnap the boy named Jai. Eddie and the agents fight off Snakehead's men, infiltrating the temple containing Jai. The agents save Jai, but Snakehead eludes them. Two weeks later, Snakehead captures Jai aboard a cargo boat in Hong Kong. Eddie and a team of Hong Kong police engage and defeat several of Snakehead's men, but Snakehead escapes with Jai to Dublin, Ireland.

In Ireland, Eddie was assigned to help Interpol with the investigation, much to Watson's annoyance. Eddie also reunites with his girlfriend, a British Interpol agent named Nicole James. By chance, Eddie later encounters and apprehends one of Snakehead's top men, who confesses Jai gets held in the harbor. Eddie, Watson, and Nicole move to rescue Jai, defeating several Snakehead agents. Eddie and Jai end up trapped inside a container, which is knocked into the water by one of Snakehead's men before they can be released. Eddie keeps Jai alive by finding an inflatable tent and securely putting Jai inside, but Eddie suddenly dies from drowning. After being saved, Jai uses his medallion on Eddie's body.

In the morgue, Watson grieves over Eddie's body and prepares to say his last words, but Eddie appears beside him. Eddie finds out that Jai used the medallion to bring him back to life, and his former body vanishes into dust. Jai splits the medallion into its two halves, giving one of them to Eddie. Snakehead's men appear in the hospital to recapture Jai, and during the fight, Eddie discovers the medallion has also granted him superhuman strength and immortality.

Nicole looks after Jai, but he is captured again by Snakehead. At his castle hideout, Snakehead forces Jai to activate the medallion so he can gain its power with only one-half of it; Snakehead only gains superhuman strength and remains mortal. To steal the other half, Snakehead and his men attack Watson's family. Watson's Chinese wife reveals herself to be a police operative like him, much to Watson's surprise, as he kept his job secret from his family. Together, they fight off the attack from Snakehead's men.

Eddie, Watson, and Nicole learn the location of Snakehead's castle lair and go to finish him once and for all. The operation runs smoothly, but Snakehead kills Nicole and becomes immortal. He and Eddie engage in a vicious fight until Eddie uses the medallion to take away the life it gave, leading to the serpent and fish from the medallion appearing and bringing Snakehead, which traps him in the medallion. Jai allows Eddie to use the medallion to resurrect Nicole, who gains super-strength and immortality. The two then run in superhuman speed into the distance as Jai enters another dimension through a portal, scaring Watson.

Cast

 * Jackie Chan as Inspector Eddie Yang
 * Lee Evans as Interpol Inspector Arthur Watson
 * Claire Forlani as Inspector Nicole James
 * Alex Bao as Jai
 * Julian Sands as Snakehead/AJ Staul
 * Johann Myers as Giscard
 * John Rhys-Davies as Commander Hammerstock-Smythe
 * Anthony Wong as Lester Wong (Snakehead's assistant)
 * Christy Chung as Charlotte Watson
 * Billy Hill as Miles Watson
 * Nicholas Tse as waiter at the restaurant (cameo)
 * Edison Chen as waiter at the restaurant (cameo)

Snakehead's henchmen

 * Scott Adkins
 * Bruce Khan
 * Han Guan Hua
 * Paul Andreovski
 * Nicola Berwick
 * Reuben Langdon (as Reuben Christopher Langdon)
 * Hiro Hayama (as Hiroyoshi Komuro)
 * Mark Strange (as Michael Strange)
 * Matt Routledge (as Matthew James Routledge)
 * Chris Torres (uncredited)
 * Brad Allan (uncredited)
 * Jude Poyer (uncredited)

Production
With a projected budget of $35 million, the film was at the time the most expensive Hong Kong production ever, making Bennett Joshua Davlin the highest paid screenwriter in Asia.

Original plot and conception
Highbinders was the film's working title. In the original plot, those who were given power by the medallion became Highbinders, and Snakehead's goal was to create a Highbinder army at his disposal.

According to the editors' commentary, The Medallion wasn't American-made. However, Columbia-TriStar bought the distribution and editing rights worldwide except in Japan, France, and Hong Kong (but these three countries retain the American cut of the film, the only cut ever made). The original cut was meant to be around 108 minutes. The plot of the film explained Snakehead's crime syndicate of human smuggling, the deaths that occurred from it, and his desire to create an army of Highbinders to aid his organization. These details were all cut to focus on the medallion. As a result of several scene cuts, some original dialogue was overdubbed, including a small amount of Cantonese dialogue.

Over 20 minutes of these deleted scenes can be viewed on the U.S. DVD. Among these scenes are alternate endings where Eddie prevents Nicole's death, an extended fight sequence between Eddie and Snakehead's men, and an alternate ending to the chase sequence between Eddie and Giscard.

Filming
Filming took place in August 2001 in Dublin, Ireland. Production took a break while Jackie Chan shot 'The Tuxedo', and production resumed in Asia later that year. Filming took place in Dublin Castle, and in the Wicklow countryside. The filmmakers had initially planned to shoot scenes in Australia but were convinced to film in Dublin instead.

Box office
In its US release, The Medallion was No. 5 at the box office on its opening weekend and fell steadily lower during its 10-week release. Overall, it has earned $22.2 million, ranking No. 42 among all martial arts films released in the US and eighth among the Jackie Chan films distributed in the US. The US box office performance had exceeded Sony/TriStar Pictures' profitability target ('mid-teens' box office target).

Critical response
The film received generally negative reviews from critics. On Rotten Tomatoes the film has a rating of 17% based on reviews from 125 critics. The site's consensus states: "The use of special effects diminishes some of Chan's appeal in this disposable picture." On Metacritic the film has a score of 38% based on reviews from 30 critics, indicating "generally unfavorable reviews". Audiences surveyed by CinemaScore gave the film a grade B.

 * Mick LaSalle, San Francisco Chronicle: "The best of Jackie Chan's American movies, a pleasant little action comedy that makes one wonder how other filmmakers could ever get it wrong."
 * Roger Ebert, Chicago Sun-Times: "A disposable entertainment, redeemed by silliness, exaggeration, and Chan's skill and charm. I would not want to see it twice, but I liked seeing it once." Ebert called it an improvement over The Tuxedo but not as good as Shanghai Knights.
 * Steven Rea, Philadelphia Inquirer: "Chan's signature mix of screwball comedy and gymnastic derring-do landed him his own cartoon series a few years back, and The Medallion -- with its bumbling spies and bounding star -- is about as cartoonish as live action gets."

 * Dennis Harvey, Variety: "At times plays as if it were aimed at children, but more often simply seems to be aiming blind at whatever genre cliche the five credited writers fix upon in any given scene."
 * Wesley Morris, Boston Globe: "Moves from cheekiness to ineptitude, often in a single take."
 * Jami Bernard, New York Daily News: "Evans fumbles through painfully extended homophobic jokes, weak double entendres and agonizingly contorted double-takes."
 * Marc Savlov, Austin Chronicle: "One of the Peking Opera-trained superstar's most mediocre films, rivaling last year's God-awful The Tuxedo for sheer messy filmmaking and brazen acts of tedium... Abysmal."

Accolades

 * 23rd Hong Kong Film Awards
 * Nomination: Best Action Choreography (Sammo Hung)
 * Nomination: Best Visual Effects (Matthew Gidney)

title: The Medallion


text:
Rush Hour 2

Rush Hour 2 is a 2001 American buddy cop action comedy film directed by Brett Ratner and written by Jeff Nathanson. A sequel to Rush Hour (1998), it is the second installment in the Rush Hour franchise and stars Jackie Chan and Chris Tucker reprising their roles from the first film. The story follows Chief Inspector Lee (Chan) and LAPD Detective James Carter (Tucker), who go to Hong Kong on vacation only to be thwarted by a murder case involving two U.S. customs agents after a bombing at the American embassy. Lee suspects that the crime is linked to the Triad crime lord Ricky Tan (Lone).

Rush Hour 2 opened on August 3, 2001, to generally mixed reviews. The film was a commercial success, grossing $347.3 million worldwide, making it the highest-grossing film in the franchise. It also became the year's 11th-highest-grossing film worldwide as well as the second-highest-grossing PG-13-rated film. A sequel, Rush Hour 3, was released on August 10, 2007.

Plot
A few days after rescuing a Chinese diplomat's daughter, LAPD Detective James Carter is in Hong Kong on vacation with his friend, Hong Kong Police Force Chief Inspector Lee. His vacation is put on hold when a bomb at the US Consulate General kills two undercover US Customs agents. Lee is assigned to the case and discovers that his late father's police partner, Ricky Tan, is somehow involved. Lee and Carter attempt to question Ricky, now a leader of a crime gang known as the Triads, resulting in a brawl with his bodyguards.

The U.S. Secret Service, led by Agent Sterling, and the Hong Kong Police Force fight over jurisdiction of the case. Lee's office is bombed and Lee, unaware Carter has left the building, believes him dead. They cross paths at a party on Ricky's yacht, where Ricky scolds his underling, Hu Li. Lee and Carter confront Ricky, who claims he is being framed by his enemies and asks for protection, but Hu Li shoots him and escapes. Sterling holds Lee responsible for Ricky's death and orders him off the case. Carter is ordered back to Los Angeles, but convinces Lee to return to Los Angeles with him, after Lee tells him about Tan’s history with his father, leading up until his death. Seeing this as an opportunity for Lee to finally square his father’s death.

Carter assures Lee that every large criminal operation has a rich white man behind it; in this case, he believes that man is Steven Reign, a billionaire Los Angeles hotelier he saw acting suspiciously at Ricky Tan's party. Staking out Reign Towers, they spot Isabella Molina, whom Carter met on Ricky's yacht, receiving a delivery from Hu Li. Mistaking the package for another bomb, Lee and Carter try to intervene, but Molina reveals she is an undercover U.S. Secret Service agent, looking into Reign's laundering of $100 million in superdollars, with the only difference being that they burn with a red color unlike real dollars.

Lee and Carter visit Kenny, an ex-con, now Carter’s informant who runs a gambling den in the back of his Chinese restaurant. He tells them about a customer with a suspicious amount of hundred-dollar bills, which Carter confirms are Reign's counterfeits. They trace the money to a bank, where they are captured by Hu Li and the Triads. Taken to Las Vegas in a Triad truck, Lee and Carter escape, realizing that Reign is laundering the $100 million through his new Red Dragon Casino.

At the Red Dragon, Molina points Lee to the engraving plates used to print the counterfeit money, while Carter creates a distraction to help Lee sneak past security. Hu Li captures Lee, taping a Ying Tao grenade in his mouth before bringing him to Ricky, who is still alive. When Ricky departs, Molina tries to arrest Hu Li but is shot, and Lee and Carter manage to remove the grenade before Hu Li detonates it, evacuating the casino.

Carter fights Hu Li, accidentally taking her out with a spear, while Lee pursues Ricky. In the penthouse, Reign prepares to escape with the plates but Ricky fatally stabs him. Lee and Carter confront Ricky, who admits to killing Lee's father. In the ensuing scuffle, Ricky falls to his death when Lee accidentally kicks him out of the window, avenging Lee’s father’s death. Hu Li enters the room with a time bomb, forcing Lee and Carter to escape on a makeshift zip line as Hu Li dies in the explosion.

Later at the airport, Sterling and Molina thank Lee for his work on the case and Molina kisses him. Planning to go their separate ways when Lee gives Carter his late father’s police badge after finally finding closure for his father’s death, Lee and Carter change their minds when Carter reveals the large amount of money he won at the casino, and the pair head to New York City to indulge themselves while performing a victory dance to Michael Jackson’s "Don't Stop 'Til You Get Enough".

Cast
Jeremy Piven, Saul Rubinek, and Gianni Russo have cameo appearances as a Versace salesman, a casino box man, and a pit boss respectively.
 * Jackie Chan as Chief Inspector Lee, a Hong Kong cop. He invites Carter to Hong Kong for a vacation but accepts a case involving Ricky Tan, the man who killed his father.
 * Chris Tucker as Detective James Carter, an LAPD detective who is in Hong Kong for vacation but quickly becomes entangled in an international investigation.
 * John Lone as Ricky Tan, a Triad gangster working with Steven Reign.
 * Zhang Ziyi as Hu Li, a Triad assassin and enforcer.
 * Roselyn Sánchez as Agent Isabella Molina of the Secret Service. She is working undercover, posing as a corrupt agent while also enlisting Lee and Carter to help her stop the Triads.
 * Alan King as Steven Reign, a corrupt Los Angeles businessman in league with the Triads to use his new casino to launder counterfeit money.
 * Harris Yulin as Special Agent-In-Charge Sterling
 * Kenneth Tsang as Captain Chin
 * Don Cheadle as Kenny, the owner of a Chinese restaurant in L.A. that also houses an illegal gambling den.
 * Joel McKinnon Miller as Tex

Filming
Filming took place between December 11, 2000 and April 30, 2001.

Fake-money controversy
The prop masters for the film created approximately $1trillion in fake money to be used as props in the film. The money was realistic enough that some of the film's extras pocketed it and attempted to spend it illegally outside of the production, which led to said fake money being confiscated and destroyed by the U.S. Secret Service.

Music
Lalo Schifrin returned to compose the score for the film. According to him, "The music for Rush Hour 2 is completely different from Rush Hour. The first 20–30 seconds of the main title is a reprise of the music from Rush Hour – but that's it." He said that Ratner had requested a "symphonic score", which he incidentally found suitable for Rush Hour 2:

For the sequel, he asked me to do a symphonic score. It was bigger than life – like an epic score. I ignored the comedy – the actors took care of that. I played to the chases and the danger. It's a serious score in the sense of an "epic" score, like Raiders of the Lost Ark or an Errol Flynn film. Also, you must realize that the symphony orchestra allows many more possibilities. Mozart didn't need a rhythm section to "drive". I was able to create a lot of energy without the use of drums and electric guitars and all that.

Schifrin performed the Rush Hour 2 score with the Hollywood Studio Symphony. Varèse Sarabande released the soundtrack album on compact disc in August 2001. In a 2001 interview with Dan Goldwasser for Soundtrack.Net, Schifrin was asked whether he would score Rush Hour 3, and he stated: "Oh, I'm not a prophet!" By 2007, he began composing the score for Rush Hour 3, which, is his last motion picture score.

Release
Before its August 3 release, Rush Hour 2 premiered on July 26, 2001, on-board the United Airlines Flight 1 from Los Angeles to Hong Kong renamed, "The Rush Hour Express". The Hong Kong Board of Tourism teamed up with United Airlines and New Line Cinema in a campaign that offered both trailers for the movie for passengers on all domestic United flights during July and August reaching an expected three million people, as well as Hong Kong travel videos to inspire tourists to visit the country where the film was set.

Box office
Rush Hour 2 earned $226.2 million in North America and an estimated $121.2 million in other countries, for a worldwide total of $347.3 million (surpassing Rush Hour and Rush Hour 3's worldwide box-office receipts). The film was ranked number one during its opening weekend, grossing $67.4 million at 3,118 locations. The film stayed in the Top 10 until October 11 (10 weeks total). It became one of the four 2001 films to generate $60 million in their first three days of release, with the others being Monsters, Inc., The Mummy Returns and Planet of the Apes. The film also had the fourth-highest opening weekend of all time, behind the latter two films and The Lost World: Jurassic Park. Additionally, Rush Hour 2 achieved two other records during its opening weekend, beating The Sixth Sense for having the biggest August opening weekend and Austin Powers: The Spy Who Shagged Me for scoring the largest opening weekend for a New Line Cinema film. The August opening weekend record would be held for six years before getting surpassed by The Bourne Ultimatum in 2007. Rush Hour 2 would hold the record for having the highest opening weekend for a comedy film until 2002 when Austin Powers in Goldmember surpassed it. Despite being overtaken by American Pie 2, the film made $31.5 million during its second weekend. It was 2001's second-highest-grossing rated PG-13 film and the 11th highest-grossing film worldwide. Rush Hour 2 surpassed the 1984 film The Karate Kid as the highest-grossing martial arts action film, and was ranked as the second-highest-grossing buddy comedy film, behind the 1997 film Men in Black. The film was also ranked as the third-highest-grossing second installment in a live action comedy film franchise (behind the 2004 film Meet the Fockers and the 2011 film The Hangover Part II).

Reception
Reviews for Rush Hour 2 were mixed. On Rotten Tomatoes, the film has an approval rating of 52% based on 128 reviews, with an average rating of 5.4/10. The website's critical consensus states that the film "doesn't feel as fresh or funny as the first, and the stunts lack some of the intricacy normally seen in Chan's films." On Metacritic, the film has a score of 48 out of 100 based on 28 reviews, indicating "mixed or average reviews". Audiences polled by CinemaScore during Rush Hour 2 opening weekend gave the film an average grade of A on an A+ to F scale.

Roger Ebert gave it one and half stars out of a possible four calling Chris Tucker "an anchor around the ankles of the humor" in the movie. Conversely Robert Koehler of Variety called it a "superior sequel" and "the very model of the limber, transnational Hollywood action comedy".

Awards
Rush Hour 2 earned 27 award nominations and 10 wins, including an MTV Movie Award for Best Fight, a Teen Choice Award for Film-Choice Actor, Comedy, and 3 Kids' Choice Awards: Favorite Movie Actor for Tucker, Favorite Male Butt Kicker for Chan, and Favorite Movie.

Sequel
Because of various issues during development hell and production, Rush Hour 3 wasn't released until August 10, 2007; six years after Rush Hour 2. Rush Hour 3 failed to receive the critical and commercial acclaim of predecessors, but was still a box office success.

title: Rush Hour 2


text:
User talk:Poo eater

Hello, welcome to Wikipedia. You might wish to choose a different user name; ones that others are likely to find offensive are strongly discouraged-- see: Username. For other tips, see Welcome newcomers. -- Infrogmation 20:51, 13 May 2004 (UTC)

title: User talk:Poo eater


text: File:Vanishing point album cover.jpg

title: File:Vanishing point album cover.jpg


text:
Talk:Super Mario World

Luigi Sprite
Quote from the article: "In this version, Luigi has his own sprite (in the original, Luigi's sprite was simply a palette swap of the Mario sprite)".

I don't think this is correct. He's a palette swap in the original "Super Mario Bros.", but I think he has a taller, thinner sprite than Mario in SMW, in addition to being green. Pookiyama (talk) 15:54, 20 November 2012 (UTC)

On contrary to the above statement this depends on the version of Super Mario World you are playing. In Super Mario All Stars and Super Mario Advance 2, Luigi was given his own sprites where his height has been adjusted and some of his physics altered to match what Super Mario Bros: The Lost Levels (SMB2: Japan). EDIT: I Just realized this was already added in the additional versions of the game. My mistake. DioShiba (talk) 15:53, 31 October 2023 (UTC)DioShiba

Room for Improvement
This article is good, but it could be a lot better. So I am proposing some changes/alterations to it. First off, it needs more visual examples of gameplay. Second, the gameplay section has been divided into more paragraphs to make it more aesthetically pleasing and readable. And finally, could we expand a little bit on the gameplay itself? EnglishEfternamn *t/c*  20:30, 25 June 2013 (UTC)

External links modified
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30th Anniversary TFA:
The game's 30th anniversary is 21 November 2020. I think that'd be a good time to run it on the front page. Harizotoh9 (talk) 04:21, 10 April 2019 (UTC)

Save Points:
Somebody is continually reverting edits so that this page displays an inaccurate description of the game's save behaviour. You cannot continue from "the last level played" upon a game over. You -- as explained in Section 10 of the game's instruction manual -- return to the last save point, which is a fortress, castle or ghost house. Perhaps the "last level played" behaviour is accurate to the GBA or other ports of the game, but it is not accurate for the original SNES/Famicom version. Please, stop silently reverting this edit. LegalUsername (talk) 22:16, 20 January 2020 (UTC)

"Super Maio Wolrd" listed at Redirects for discussion
A discussion is taking place to address the redirect Super Maio Wolrd. The discussion will occur at Redirects for discussion/Log/2020 May 14 until a consensus is reached, and readers of this page are welcome to contribute to the discussion. Regards, SONIC  678  15:16, 14 May 2020 (UTC)

Recording for Spoken Wikipedia project
I intend to record this article for WikiProject Spoken Wikipedia in advance of it being featured on the front page of Wikipedia. I just did some light copy edits to make it more readable. SimLibrarian (talk) 08:16, 18 November 2020 (UTC)
 * I hope you're good at received pronunciation ;) JAG  UAR   10:40, 18 November 2020 (UTC)
 * Alas, you'll be *receiving* my Californian American English. A disappointment to the princess, I know. SimLibrarian (talk) 18:54, 18 November 2020 (UTC)
 * Recording completed and added. This is my first article reading, so please let me know if anything's not right! SimLibrarian (talk) 00:12, 19 November 2020 (UTC)
 * Thank you, it's perfect! It seems Californian is not so unorthodox after all! JAG  UAR   00:55, 21 November 2020 (UTC)

Edit request
This article is protected so I can’t edit it, but at the end of the re-releases section, is a newly added sentence “September 2017.[47]On September 5th 2019,...” A space is needed at the beginning of the sentence and the date needs changing to be consistent with the rest. Thanks. - 109.249.185.101 (talk) 14:25, 21 November 2020 (UTC)
 * ✅ Dexxor (talk) 14:38, 21 November 2020 (UTC)

worldmap image
I think one of the two copyrighted images should be the worldmap, since it's a big feature of the game. 205.175.106.39 (talk) 23:50, 21 November 2020 (UTC)

"Super Mario Brothers 2 Advance" listed at Redirects for discussion
An editor has identified a potential problem with the redirect Super Mario Brothers 2 Advance and has thus listed it for discussion. This discussion will occur at Redirects for discussion/Log/2022 October 10 until a consensus is reached, and readers of this page are welcome to contribute to the discussion. Pizzaplayer219TalkContribs 12:40, 10 October 2022 (UTC)

"3 up moon" listed at Redirects for discussion
An editor has identified a potential problem with the redirect 3 up moon and has thus listed it for discussion. This discussion will occur at Redirects for discussion/Log/2022 October 10 until a consensus is reached, and readers of this page are welcome to contribute to the discussion. Pizzaplayer219TalkContribs 12:49, 10 October 2022 (UTC)

British English
Can someone confirm to me why this article uses British English instead of American English? Nothing negative, just surprised. The articles for Super Mario Bros. 1, 2, 3, The Lost Levels, and All-Stars use American English, but not this. Carlinal (talk) 18:56, 10 February 2023 (UTC)

Gigaleak Assets
While I am certain that this could be linked back to the 2020 Nintendo Gigaleak, should this be touched upon in brief in regards to the Beta Assets? While I'm not sure how much we could talk about in regards to this topic I was wondering if it was worth going into discussion about. DioShiba (talk) 15:55, 31 October 2023 (UTC)

title: Talk:Super Mario World