title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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 impacts 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 impacts ranging from global warming potential, pollution, water depletion and others, are unavailable for PV. Instead, studies have tried to estimate the impact and potential impacts 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 impacts of their components and disposal methods are unknown, even for commercially available first generation solar cells, let alone experimental prototypes with no commercial viability.


title: Photovoltaics

text: Thus, estimates of the environmental impacts 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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 to 8 years.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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 CO-eq/kWh ranges from 37.3 to 72.2 grams when installed in Southern Europe.


title: Photovoltaics

text: 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 CO-eq/kWh ranges from 28.5 to 69 grams when installed in Southern Europe.


title: Photovoltaics

text: 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 impacts. In one such study, conventional energy mix in Greece was compared to multi-si PV and found a 95% overall reduction in impacts including carcinogens, eco-toxicity, acidification, eutrophication, and eleven others.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: CdTe PV systems require less energy input in their production than other commercial PV systems per unit electricity production. The average CO-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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: Two new promising thin film technologies are copper zinc tin sulfide (CuZnSnS or CZTS), zinc phosphide (ZnP) 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 (ZnP) 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, ZnP, 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 ZnP offer good promise for these reasons, the specific environmental implications of their commercial production are not yet known. Global warming potential of CZTS and ZnP were found 38 and 30 grams CO-eq/kWh while their corresponding EPBT were found 1.85 and 0.78 years, respectively. Overall, CdTe and ZnP have similar environmental impacts 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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 to 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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').


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: Financial incentives for photovoltaics, such as feed-in tariffs (FITs), are 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: Likewise, the application of solar photovoltaics is growing rapidly and worldwide installed capacity reached about 515 gigawatts (GW) by 2018. 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 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: China has the world's largest solar power capacity, with 253 GW of installed capacity at the end-2020 compared with about 151 GW in the European Union, according to International Energy Agency data.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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%.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: Reported global warming potential impacts of CIGS ranges 20.5–58.8 grams CO-eq/kWh of electricity generated for different solar irradiation (1,700 to 2,200 kWh/m/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.


title: Photovoltaics

text: 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%.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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 m of PV. The average CO-eq/kWh for OPV is 54.922 grams.


title: Photovoltaics

text: 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).


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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, USA. 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).


title: Photovoltaics

text: 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%).


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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).


title: Photovoltaics

text: 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 electric generation has the highest power density (global mean of 170 W/m) among renewable energies.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

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


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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.


title: Photovoltaics

text: 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: Winged Victory of Samothrace

text: The Winged Victory of Samothrace, or the Nike of Samothrace, is a votive monument originally found on the island of Samothrace, north of the Aegean Sea. It is a masterpiece of Greek sculpture from the Hellenistic era, dating from the beginning of the 2nd century BC. It is composed of a statue representing the goddess Niké (Victory), whose head and arms are missing, and its base in the shape of a ship's bow.


title: Winged Victory of Samothrace

text: The total height of the monument is 5.57 meters including the socle; the statue alone measures 2.75 meters. The sculpture is one of a small number of major Hellenistic statues surviving in the original, rather than Roman copies. "Winged Victory" has been exhibited at the Louvre Museum in Paris, at the top of the main staircase, since 1884.


title: Winged Victory of Samothrace

text: In 1863, Charles Champoiseau (1830–1909), acting in charge of the Consulate of France in Adrianopolis (now Edirne in Turkey), undertook from March 6 to May 7 the exploration of the ruins of the sanctuary of the Great Gods on the island of Samothrace. On April 13, 1863, he discovered part of the bust and the body of a large female statue in white marble accompanied by numerous fragments of drapery and feathers. He recognised this as the goddess Niké, Victory, traditionally represented in Greek antiquity as a winged woman. In the same place was a jumble of about fifteen large grey marble blocks whose form or function was unclear: he concluded it was a funerary monument. He decided to send the statue and fragments to the Louvre Museum, and to leave the large blocks of grey marble on site. Departing Samothrace at the beginning of May 1863, the statue arrived in Toulon at the end of August and in Paris on May 11, 1864.


title: Winged Victory of Samothrace

text: 1864-1866: a first restoration was undertaken by Adrien Prévost de Longpérier, then curator of Antiquities at the Louvre. The main part of the body (2.14 m, from the upper belly to the feet) is erected on a stone base, and largely completed by fragments of drapery, including the fold of himation that flares behind the legs on the Nike. The remaining fragments – the right part of the bust and a large part of the left wing – too incomplete to be placed on the statue, are stored. Given the exceptional quality of the sculpture, Longpérier decided to present the body alone, exhibited until 1880 among the Roman statues first in the Caryatid Room, then briefly in the Tiber Room.


title: Winged Victory of Samothrace

text: 1875: Austrian archaeologists who, under the direction of Alexander Conze, had been excavating the buildings of the Samothrace sanctuary since 1870, studied the location where Champoiseau had found the Victory. Architect Aloïs Hauser drew the grey marble blocks left on-site and apprehended that, once properly assembled, they form the tapered bow of a warship, and that, placed on a base of slabs, they served as the basis for the statue. Tetradrachmas of Demetrios Poliorcetes struck between 301 and 292 BCE. representing a Victory on the bow of a ship, wings outstretched, give a good idea of this type of monument. For his part, the specialist in ancient sculpture O. Benndorf is responsible for studying the body of the statue and the fragments kept in reserve at the Louvre, and restored the statue blowing into a trumpet that she raises with her right arm, as on the coin. The two men thus managed to make a model of the Samothrace monument as a whole.


title: Winged Victory of Samothrace

text: 1879: Champoiseau, informed of this research, undertook a second mission to Samothrace from August 15 to 29 for the sole purpose of sending the blocks of the base and the slabs of the Victory base to the Louvre. He abandoned on the island the largest block of the base, unsculpted. Two months later, the blocks reached the Louvre Museum, where in December an assembly test was carried out in a courtyard.


title: Winged Victory of Samothrace

text: 1880–1883: the curator of the Department of Antiquities, Félix Ravaisson-Mollien, then decided to reconstruct the monument, in accordance with the model of Austrian archaeologists. On the body of the statue, he restored the belt area in plaster, placed the right part of the marble bust, recreated the left part in plaster, attached the left marble wing with a metal frame, and replaced the entire right wing with a plaster model. But he did not reconstruct the head, arms or feet. The ship-shaped base is rebuilt and completed, except for the broken bow of the keel, and there is still a large void at the top aft. The statue was placed directly on the base. The entire monument was then placed from the front, on the upper landing of the Daru staircase, the main staircase of the museum.


title: Winged Victory of Samothrace

text: 1891: Champoiseau returned to Samothrace a third time to try to obtain the Victory's head, but without success. He did however bring back debris from the drapery and base, a small fragment with an inscription and fragments of coloured plaster.


title: Winged Victory of Samothrace

text: 1934: the presentation of the Victory is modified as part of a general redevelopment of the Daru museum and staircase, whose steps are widened and redecorated. The monument is staged to constitute the crowning of the staircase: it is advanced on the landing to be more visible from the bottom of the steps, and the statue is enhanced on the base by a modern 45 cm high block of stone, supposed to evoke a combat bridge at the bow of the ship. This presentation remained unchanged until 2013.


title: Winged Victory of Samothrace

text: 1939–1945: at the declaration of the Second World War in September 1939, the Victory statue descended from its base to be evacuated and sheltered with the other masterpieces of the Louvre Museum. It remained at the Château de Valençay (Indre) until the Liberation, and regained its place at the top of the stairs without damage in July 1945.


title: Winged Victory of Samothrace

text: 1950: American excavators from New York University, under the direction of Karl Lehmann, resumed exploration of the sanctuary of the Great Gods in Samothrace in 1938. In July 1950, they associated Louvre curator Jean Charbonneaux with their work, who discovered the palm of the statue's right hand in the Victory site. Two fingers preserved at the Kunsthistorische Museum in Vienna since the Austrian excavations of 1875 were reattached to the palm. The palm and fingers were then deposited in the Louvre Museum, and displayed with the statue since 1954.


title: Winged Victory of Samothrace

text: 1996: two pieces of grey marble that were used to moor fishing boats on the beach below the sanctuary were retrieved and reassembled at the museum in 1952. These were studied in 1996 by Ira Mark and Marianne Hamiaux, who concluded that these pieces, jointed, constitute the block of the base abandoned by Champoiseau in 1879.


title: Winged Victory of Samothrace

text: 2008–2014: the American team led by J. McCredie undertook the digitization of the entire sanctuary to allow its 3D reconstruction.


title: Winged Victory of Samothrace

text: 2013–2014: under the direction of B. D. Wescoat, resumption of the study of the Victory enclosure and the small basic fragments preserved in reserve began.


title: Winged Victory of Samothrace

text: 2013–2014: In Paris, the Louvre Museum undertook the restoration of the entire monument with two objectives: to clean all the dirty surfaces and improve the general presentation. The statue came down from its base to undergo scientific examination (UV, infrared, x-rays, microspectrography, marble analysis): traces of blue paint are detected on the wings and on a strip at the bottom of the mantle. The blocks of the base were disassembled one by one to be drawn and studied. The 19th-century restoration of the statue is preserved with a few details (thinning of the neck and attachment of the left arm), fragments preserved in reserve at the Louvre are added (feather at the top of the left wing, a fold at the back of the chitôn), the metal vice behind the left leg is removed. Castings of small joint fragments preserved in Samothrace are integrated into the base. A cast of the large ship block left in Samothrace was replaced by a metal base on a cylinder ensuring the proper balance of the statue. Once in place on the base, the colour contrast of the marbles of the two elements becomes obvious again. The whole is reassembled on a modern base, a little removed on the landing to facilitate the movement of visitors.


title: Winged Victory of Samothrace

text: The statue, in white Parian marble, depicts a winged woman, the goddess of Victory (Nikè), alighting on the bow of a warship.


title: Winged Victory of Samothrace

text: The Nike is dressed in a long tunic (chitôn) in a very fine fabric, with a folded flap and belted under the chest. It was attached to the shoulders by two thin straps (the restoration is not accurate). The lower body is partially covered by a thick mantle (himation) rolled up at the waist and untie when uncovering the entire left leg; one end slides between the legs to the ground, and the other, much shorter, flies freely in the back. The mantle is falling, and only the force of the wind holds it on her right leg. The sculptor has multiplied the effects of draperies, between places where the fabric is plated against the body by revealing its shapes, especially on the belly, and those where it accumulates in folds deeply hollowed out casting a strong shadow, as between the legs. This extreme virtuosity concerns the left side and front of the statue. On the right side, the layout of the drapery is reduced to the main lines of the clothes, in a much less elaborate work.


title: Winged Victory of Samothrace

text: The goddess advances, leaning on her right leg. The two feet that were bare disappeared. The right touched the ground, the heel still slightly raised; the left foot, the leg strongly stretched back, was still carried in the air. The goddess is not walking, she was finishing her flight, her large wings still spread out backwards. The arms disappeared, but the right shoulder raised indicates that the right arm was raised to the side. With her elbow bent, the goddess made her hand a victorious gesture of salvation: this hand with outstretched fingers held nothing (neither trumpet nor crown). There is no clue to reconstructing the position of the left arm, probably lowered, very slightly bent; the goddess may have held a "stylis" (a naval standard) on this side, a kind of mast taken as a trophy on the enemy ship, as seen on coins. The statue is designed to be seen three quarters left (right for the spectator), from where the lines of the composition are very clear: a vertical from the neck to the right foot, and an oblique starting from the neck diagonally along the left leg. "The whole body is inscribed in a rectangular triangle, a simple but very solid geometric figure: it was necessary to support both the fulfilled shapes of the goddess, the accumulation of draperies, and the energy of movement". Most recently the Alula feather was restored to the left wing in a flared position, as it would be for a bird landing.


title: Winged Victory of Samothrace

text: The art historian H. W. Janson has pointed out that unlike earlier Greek or Near Eastern sculptures, the Nike creates a deliberate relationship to the imaginary space around the goddess. The wind that has carried her and which she is fighting off, straining to keep steady – as mentioned the original mounting had her standing on a ship's prow, just having landed – is the invisible complement of the figure and the viewer is made to imagine it. At the same time, this expanded space heightens the symbolic force of the work; the wind and the sea are suggested as metaphors of struggle, destiny and divine help or grace. This kind of interplay between a statue and the space conjured up would become a common device in baroque and romantic art, about two thousand years later. It is present in Michelangelo's sculpture of David: David's gaze and pose shows where he is seeing his adversary Goliath and his awareness of the moment – but it is rare in ancient art.


title: Winged Victory of Samothrace

text: These are carved from grey marble veined with white, identified as that of the quarries of Lartos, in Rhodes. The base has the shape of the bow of a Greek Hellenistic warship: long and narrow, it is covered at the front by a combat deck on which the statue is located. It has reinforced, projecting oars boxes on the sides that supported two rows of staggered oars (the oval oar slots are also are depicted). The keel is rounded. At the bottom of the bow, at the waterline, was represented the large triple-pronged spur and a little higher up a smaller two-bladed ram: that would have been used to smash the hull of the enemy ship. The top of the bow was crowned by a high and curved bow ornament (the "acrostolion"). These missing elements have not been reconstructed, which greatly reduces the vessel's warlike appearance.


title: Winged Victory of Samothrace

text: Epigraphist Ch. Blinkenberg thought that this bow was that of a trihēmiolia, a type of warship often named in Rhodes inscriptions: the island's shipyards were renowned, and its war fleet important. But specialists in ancient naval architecture do not agree on the ascription of the trihemolia. It can only be said that the Samothrace bow has boxes of oars and two benches of superimposed oars. Each oar being operated by several rowers, this can also be suitable for a Quadrireme (4 files of rowers) or a Quinquereme (5 files of rowers). These ships were widespread in all Hellenistic war fleets, including the Rhodian fleet.


title: Winged Victory of Samothrace

text: The Victory statue, about 1.5 times lifesize, is not cut from a single block of marble, but composed of six blocks worked separately: the body, the bust with the head, the two arms and the two wings. These blocks were assembled together by metal braces (bronze or iron). This technique, used for a long time by Greek sculptors for the protruding parts of statues, was used in Hellenistic times for the body itself, thus making it possible to use smaller pieces of marble, therefore less rare and less expensive. In the case of Victory, the sculptor optimized this technique by tilting the joint surfaces that connect the wings to the body by 20° forward, which ensured their cantilevered support in the back. To the body-block was added smaller projecting pieces: the end of the flying mantle at the back and the end of the fold falling to the ground in front of the left leg have been reattached; the right foot, the back of the left leg with the foot and a drapery fold in front of the legs are lost.


title: Winged Victory of Samothrace

text: The ship is composed of 16 blocks divided into three increasingly wide assizes aft, placed on a rectangular base. The seventeenth block, which remained in Samothrace, completed the void at the back of the upper assembly, just under the statue. Its weight allowed the cantilever of the blocks of the protruding oar boxes to hold on the sides. The baseboard of the statue was embedded in a basin dug on this block. Its contours, fully visible during the 2014 restoration, made it possible to determine very precisely the location of the statue.


title: Winged Victory of Samothrace

text: The statue and base are inseparable to ensure the balance of the monument, designed as a whole. The construction of the monument was a real technical feat, a masterpiece of an artist who was not only a virtuoso sculptor.


title: Winged Victory of Samothrace

text: The sanctuary of the Great Gods of Samothrace is located in a very narrow river valley. The buildings reserved for the Mysteries ceremonies occupied the entire bottom of the valley. From the 3rd century BCE, the entrance to the site was a monumental propylaia to the east. To the west was a very long portico to house pilgrims (the stoa) and important offerings. The Victory Monument was located at the south end of the portico terrace, in a rectangular space dug into the hillside, and set back and raised from the theatre; facing north, it overlooks the entire sanctuary. In 1863 Champoiseau described and drew the monument surrounded on three sides by a limestone wall. All that remains of this enclosure now are the foundations of the walls, surrounded at the bottom and sides by walls supporting the lands of the hill. The enclosure itself is 13.40 m wide by 9.55 long, and we know from the surveys made by Hauser in 1876 that the Victory was arranged obliquely 14° 5 from the back wall. This arrangement highlights the left side of the statue for the observer from the terrace, which explains why the sculpture work is much more elaborate on this side than on the other. Large natural rocks are visible in the front part of space. The foundation walls have been restored and the place of the monument artificially indicated.


title: Winged Victory of Samothrace

text: The reconstructed whole has given rise to various interpretations. K. Lehmann hypothesized that the monument was placed in the basin of an open-air fountain, with water effects on the large rocks arranged for this purpose. But they could not be part of the original layout since the palm of the right hand was found under one of them: Charbonneau thought they came from a later natural landslide. The fountain hypothesis has been abandoned since the excavations of J. McCredie and B. Wescoat demonstrated that there was no water supply to the enclosure.


title: Winged Victory of Samothrace

text: Recent research has not determined the exact nature of the Victory's architectural setting, more than 500 blocks of which have been reused in a Byzantine construction at the other end of the west hill. Fragments of coloured plaster and some elements of terracotta architectural decoration were found in the enclosure. Two 3D reconstructions have been proposed by B. Wescoat: either low walls forming a peribolos around the open-air monument, or a covered building with columns and pediment of the naiskos type. The excellent state of conservation of the sculpture's surface suggests that it did not stay in the open air for long. The overall reconstruction of the sanctuary in 3D also highlighted that the statue of Victory was oriented along the axis of the river, which was the only unobstructed perspective of the sanctuary: the monument was thus clearly visible from the bottom of the valley.


title: Winged Victory of Samothrace

text: Another hypothesis was proposed by Jean Richer who observed that the Ship on which the statue is placed represents the constellation of the Argo: the ship's bow and the statue had been deliberately placed at an angle, within the important Sanctuary of the Great Gods of Samothrace, so that Victory looked northward: according to Richer, this direction shows the path that leads to the gate of the gods identified at Mount Hemos, and thus alludes to a spiritual victory; for, in this orientation, the momentum and gaze of the statue were directed at the northeast corner of the Anaktoron, seat of the Little Mysteries, where initiation was given. This angle was thus the most sacred of the building.


title: Winged Victory of Samothrace

text: In the sanctuary of the Great Gods of Samothrace, as in all the great pan-Hellenic shrines, the faithful offered their ex-votos, from the most modest to the most sumptuous according to their wealth. It was a way to honour the gods and thank them for their benefits. In addition to a promise of a better spiritual life, the Cabeiri gods, including the Dioscuri, were reputed to ensure their protection to those who were initiated into their Mysteries if they were in danger at sea and in combat. Summoning them allowed their initiates to be saved from shipwreck and to obtain victory. In this context, a representation of Victory landing on a ship's bow can be interpreted as an offering to thank the Great Gods following an important naval victory.


title: Winged Victory of Samothrace

text: Several major naval offerings were known in the 3rd century BC. In the Greek world, such as the "bull monument" in Delos, the naval monument of the agora in Cyrene and Samothrace itself, the Neorion, (No. 6 on the map), which housed a ship about twenty meters long. In Rhodes, an offering of the same type as the base of Samothrace, but smaller, was found in the sanctuary of Athena at the top of the acropolis of Lindos.


title: Winged Victory of Samothrace

text: The dedication inscription of the Victory Monument has not been found. Archaeologists are reduced to hypothesizing to define the historical context and to determine the naval victory justifying the erection of such an important ex-voto. The difficulty lies in the fact that in the 2nd and 3rd centuries BCE naval battles to dominate the Aegean Sea were very numerous, first pitting the Antigonids and their Seleucid allies against the Lagids, then the Seleucids to the Rhodians and Pergamon.


title: Winged Victory of Samothrace

text: Austrian archaeologists first considered that the monument of Samothrace is the one represented on the tetradrachma of Demetrios Poliorcetes. They conclude that, like the coin, he celebrated his victory against Ptolemy I at the Battle of Salamis at Cyprus in 306 BCE. According to Benndorf, the Victory of Samothrace therefore dates from the last years of the fourth century BC. and may have been sculpted by a student of sculptor Scopas.


title: Winged Victory of Samothrace

text: The construction of the monument was then related to the Battle of Cos (around 262–255 BCE)., during which the King of Macedonia Antigonus II Gonatas defeated the Lagids, allied with Athens and Sparta during the Chremonidean War. Antigonus Gonatas is also credited with the dedication, at the same time, of his flagship in the Neorium in Delos.


title: Winged Victory of Samothrace

text: The material of the base of the Victory of Samothrace was identified as early as 1905 as marble from the quarries of Lartos in Rhodes. The same is true of the small fragment found in 1891 by Champoiseau within the walls of the monument to Samothrace, bearing the end of an engraved name: [...]Σ ΡΟΔΙΟΣ. In 1931, Hermann Thiersch restored the name of the sculptor "Pythocritos son of Timocharis of Rhodes", active around 210–165 BCE. He is convinced that the fragment belongs to the ship-shaped base: he therefore makes this sculptor the author of the Victory of Samothrace. According to him, the monument was commissioned by the Rhodians, allies in the kingdom of Pergamos against Antiochus III, after their victory at the naval battles of Side and Myonnesos, on the Ionian coast, in 190 BCE. Excavations uncovered the sculpture was positioned alighting on a flagship, that was set in the ground in a way that it looked as it was floating. The definitive victory against the Seleucus came in 189 BCE. at the Battle of Sipyla Magnesia. The monument was therefore reportedly erected in Samothrace shortly after that date. Jean Charbonneaux also admits the historical link between the Victory of Samothrace and the battles of Myonnesus and Magnesia, and makes it the dedication of King Eumene II.


title: Winged Victory of Samothrace

text: Based on the same arguments, Nathan Badoud in 2018 favoured the conflict that earlier pitted the Rhodians and the King of Pergamon against King Philip V of Macedonia. The Rhodians were first defeated at the naval Battle of Lade in 201 BCE. Then Philip V was defeated at sea by the two allies at the Battle of Chios in 201 BCE. Persistent hostilities, Rhodes and Pergamon call the Roman Republic as reinforcements, and General Flamininus crushes the Macedonian army in Thessaly with the Battle of Cynoscephalae. The Rhodians reportedly dedicated the Victory Monument after that date, for their victory in Chios.


title: Winged Victory of Samothrace

text: Other researchers have considered later occasions: the victory of the Romans at Pydna in 168 BCE. over Perseus, or a consecration of the kingdom of Pergamon at the same time, or the victory of Pergamon and Rhodes against Prusias II of Bithynia in 154 BCE.


title: Winged Victory of Samothrace

text: Although the supposed dedication inscription of the name of a Rhodian found at the Victory's base was very quickly contested because of its small size, the entire monument remained attributed to the Rhodian sculpture school. This made it possible to put an end to previous hesitations about the style of the statue. In 1955 Margarete Bieber made him a major figure in the "Rhodian school" and the "Hellenic Baroque", next to the frieze of the Gigantomachy of the Great Altar of Pergamon, characterized by the strength of attitudes, the virtuosity of the draperies and the expressiveness of the figures. This style lasted in Rhodes until Roman times in complex and monumental creations such as the Laocoon group or Sperlonga sculptures attributed or signed by Rhodian sculptors.


title: Winged Victory of Samothrace

text: The base blocks and the sculpture of the statue are not by the same hand. The two parts of the monument were designed together, but produced by two different workshops. The marble base of Lartos was certainly made in Rhodes, where there are parallels. Moreover, the Rhodian sculpture in large marble is of high quality, without being exceptional for its time, but there are no parallels for the virtuosity of the Nike, which remains unusual. The sculptor could also come from elsewhere, as was common in the ancient Greek world for great artists. The Victory of Samothrace is a grandiose adaptation of the moving statue of the Athena-Niké of the Cyrene monument: the sculptor added wings, stretched out his front leg to express the flight, and modified the arrangement of the mantle with the floating panel at the back. He thus gives the statue of Samothrace a dynamic that brings it closer to the figures the Gigantomachy of the altar of Pergamon, conceived shortly after in the same spirit.


title: Percussion instrument

text: A percussion instrument is a musical instrument that is sounded by being struck or scraped by a beater including attached or enclosed beaters or rattles struck, scraped or rubbed by hand or struck against another similar instrument. Excluding zoomusicological instruments and the human voice, the percussion family is believed to include the oldest musical instruments. In spite of being a very common term to designate instruments, and to relate them to their players, the percussionists, percussion is not a systematic classificatory category of instruments, as described by the scientific field of organology. It is shown below that percussion instruments may belong to the organological classes of ideophone, membranophone, aerophone and cordophone.


title: Percussion instrument

text: The percussion section of an orchestra most commonly contains instruments such as the timpani, snare drum, bass drum, tambourine, belonging to the membranophones, and cymbals and triangle, which are idiophones. However, the section can "also" contain aerophones, such as whistles and sirens, or a blown conch shell. Percussive techniques can even be applied to the human body itself, as in body percussion. On the other hand, keyboard instruments, such as the celesta, are not normally part of the percussion section, but keyboard percussion instruments such as the glockenspiel and xylophone (which do not have piano keyboards) are included.


title: Percussion instrument

text: Percussion instruments are most commonly divided into two classes: pitched percussion instruments, which produce notes with an identifiable pitch, and unpitched percussion instruments, which produce notes or sounds in an indefinite pitch.


title: Percussion instrument

text: Percussion is commonly referred to as "the backbone" or "the heartbeat" of a musical ensemble, often working in close collaboration with bass instruments, when present. In jazz and other popular music ensembles, the pianist, bassist, drummer and sometimes the guitarist are referred to as the rhythm section. Most classical pieces written for full orchestra since the time of Haydn and Mozart are orchestrated to place emphasis on the strings, woodwinds, and brass. However, often at least one pair of timpani is included, though they rarely play continuously. Rather, they serve to provide additional accents when needed. In the 18th and 19th centuries, other percussion instruments (like the triangle or cymbals) have been used, again generally sparingly. The use of percussion instruments became more frequent in the 20th century classical music.


title: Percussion instrument

text: In almost every style of music, percussion plays a pivotal role. In military marching bands and pipes and drums, it is the beat of the bass drum that keeps the soldiers in step and at a regular speed, and it is the snare that provides that crisp, decisive air to the tune of a regiment. In classic jazz, one almost immediately thinks of the distinctive rhythm of the hi-hats or the ride cymbal when the word-swing is spoken. In more recent popular-music culture, it is almost impossible to name three or four rock, hip-hop, rap, funk or even soul charts or songs that do not have some sort of percussive beat keeping the tune in time.


title: Percussion instrument

text: Because of the diversity of percussive instruments, it is not uncommon to find large musical ensembles composed entirely of percussion. Rhythm, melody, and harmony are all represented in these ensembles. Usually started to be played at a younger age for more talented individuals, commonly started at age 10 - 12


title: Percussion instrument

text: Music for pitched percussion instruments can be notated on a staff with the same treble and bass clefs used by many non-percussive instruments. Music for percussive instruments without a definite pitch can be notated with a specialist rhythm or percussion-clef. The guitar also has a special "tab" staff. More often a bass clef is substituted for rhythm clef.based on the previous reservation


title: Percussion instrument

text: Percussion instruments are classified by various criteria sometimes depending on their construction, ethnic origin, function within musical theory and orchestration, or their relative prevalence in common knowledge.


title: Percussion instrument

text: The word percussion derives from the Latin verb "percussio" to beat, strike in the musical sense, and the noun "percussus", a beating. As a noun in contemporary English, Wiktionary describes it as the collision of two bodies to produce a sound. The term is not unique to music, but has application in medicine and weaponry, as in percussion cap. However, all known uses of "percussion" appear to share a similar lineage beginning with the original Latin percussus. In a musical context then, the "percussion instruments" may have been originally coined to describe a family of musical instruments including drums, rattles, metal plates, or blocks that musicians beat or struck to produce sound.


title: Percussion instrument

text: The Hornbostel–Sachs system has no high-level section for "percussion". Most percussion instruments as the term is normally understood are classified as idiophones and membranophones. However the term "percussion" is instead used at lower-levels of the Hornbostel–Sachs hierarchy, including to identify instruments struck with either a non sonorous object hand, stick, striker or against a non-sonorous object human body, the ground. This is opposed to "concussion", which refers to instruments with two or more complementary sonorous parts that strike against each other and other meanings. For example:


title: Percussion instrument

text: 111.1 "Concussion idiophones or clappers", played in pairs and beaten against each other, such as zills and clapsticks.


title: Percussion instrument

text: 111.2 "Percussion idiophones", includes many percussion instruments played with the hand or by a percussion mallet, such as the hang, gongs and the xylophone, but not drums and only some cymbals.


title: Percussion instrument

text: 412.12 "Percussion reeds", a class of wind instrument unrelated to "percussion" in the more common sense


title: Percussion instrument

text: Percussion instruments are sometimes classified as pitched or unpitched. While valid, this classification is widely seen as inadequate. Rather, it may be more informative to describe percussion instruments in regards to one or more of the following four paradigms:


title: Percussion instrument

text: Many texts, including "Teaching Percussion" by Gary Cook of the University of Arizona, begin by studying the physical characteristics of instruments and the methods by which they can produce sound. This is perhaps the most scientifically pleasing assignment of nomenclature whereas the other paradigms are more dependent on historical or social circumstances. Based on observation and experimentation, one can determine how an instrument produces sound and then assign the instrument to one of the following four categories:


title: Percussion instrument

text: Most objects commonly known as drums are membranophones. Membranophones produce sound when the membrane or head is struck with a hand, mallet, stick, beater, or improvised tool.


title: Percussion instrument

text: Most instruments known as chordophones are defined as string instruments, wherein their sound is derived from the vibration of a string, but some such as these examples "also" fall under percussion instruments.


title: Percussion instrument

text: Most instruments known as aerophones are defined as wind instruments whereby sound is produced by a stream of air being blown through the object. However, plosive aerophones, such as the udu, are percussion instruments and may also overlap with the idiophone family. In certain situations, such as in an orchestra or wind ensemble, wind instruments, such as the Acme siren or various whistles, are played by percussionists, owing to their unconventional and simple nature.


title: Percussion instrument

text: When classifying instruments by function it is useful to note if a percussion instrument makes a definite pitch or indefinite pitch.


title: Percussion instrument

text: For example, some percussion instruments such as the marimba and timpani produce an obvious fundamental pitch and can therefore play melody and serve harmonic functions in music. Other instruments such as crash cymbals and snare drums produce sounds with such complex overtones and a wide range of prominent frequencies that no pitch is discernible.


title: Percussion instrument

text: Instruments in this group are sometimes referred to as non-pitched, unpitched, or untuned. Traditionally these instruments are thought of as making a sound that contains such complex frequencies that no discernible pitch can be heard.


title: Percussion instrument

text: In fact many traditionally unpitched instruments, such as triangles and even cymbals, have also been produced as tuned sets.


title: Percussion instrument

text: It is difficult to define what is common knowledge but there are instruments percussionists and composers use in contemporary music that most people wouldn't consider musical instruments. It is worthwhile to "try" to distinguish between instruments based on their acceptance or consideration by a general audience.


title: Percussion instrument

text: For example, most people would not consider an anvil, a brake drum (on a vehicle with drum brakes, the circular hub the brake shoes press against), or a fifty-five gallon oil barrel musical instruments yet composers and percussionists use these objects.


title: Percussion instrument

text: One pre-20th century example of found percussion is the use of cannon usually loaded with blank charges in Tchaikovsky's "1812 Overture". John Cage, Harry Partch, Edgard Varèse, and Peter Schickele, all noted composers, created entire pieces of music using unconventional instruments. Beginning in the early 20th century perhaps with "Ionisation" by Edgard Varèse which used air-raid sirens among other things, composers began to require that percussionists invent or find objects to produce desired sounds and textures. Another example the use of a hammer and saw in Penderecki's "De Natura Sonoris No. 2". By the late 20th century, such instruments were common in modern percussion ensemble music and popular productions, such as the off-Broadway show, Stomp. Rock band Aerosmith used a number of unconventional instruments in their song Sweet Emotion, including shotguns, brooms, and a sugar bag. The metal band Slipknot is well known for playing unusual percussion items, having two percussionists in the band. Along with deep sounding drums, their sound includes hitting baseball bats and other objects on beer kegs to create a distinctive sound.


title: Percussion instrument

text: It is not uncommon to discuss percussion instruments in relation to their cultural origin. This led to a division between instruments considered common or modern, and folk instruments with significant history or purpose within a geographic region or culture.


title: Percussion instrument

text: The general term for a musician who plays percussion instruments is "percussionist" but the terms listed below often describe specialties:


title: Percussion instrument

text: Within rock music, the term "percussionist" is often used to refer to someone who plays percussion instruments but is not primarily a drummer. The term is especially found in bands where one person plays drums and another plays other hit instruments.


title: Sobibor extermination camp

text: Sobibor (, Polish: ) was an extermination camp built and operated by Nazi Germany as part of Operation Reinhard. It was located in the forest near the village of Żłobek Duży in the General Government region of German-occupied Poland.


title: Sobibor extermination camp

text: As an extermination camp rather than a concentration camp, Sobibor existed for the sole purpose of murdering Jews. The vast majority of prisoners were gassed within hours of arrival. Those not killed immediately were forced to assist in the operation of the camp, and few survived more than a few months. In total, some 170,000 to 250,000 people were murdered at Sobibor, making it the fourth-deadliest Nazi camp after Auschwitz, Treblinka, and Belzec.


title: Sobibor extermination camp

text: The camp ceased operations after a prisoner revolt which took place on 14 October 1943. The plan for the revolt involved two phases. In the first phase, teams of prisoners were to discreetly assassinate each of the SS officers. In the second phase, all 600 prisoners would assemble for evening roll call and walk to freedom out the front gate. However, the plan was disrupted after only eleven SS men had been killed. The prisoners had to escape by climbing over barbed wire fences and running through a mine field under heavy machine gun fire. About 300 prisoners made it out of the camp, of whom roughly 60 survived the war.


title: Sobibor extermination camp

text: After the revolt, the Nazis demolished most of the camp in order to hide their crimes from the advancing Red Army. In the first decades after World War II, the site was neglected and the camp had little presence in either popular or scholarly accounts of the Holocaust. It became better known after it was portrayed in the TV miniseries "Holocaust" (1978) and the film "Escape from Sobibor" (1987). The Sobibor Museum now stands at the site, which continues to be investigated by archaeologists. Photographs of the camp in operation were published in 2020 as part of the Sobibor perpetrator album.


title: Sobibor extermination camp

text: Sobibor was one of four extermination camps established as part of Operation Reinhard, the deadliest phase of the Holocaust. The extermination of Europe's Jews did not originate as a single top-down decision, but was rather a patchwork of decisions made regarding particular occupied areas. Following the invasion of Poland in September 1939, the Germans began implementing the Nisko Plan in which Jews were deported from ghettos across Europe to the forced labour camps which comprised the "Lublin Reservation". Lublin District region was chosen in particular for its inhospitable conditions. The Nisko Plan was abandoned in 1940, but many forced labour camps continued operations in the area, including Trawniki, Lipowa 7, and Dorohucza.


title: Sobibor extermination camp

text: In 1941, the Nazis began experimenting with gassing Jews. In December 1941, SS officials at Chełmno conducted experiments using gas vans and the first mass gassings were conducted at Auschwitz concentration camp in January. At the Wannsee Conference on 20 January 1942, Reinhard Heydrich announced a plan for systematically murdering the Jews through a network of extermination camps. This plan was realized as Operation Reinhard.


title: Sobibor extermination camp

text: Nothing is known for certain about the early planning for Sobibor in particular. Some historians have speculated that planning began as early as 1940, on the basis of a railway map from that year which omits several major cities but includes Sobibór and Bełżec. The earliest hard evidence for Nazi interest in the site comes from the testimony of local Poles, who noticed in Autumn 1941 that SS officers were surveying the land opposite the train station. When a worker at the station cafeteria asked one of the SS men what was being built, he replied that she would soon see and that it would be "a good laugh."


title: Sobibor extermination camp

text: In March 1942 "SS-Hauptsturmführer" Richard Thomalla took over construction work at Sobibor, which had begun at an unknown earlier date. Thomalla was a former building contractor and committed Nazi whose service as an auxiliary police commander and adviser on Jewish forced labour had earned him a high-ranking position in Odilo Globočnik's construction department. Having previously overseen the construction of Bełżec extermination camp, he applied lessons learned there to Sobibor. Thomalla allotted a much larger area for Sobibor than he had for Bełżec, allowing more room to maneuver as well as providing space for all of the camp's facilities to be constructed within its perimeter.


title: Sobibor extermination camp

text: The camp incorporated several pre-war buildings including a post office, a forester's lodge, a forestry tower, and a chapel. The forester's lodge became the camp administration building, while the post office was used as lodging for the SS (though not, as commonly reported, for the commandant). The former post office, located near the railroad tracks, still stands today. The SS adapted the preexisting railroad infrastructure, adding an 800-meter railroad spur that ended inside the camp. This third set of tracks allowed regular rail traffic to continue uninterrupted while the camp unloaded transports of new prisoners. Some building materials were supplied by the SS Central Construction Office in Lublin, while others were procured from local sawmills and brickworks, as well as from the remains of demolished houses of Jews.


title: Sobibor extermination camp

text: The first group of workers who built the camp were primarily locals from neighbouring villages and towns. It is unknown to what extent these were Polish or Jewish forced labourers. After Thomalla's arrival, the Jewish council in nearby Włodawa was ordered to send 150 Jews to assist in the construction of the camp. These workers were constantly harassed as they worked, and were shot if they showed signs of exhaustion. Most were murdered upon completion of construction, but two escaped back to Włodawa, where they attempted to warn the Jewish council about the camp and its purpose. Their warnings were met with disbelief.


title: Sobibor extermination camp

text: The first gas chambers at Sobibor were built following the model of those at Belzec, but without any furnaces. To provide the carbon monoxide gas, "SS-Scharführer" Erich Fuchs acquired a heavy gasoline engine in Lemberg, disassembled from an armoured vehicle or a tractor. Fuchs installed the engine on a cement base at Sobibor in the presence of SS officers Floss, Bauer, Stangl, and Barbl, and connected the engine exhaust manifold to pipes leading to the gas chamber. In mid-April 1942, the Nazis conducted experimental gassings in the nearly finished camp. Christian Wirth, the commander of Bełżec and Inspector of Operation Reinhard, visited Sobibor to witness one of these gassings, which murdered thirty to forty Jewish women brought from the labour camp at Krychów.


title: Sobibor extermination camp

text: The initial construction of Sobibor was finished by summer 1942, and a steady stream of prisoners began thereafter. However, the SS camp was continuously expanded and renovated throughout its existence. After only a few months of operation, the wooden walls of the gas chambers had absorbed too much sweat, urine, blood, and excrement to be cleanable. Thus, the gas chambers were demolished in the summer of 1942, and new larger ones were built made out of brick. Later that summer, the SS also embarked on a beautification project, instituting a more regular cleaning schedule for the barracks and stables, and expanding and landscaping the "Vorlager" to give it the appearance of a "Tyrolean village" much noted by later prisoners. When Sobibor ceased operations in mid-1943, the SS were part way through the construction of a munitions depot known as Lager IV.


title: Sobibor extermination camp

text: Sobibor was surrounded by double barbed wire fences which were thatched with pine branches in order to block the view inside. At its southeast corner, it had two side-by-side gates; one for trains and another for foot traffic and vehicles. The site was divided into five compounds: the "Vorlager" and four "Lagers" numbered "I-IV".


title: Sobibor extermination camp

text: The "Vorlager" (front compound) contained living quarters and recreational buildings for the camp personnel. The SS officers lived in cottages with colorful names such as "Lustiger Floh" (the Merry Flea), "Schwalbennest" (the Swallow's Nest), and "Gottes Heimat" (God's Own Home). They also had a canteen, a bowling alley, a hairdresser, and a dentist, all staffed by Jewish prisoners. The watchmen, drawn from Soviet POWs, had separate barracks, and their own separate recreational buildings, including a hair salon and a canteen.


title: Sobibor extermination camp

text: The Nazis paid great attention to the appearance of the "Vorlager". It was neatly landscaped, with lawns and gardens, outdoor terraces, gravel-lined paths, and professionally painted signs. This idyllic appearance helped hide the nature of the camp from prisoners, who would arrive on the adjacent ramp. Survivor Jules Schelvis recalled feeling reassured upon arrival by the "Vorlager's" "Tyrolean cottage-like barracks with their bright little curtains and geraniums on the windowsills".


title: Sobibor extermination camp

text: "Lager I" contained barracks and workshops for the prisoners. These workshops included a tailor's shop, a carpenter's shop, a mechanic's shop, a sign-painter's shop, and a bakery. "Lager I" was accessible only through the adjacent "Vorlager", and its western boundary was made escape-proof with a water-filled trench.


title: Sobibor extermination camp

text: "Lager II" was a larger multi-purpose compound. One subsection called the ""Erbhof"" contained the administration building, as well as a small farm. The administration building was a pre-war structure previously used by the local Polish forestry service. As part of the camp, this building was adapted to provide accommodation for some SS officers, storage for goods stolen from victims' luggage, as well as a pharmacy, whose contents were also taken from victims' luggage. On the farm, Jewish prisoners raised chickens, pigs, geese, fruits and vegetables for consumption by the SS men.


title: Sobibor extermination camp

text: Outside the "Erbhof", "Lager II" contained facilities where new arrivals were prepared before being murdered. It contained the sorting barracks and other buildings used for storing items taken from the victims, including clothes, food, hair, gold, and other valuables. At the east end was a yard where new arrivals had their luggage taken from them and were forced to undress. This area was beautified with flower beds to hide the camp's purpose from newcomers. This yard led into the narrow enclosed path called the "Himmelstrasse" (road to heaven) or the "Schlauch" (tube), which led straight to the gas chambers in "Lager III". The "Himmelstrasse" was covered on both sides by fences woven with pine branches.


title: Sobibor extermination camp

text: "Lager III" was the extermination area. It was isolated from the rest of the camp, set back in a clearing in the forest and surrounded by its own thatched fence. Prisoners from "Lager I" were not allowed near it, and were killed if they were suspected of having seen inside. Due to a lack of eyewitness testimony, little is known about "Lager III" beyond the fact that it contained gas chambers, mass graves, and special separate housing for the Sonderkommando prisoners who worked there.


title: Sobibor extermination camp

text: "Lager IV" (also called the "Nordlager") was added in July 1943, and was still under construction at the time of the revolt. Located in a heavily wooded area to the north of the other camps, it was being developed as a munitions depot for processing arms taken from Red Army soldiers.


title: Sobibor extermination camp

text: Because Sobibor was an extermination camp, the only prisoners who lived there were the roughly 600 slave labourers forced to assist in the operation of the camp. While survivors of Auschwitz use the term "selected" to mean being selected for murder, at Sobibor being "selected" meant being selected to live, at least temporarily. The harsh conditions in the camp took the lives of most new arrivals within a few months.


title: Sobibor extermination camp

text: Prisoners worked from 6:00 am to 6:00 pm, with a short lunch break in the middle. Sundays were designated as half days, but this policy was not always observed. The prisoner population included many labourers with specialized skills such as goldsmithing, painting, gardening, or tailoring. While such prisoners were officially spared death only to support the camp's primary operations, much of their labour was in fact diverted for the SS officers' personal enrichment. Renowned Dutch Jewish painter Max van Dam was nominally kept as a sign painter, but the SS also forced him to paint landscapes, portraits, and hagiographic images of Hitler. Similarly, Shlomo Szmajzner was placed in charge of the machine shop in order to conceal his work making gold jewelry for SS officers. Prisoners with specialized skills were considered especially valuable and were afforded privileges not available to others.


title: Sobibor extermination camp

text: Those without specialized skills performed a variety of other jobs. Many worked in the "Lager II" sorting barracks, where they were forced to comb through luggage left behind by gas chamber victims, repackaging valuable items as "charity gifts" for German civilians. These workers could also be called on to serve in the railway brigade which greeted new prisoners. The railway brigade was considered a relatively appealing job, since it gave famished workers access to luggage which often contained food. Younger prisoners commonly worked as "putzers", cleaning for the Nazis and the watchmen and attending to their needs. A particularly horrifying job was that of the "barbers" who cut the hair of women on their way to the gas chamber. This job was often forced upon young male prisoners in an attempt to humiliate both them and the naked women whose hair they were cutting. Armed watchmen supervised the process in order to ensure that barbers did not respond to victims' questions or pleas.


title: Sobibor extermination camp

text: In "Lager III", a special unit of Jewish prisoners was forced to assist in the extermination process. Its tasks included removing bodies, searching cavities for valuables, scrubbing blood and excrement from the gas chambers, and cremating the corpses. Because the prisoners who belonged to this unit were direct witnesses to genocide, they were strictly isolated from other prisoners and the SS would periodically liquidate those unit members who had not already succumbed to the work's physical and psychological toll. Since no workers from "Lager III" survived, nothing is known about their lives or experiences.


title: Sobibor extermination camp

text: When construction of "Lager IV" began in the summer of 1943, the Nazis assembled a forest commando who worked there cutting timber for heat, cooking, as well as cremation pyres.


title: Sobibor extermination camp

text: Prisoners struggled with the fact that their labour made them complicit in mass murder, albeit indirectly and unwillingly. Many committed suicide. Others endured, finding ways to resist, if only symbolically. Common symbolic forms of resistance included praying for the dead, observing Jewish religious rites, and singing songs of resistance. However, some prisoners found small ways of materially fighting back. While working in the sorting shed, Saartje Wijnberg would surreptitiously damage fine items of clothing to prevent them from being sent to Germany. After the war, Esther Terner recounted what she and Zelda Metz did when they found an unattended pot of soup in the Nazis' canteen: "We spit in it and washed our hands in it... Don't ask me what else we did to that soup... And they ate it."


title: Sobibor extermination camp

text: Prisoners found it difficult to forge personal relationships. This was in part due to the constant turnover in the camp population, but also to an atmosphere of mutual distrust which was often exacerbated by national or linguistic divisions. Dutch Jews were particularly subject to derision and suspicion because of their assimilated manners and limited Yiddish. German Jews faced the same suspicion as the Dutch, with the added implication that they might identify more with their captors than with their fellow prisoners. When social groups did form, they were generally based on family ties or shared nationality, and were completely closed off to outsiders. Chaim Engel even found himself shunned by fellow Polish Jews after he began a romantic relationship with Dutch-born Saartje Wijnberg. These divisions had dire consequences for many prisoners from Western Europe, who were not trusted with crucial information about goings-on in the camp.


title: Sobibor extermination camp

text: Because of the expectation of imminent death, prisoners adopted a day-at-a-time outlook. Crying was rare and evenings were often spent enjoying whatever of life was left. As revolt organizer Leon Feldhendler recounted after the war, “The Jews only had one goal: "carpe diem", and in this they simply went wild.” Prisoners sang and danced in the evenings and sexual or romantic relations were frequent. Some of these affairs were likely transactional or coerced, especially those between female prisoners and "kapos", but others were driven by genuine bonds. Two couples that met in Sobibor were married after the war. The Nazis allowed and even encouraged an atmosphere of merriment, going so far as to recruit prisoners for a choir at gunpoint. Many prisoners interpreted these efforts as attempts by the Nazis to keep the prisoners docile and to prevent them from thinking about escape.


title: Sobibor extermination camp

text: Prisoners had a pecking order largely determined by one's usefulness to the Germans. As survivor Toivi Blatt observed, there were three categories of prisoners: the expendable "drones" whose lives were entirely at the mercy of the SS, the privileged workers whose special jobs provided some relative comforts, and finally the artisans whose specialized knowledge made them indispensable and earned them preferential treatment. Moreover, as at other camps, the Nazis appointed "kapos" to keep their fellow prisoners in line. "Kapos" carried out a variety of supervisory duties and enforced their commands with whips. "Kapos" were involuntary appointees, and they varied widely in how they responded to the psychological pressures of their position. "Oberkapo" Moses Sturm was nicknamed "Mad Moisz" for his mercurial temperament. He would beat prisoners horrifically without provocation and then later apologize hysterically. He talked constantly of escape, sometimes merely berating the other prisoners for their passivity, other times attempting to formulate actionable plans. Sturm was executed after being betrayed by a lower ranking "kapo" named Herbert Naftaniel. Naftaniel, nicknamed "Berliner", was promoted to "Oberkapo" and became a notorious figure in the camp. He viewed himself as German rather than Jewish, and began a reign of terror which came to an end shortly before the revolt, when a group of prisoners beat him to death with "SS-Oberscharfuhrer" Karl Frenzel's permission.


title: Sobibor extermination camp

text: Despite these divisions in the camp, prisoners found ways to support each other. Sick and injured prisoners were given clandestine food as well as medicine and sanitary supplies stolen from the camp pharmacy. Healthy prisoners were expected to cover for sick prisoners who would otherwise be killed. The camp nurse Kurt Ticho developed a method of falsifying his records so that sick prisoners could take more than the allotted three day recovery period. Members of the railway brigade attempted to warn new arrivals of their impending murder but were met with incredulity. The most successful act of solidarity in the camp was the revolt on 14 October 1943, which was expressly planned so that all of the prisoners in the camp would have at least some chance of escape.