Many industrialized nations have increased their capacity for solar energy by increasing their energy consumption. Long distance transmission allows remote renewable energy resources to displace fossil fuel consumption. Solar power plants use one of two technologies:
A solar cell, or photovoltaic cell (PV), is a device that converts light into an electric current using the photovoltaic effect. The first solar cell was constructed by Charles Fritts in the 1880s. The German industrialist Ernst Werner von Siemens was the one who recognized the importance of this discovery. In 1931, the German engineer Bruno Lange developed a photo cell using silver selenide in place of copper oxide, the prototype selenium cells converted less than 1% of incident light into electricity. Following the work of Russell Ohl in the 1940s, Gerald Pearson, Calvin Fuller and Daryl Chapin researchers created the silicon solar cell in 1954. These early solar cells cost 286 USD / watt and reach efficiencies of 4.5-6%.
The array of a photovoltaic power system, or PV system, produces direct current (DC) power which fluctuates with the sunlight’s intensity. For practical use, this usually requires conversion to some desired voltages or alternating current (AC), through the use of inverters. Multiple solar cells are connected inside modules. Modules are wired together to form arrays, then tied to an inverter, which produces power at the desired voltage, and for AC, the desired frequency / phase. Many residential PV systems are connected to the grid where available, especially in developed countries with large markets. In these grid-connected PV systems, the use of energy storage is optional. In certain applications such as satellites, lighthouses, or in developing countries, batteries or additional power generators are often added as back-ups.
Concentrated solar power (CSP), also called “concentrated solar thermal”, then uses the resultant generation of steam-driven turbines. A wide range of concentrating technologies exists: among the best known are the parabolic trough, the compact linear Fresnel reflector, the Stirling dish and the solar power tower. Various techniques are used on the sun and focus light. In all of these systems, the sunlight is used, and is then used for power generation or energy storage. Thermal storage works up to 24-hour electricity generation. A parabolic trough consists of a linear parabolic reflector that concentrates light onto a storeroom along the reflector’s focal line. The receiver is one of the focal points of the linear parabolic mirror and is filled with a working fluid. The reflector is made to follow the day by tracking along a single axis. Parabolic trough systems provide the best The SEGS plants in California and Acciona’s Nevada Solar One near Boulder City, Nevada are representatives of this technology. Compact Linear Fresnel Reflectors are CSP-Plates that use many thin mirrors instead of parabolic mirrors to concentrate sunlight onto two tubes with working fluid. This is the advantage that can be used in other ways than other mirrors, and that it may be more important than other aspects of the environment. Concentrating linear fresnel reflectors can be used in large or larger compact plants. The Stirling Solar Dish combines a parabolic concentrating dish with a Stirling engine which normally drives an electric generator. The advantages of Stirling solar over photovoltaic cells are higher efficiency of converting sunlight into electricity and longer lifetime. Parabolic dish systems give the highest efficiency among CSP technologies. The 50 kW Big Dish in Canberra, Australia is an example of this technology. A solar power tower uses an array of tracking reflectors (heliostats) to concentrate light at a central receiver atop a tower. Power towers can achieve higher efficiency than linear tracking CSP schemes and better energy storage capability than dish stirling technologies.
The early development of solar technologies starting in the 1860s was driven by an expectation that coal would soon become scarce. Charles Fritts installed the world’s first rooftop photovoltaic solar array, using 1% -efficient selenium cells, a New York City roof in 1884. However, growth of solar technologies is stagnating in the early 20th century. and utility of coal and petroleum. In 1974 it was estimated that only six private homes in all of North America were fully heated or cooled by functional solar power systems. The 1973 oil embargo and the 1979 energy crisis caused a reorganization of energy policies around the world and brought renewed attention to developing solar technologies. Deployment strategies focused on incentive programs such as the Federal Photovoltaic Utilization Program in the US and the Sunshine Program in Japan. Other efforts included the formation of research facilities in the United States (SERI, now NREL), Japan (NEDO), and Germany (Fraunhofer-ISE). Between 1970 and 1983 installations of photovoltaic systems grew rapidly, but falling in the early 1980s moderated the growth of photovoltaics from 1984 to 1996.
In the mid-1990s, the development of both, residential and commercial rooftop solar energy and utility-scale photovoltaic power stations, global warming concerns, and the improving economic position of PV relative to other energy technologies. In the early 2000s, the adoption of feed-in tariffs-a policy mechanism, which gives renewed priority to the grid and a fixed price for the generated electricity-lead to a high level of investment and security. in Europe.
For several years, China and Japan, especially China and Japan, and others, but not limited to, Australia, Canada, Chile, India, Israel, Mexico, South Africa, South Korea, Thailand, and the United States. Worldwide growth of photovoltaics has reached 30% GW at the end of 2016 with China having the most cumulative facilities (78 GW) and Honduras having the highest rate of annual electricity usage be generated by solar PV (12.5%). The largest manufacturers are located in China. Concentrated solar power (CSP) also grew to increase rapidly, increasing its capacity almost tenfold from 2004 to 2013, albeit from a lower level and involving fewer countries than solar PV. As of the end of 2013, cumulative worldwide CSP-capacity reaches 3,425 MW.
In 2010, the International Energy Agency predicted that global solar PV capacity could reach 3,000 GW or 11% of global electricity generation by 2050-enough to generate 4,500 TWh of electricity. Four years later, in 2014, the agency projected that, under its “high renewables” scenario, solar power could supply 27% of global electricity generation by 2050 (16% from PV and 11% from CSP). In 2015, analysts predicted that one million homes in the US will have solar power by the end of 2016.
The Desert Sunlight Solar Farm is a 550 MW power plant in Riverside County, California, that uses thin-film CdTe-modules made by First Solar. As of November 2014, the 550 megawatt Topaz Solar Farm was the largest photovoltaic power plant in the world. This was surpassed by the 579 MW Solar Star complex. The current largest photovoltaic power station in the world is Longyangxia Dam Solar Park, in Gonghe County, Qinghai, China.
Commercial solar concentrating power (CSP) plants, also called “solar thermal power stations”, were first developed in the 1980s. The 377 MW Ivanpah Solar Power Facility, located in California’s Mojave Desert, is the world’s largest solar thermal power plant project. Other large CSP plants include the Solnova Solar Power Station (150 MW), the Andasol solar power station (150 MW), and the Extresol Solar Power Station (150 MW), all in Spain. The main advantage of CSP is the ability to efficiently add thermal storage, allowing the dispatching of electricity over a 24-hour period. As if on the whole day of the day, and many years ago CSP power plants use 3 to 5 hours of thermal storage.
The typical cost factors for solar power include the cost of the modules, wiring, inverters, labor cost, any land that may be required, the grid connection, maintenance and the solar insolation that will receive. Adjusting for inflation, it costs $ 96 per watt for a solar module in the mid-1970s. Process improvements and a very large boost in production have been shown to be down to 68 cents per watt in February 2016, according to Bloomberg New Energy Finance. Palo Alto, California, which is rated 3.7 cents per kilowatt hour. And in sunny Dubai large-scale solar generated electricity sold in 2016 for just 2.99 cents per kilowatt-hour – “competitive with any form of fossil-based electricity – and cheaper than most.” Photovoltaic systems use fuel and modules typically last 25 to 40 years. Thus, capital costs make up most of the cost of solar power. In the United States, solar panels are estimated to be 9 percent of the cost of photovoltaic electricity, and 17 percent of the cost of solar thermal electricity. Governments have created various financial incentives to encourage the use of solar power, such as feed-in tariff programs. In addition, Renewable portfolio standards requires a power of attorney to generate certain percentage of renewable energy. In most states, RPS can be achieved by any combination of solar, wind, biomass, landfill gas, ocean, geothermal, municipal solid waste, hydroelectric, hydrogen, or fuel cell technologies.
The PV industry is beginning to adopt the level of cost of electricity (LCOE) as the unit of cost. The electrical energy generated is sold in units of kilowatt hours (kWh). As a rule of thumb, and depending on the local insolation, 1 watt-peak of installed solar PV capacity is about 1 to 2 kWh of electricity per year. This corresponds to a capacity factor of around 10-20%. The product of the local cost of electricity and the insolation determines the break even point for solar power. The International Conference on Solar Photovoltaic Investments, organized by EPIA, has made it worthwhile for their investors in 8 to 12 years. As a result, since 2006 it has been economical for investors to install photovoltaic for free. Fifty percent of commercial systems in the United States were installed in 2007 and over 90% by 2009. Shi Zhengrong has said that, as of 2012, unsubsidized solar power is already competitive with fossil fuels in India, Hawaii, Italy and Spain . He said, “We are at a tipping point, and we are now starting to compete in the world without resources”. “Solar power will be able to compete against the power of the average power source in the world by 2015”. No longer are renewable power sources like solar and wind a luxury of the rich. They are now starting to compete in the real world without subsidies. “” Solar power will be able to compete in the world of power generation. No longer are renewable power sources like solar and wind a luxury of the rich. They are now starting to compete in the real world without subsidies. “” Solar power will be able to compete in the world of power generation.
In its 2014 edition of the Technology Roadmap: Solar Photovoltaic Energy Report, the International Energy Agency (IEA) published in 2013, for residential, commercial and utility-scale PV systems (see table below). However, DOE’s SunShot Initiative has reported much lower US installation prices. In 2014, prices continued to decline. The SunShot Initiative modeled US system prices from $ 1.80 to $ 3.29 per watt. Other sources identify similar prices range from $ 1.70 to $ 3.50 for different market segments in the US, and in the highly penetrated German market, prices for residential and small commercial rooftop systems of up to 100kW declined to $ 1.36 per watt (€ 1.24 / W By the end of 2014. In 2015, Deutsche Bank estimated costs for small residential rooftop systems in the US around $ 2. 90 per watt. Costs for utility-scale systems in China and India were estimated to be as low as $ 1.00 per watt.
Grid parity, the price of grid power, is more easily achieved than in Europe and Japan. In 2008, the levelized cost of electricity for solar PV was $ 0.25 / kWh or less in most of the OECD countries. By late 2011, the fully loaded cost was down to $ 0.15 / kWh for most of the OECD and to reach $ 0.10 / kWh in sunnier regions. These wind levels are the driving force behind vertical power supply companies, wind operators and wind turbine manufacturers. Grid parity was first achieved in Spain in 2013, Fossil fuel oil (diesel fuel) to produce electricity, and most of the US is expected to reach grid parity by 2015. In 2007, General Electric’s Chief Engineer predicted grid parity without subsidies in the United States by around 2015; other industries predicted an earlier date: the cost of solar grid power for the United States, and the growth of electricity prices.
The productivity of solar power in a region depends on solar irradiance, which varies by day and is influenced by latitude and climate. The locations with highest annual solar irradiance lie in the arid tropics and subtropics. Deserts lying in low latitudes usually have few clouds, and can receive sunshine for more than ten hours a day. These hot deserts form the Global Sun Belt circling the world. This belt consists of extensive swathes of land in Northern Africa, Southern Africa, Southwest Asia, Middle East, and Australia, as well as the much smaller deserts of North and South America. Africa’s eastern Sahara Desert, also known as the Libyan Desert, has been observed on the planet by NASA. Different measurements of solar irradiance (direct normal irradiance,
In cases of self-consumption of the solar energy, the payback time is calculated based on how much electricity is not purchased from the grid. For example, in Germany, with electricity prices of 0.25 € / kWh and insolation of 900 kWh / kW, one kWp will save € 225 per year, and with an installation cost of 1700 € / KWp the system cost will be returned in less than seven years. However, in many cases, the patterns of generation and consumption do not coincide, and some of the energy is fed back into the grid. The electricity is sold, and at other times when energy is taken from the grid, electricity is bought. The relative costs and prices obtained affect the economics. In many markets, the price paid for electricity is significantly lower than the price of electricity, which incentivizes self consumption. Moreover, separate self consumption incentives have been used in eg Germany and Italy. Grid interaction regulation has also included limitations of grid feed-in in some regions in Germany. By increasing self-consumption, the grid feed-in can be limited without curtailment, which wastes electricity. A good match between generation and consumption is key for high self consumption, and should be considered when deciding where to install solar power and how to size the installation. The match can be improved with batteries or controllable electricity consumption. However, batteries are expensive and require additional services. Hot water storage tanks with electric heating and heat pumps can provide low-cost storage for self-consumption of solar power. Shiftable loads, such as dishwashers, tumble dryers and washing machines, may provide controllable consumption only for limited users.
The political purpose of incentive policies is to facilitate the development of small and medium-sized enterprises. parity. The policies are implemented to promote national energy independence and high tech job creation and reduction of CO 2 emissions. Three incentive mechanisms are often used in the context of a renewable energy savings scheme, the Solar Power Renewable Energy Certificates (SRECs) )
With investment subsidies, the financial burden falls on the taxpayer, while with feed-in tariffs is distributed across the utilities’ customer bases. While the investment subsidy may be simpler to administer, the main argument in favor of feed-in tariffs is the encouragement of quality. Investment grants are paid out as a function of the nameplate capacity of the system and are independent of their actual power yield over time, thus rewarding the overstatement of power and tolerating poor durability and maintenance. Austin Energy in Texas, which offers $ 2.50 / watt installed up to $ 15,000.
In fact, the price of the electricity produced is the same as the price of the consumer, and the consumer is billed on the difference between production and consumption. Net metering can be done with a difference in electricity consumption, and it can be used to reduce electricity consumption. giant storage battery. With net metering, deficits are billed each month while surpluses are rolled over the following month. Best practices call for perpetual roll over of kWh credits. Excess credits on termination of service are either lost, or paid for, or may be excessively high.
With feed-in tariffs, the financial burden falls upon the consumer. They reward the number of kilowatt-hours produced over a long period of time, but the rate is set by the authorities, it can result in perceived overpayment. The price paid per kilowatt hour under a feed-in tariff exceeds the price of grid electricity. Net metering refers to the case where the price paid by the utility is the same as the price charged. The complexity of approvals in California, Spain and Italy has prevented comparable growth in Germany even though the return on investment is better. In some countries, additional incentives are offered for BIPV compared to stand alone PV.
Alternatively, SRECs allow for a market price mechanism of the solar generated electricity subsity. In this mechanism, a renewable energy production or consumption target is set, and the utility (more technically the Load Serving Entity) is obliged to purchase renewable energy or face a fine (Alternative Compliance Payment or ACP). The producer is credited for an SREC for every 1,000 kWh of electricity produced. If the utility buys this SREC and withdraws it, they avoid paying the ACP. In principle, this system offers the best renewable energy, since they are eligible and can be installed in the most economic locations. Uncertainties about the future value of SRECs and SRECs to pre-sell and hedge their credits. Financial incentives for photovoltaics differ across countries, including Australia, China, Germany, Israel, Japan, and the United States and even across states within the US.The Japanese government through its Ministry of International Trade and Industry ran a successful program of subsidies from 1994 to 2003. By the end of 2004, the world in the world PV capacity with over 1.1 GW. In 2004, the German government introduced the first large-scale feed-in tariff system under the German Renewable Energy Act, which resulted in explosive growth of PV facilities in Germany. At the outset the FIT was over 3x the retail price or 8x the industrial price. The principle behind the German system is a 20-year flat rate contract. The value of new contracts is programmed to decrease each year, in order to encourage the industry. The program has been more successful than expected with over 1GW installed in 2006, and political pressure is mounting to decrease the burden on consumers. Subsequently, Spain, Italy, Greece-that enjoyed an early success with domestic solar-thermal facilities and France introduced feed-in tariffs. None has decreased the FIT program in new contracts though, making the German incentive relatively less and less attractive compared to other countries. The French and Greek FIT offers a high premium (EUR 0.55 / kWh) for building integrated systems. California, Greece, France and Italy have 30-50% more insolation than Germany making them financially more attractive. The Greek domestic “solar roof” The program (adopted in June 2009 for installations up to 10 kW) has a higher rate of return for the future. In 2006 California approved the ‘California Solar Initiative’, offering a choice of investment grants or FIT for small and medium systems and FIT for large systems. The small-system FIT of $ 0.39 per kWh (expires less than EU countries) expires in just 5 years, and the alternate “EPBB” residential investment incentive is modest, averaging perhaps 20% of cost. All California incentives are scheduled to decrease in the future depending on the amount of PV capacity installed. At the end of 2006, the Ontario Power Authority (OPA, Canada) launched its Standard Offer Program, a precursor to the Green Energy Act, and the first in North America for distributed renewable projects of less than 10 MW. The feed-in price guaranteed a fixed price of $ 0.42 CDN per kWh over a period of twenty years. Unlike net metering, all the electricity has been sold to the OPA at the given rate.
The overwhelming majority of electricity production is usually used today. However, both solar power and wind power are variable renewable energy, which means that it can be used everywhere. Since solar energy is not available at night, energy conservation is important. Solar electricity is inherently variable and predictable by time of day, location, and seasons. In addition, solar is intermittent due to day / night cycles and unpredictable weather. How much of a special challenge? In a summer peak utility, solar is well matched to daytime cooling demand. In winter peak utilities, solar displaces other forms of generation, reducing their capacity factors. In an electricity system without grid energy storage, generation from stored fuels (coal, biomass, natural gas, nuclear) must be made up and down in response to the rise and fall of solar electricity. While hydroelectric and natural gas plants can quickly follow solar intermittent to the weather, coal, biomass and nuclear plants usually take a toll. Depending on local circumstances, after about 20-40% of total generation, grid-connected intermittent sources like solar tend to require investment in some combination of grid interconnections, energy storage or demand side management. Integrating large amounts of solar power with existing generation equipment. For example, in Germany, California, and Hawaii, the power of solar power has been raised. Conventional hydroelectricity works very well in conjunction with solar power, water can be held back or released from a reservoir behind a dam as required. Where a suitable river is not available, pumped-storage hydroelectricity uses solar power to pump water to a high reservoir on sunny days then the energy is recovered by a hydroelectric plant to a low reservoir where the cycle can begin again. However, this cycle can be expected to increase the cost of energy efficiency. Concentrated solar power plants may use thermal storage, such as high temperature molten salts. These are an effective storage medium because they are low-cost, have a high specific heat capacity, and can deliver heat at temperatures compatible with conventional power systems. This method of energy storage is used, for example, by the Solar Two power station, allowing it to store 1. 44 TJ in it 68 m3 storage tank, enough to provide full output for close hours, with an efficiency of about 99%. In stand alone PV systems batteries are traditionally used to store excess electricity. With grid-connected photovoltaic power system, excess electricity can be felt to the electrical grid. Net metering and feed-in tariff programs give these systems a credit for electricity they produce. This credit can not be effectively met with the grid, but with the grid instead of storing excess electricity. Credits are normally rolled over by monthly surplus. When wind and solar are a small fraction of the power grid, other generation techniques can adjust their output appropriately, additional balance on the grid is needed. Prices are rapidly declining, the most expensive batteries are used. Batteries used for grid-storage stabilizes the electrical grid by leveling out peaks usually for several minutes, and in rare cases for hours. In the future, they can charge a large share of the electricity grid, and they can charge them for electricity generation. Although not permitted under the US National Electric Code, it is technically possible to have a “plug and play” PV microinverter. A recent review article found that careful design system would enable such systems, but not all safety requirements. There are several companies selling solar systems available on the web, but there is a need for them to be more effective. Common battery technologies used in today’s PV systems include the lead-acid battery-modified battery-modified version of the lead-acid battery, nickel-cadmium and lithium-ion batteries. Lead-acid batteries are currently the predominant technology used in small-scale, residential PV systems, due to their high reliability, low self-discharge and maintenance costs, despite shorter lifetime and lower energy density. However, lithium-ion batteries have the potential to replace lead-acid batteries in the near future, Gigafactory 1. In addition, the Li-ion batteries of plug-in can be used in the future. vehicle-to-grid system. Since most vehicles are parked at an average of 95 percent of the time, their batteries could be used to generate electricity. Other rechargeable batteries used for distributed PV systems include, sodium-sulfur and vanadium redox batteries, two prominent types of a molten salt and a flow battery, respectively. The combination of wind and solar PV has the advantage that the two sources are at different times of the day and year. The power generation of such solar hybrid power systems is therefore more constant and fluctuates than each of the two component subsystems. Solar power is seasonal, particularly in northern / southern climates, from the equator, suggesting a need for a long-term storage of hydroelectricity. The Institute for Solar Energy Supply Technology of the University of Kassel pilot-tested a combined power plant linking solar, wind, biogas and hydrostorage to provide load-following power from renewable sources. Research is also undertaken in this field of artificial photosynthesis. It involves the use of nanotechnology to store solar electromagnetic energy in chemical bonds, by splitting water to produce hydrogen fuel or carbon dioxide to make biopolymers such as methanol. Many large national and regional research projects are being developed, and are currently being developed. Senior researchers in the field of public policy for a Global Project on Artificial Photosynthesis to address critical energy security and environmental sustainability issues.
Unlike fossil fuel based technologies, solar power does not lead to any harmful emissions during operation, but the production of the panels leads to some amount of pollution.
The life-cycle greenhouse-gas emissions of solar energy are in the range of 22 to 46 gram (g) per kilowatt-hour (kWh). With this potential being decreased to 15 g / kWh in the future. For comparison (of weighted averages), a combined cycle gas-fired power plant emits some 400-599 g / kWh, an oil-fired power plant 893 g / kWh, a coal-fired power plant 915-994 g / kWh or with carbon capture and storage some 200 g / kWh, and a geothermal high-temp. power plant 91-122 g / kWh. <ref name = “IPCC”> The life cycle emission intensity of hydro, wind and nuclear power are as follows IPCC, and discussed in the article Life Cycle greenhouse-gas emissions of energy sources. Similar to all energy sources were their total life cycle emissions primarily in the construction and transportation phases, the switch to low carbon power in the manufacturing and the transportation of carbon emissions. BP Solar owns two factories built by Solarex (one in Maryland, the other in Virginia) in which all of the energy used to manufacture solar panels is produced by solar panels. A 1-kilowatt system eliminates the burning of approximately 170 pounds of coal, 300 pounds of carbon dioxide from being released into the atmosphere, and saves up to 105 gallons of water consumption. The US National Renewable Energy Laboratory (NREL), in harmonizing the disparate estimates of life-cycle GHG emissions for solar PV, found that the most critical parameter was the solar insolation of the site: GHG emissions factors for solar PV are inversely proportional to insolation. For a site with insolation of 1700 kWh / m2 / year, typical of southern Europe, NREL. Using the same assumptions, at Phoenix, USA, with insolation of 2400 kWh / m2 / year, the GHG emissions factor would be reduced to 32 g of CO 2 e / kWh. The New Zealand Parliamentary Commissioner for the Environment found that the solar PV would have little impact on the country’s greenhouse gas emissions. The country already generated 80 percent of its electricity from renewable energy sources (mainly hydroelectricity and geothermal) and
The energy payback time (EPBT) of a power generating system is the time required to generate the energy consumption of the system. Due to improving production technologies the payback time has been decreasing constantly since the introduction of PV systems in the energy market. In 2000 the energy payback time of PV systems was estimated at 8 to 11 years and in these years it was estimated to be 1.5 to 3.5 years for crystalline silicon PV systems and 1-1.5 years for thin film technologies (S. Europe). These figures fell to 0.75-3.5 years in 2013, with an average of about 2 years for crystalline silicon PV and CIS systems. Another economic measure, closely related to the energy payback time, is the energy returned on energy (EROEI) or energy return on investment (EROI), which is the ratio of electricity generated by the energy required to build and maintain the equipment. (This is not the same as the economic return on investment (ROI), which varies according to local energy prices, subsidies and metering techniques.) With expected lifetimes of 30 years, the EROEI of PV systems are in the range of 10 30, thus generating sufficient energy on their lifetimes to reproduce themselves many times (6-31 reproductions), and the geographic location of the system.
Solar power includes plants with the lowest water consumption per unit of electricity (photovoltaic), and also power plants with among the highest water consumption (concentrating solar power with wet-cooling systems). Photovoltaic power plants use very little water for operations. Life-cycle water consumption for utility-scale operations is estimated to be 12 gallons per megawatt-hour for PV solar flat-panel. Only wind power, which does not have a lot of energy. Concentrating solar power plants with wet-cooling systems, on the other hand, have the highest water-consumption intensities of the conventional type of electric power plant; only fossil-fuel plants with carbon-capture and storage may have higher water intensities. A 2013 study showed that 810 g / MWhr for power tower plants and 890 gal / MWhr for trough plants. This was higher than the operational water consumption (with cooling towers) for nuclear (720 gal / MWhr), coal (530 gal / MWhr), or natural gas (210). A study conducted by the National Renewable Energy Laboratory was similar to the following: For power plants with cooling towers, water consumption was 865 gal / MWhr for CSP trough, 786 gal / MWhr for CSP tower, 687 gal / MWhr for coal, 672 gal / MWhr for nuclear, and 198 gal / MWhr for natural gas. The Solar Energy Industries Association noted that the Nevada Solar One trough CSP plant consumes 850 gal / MWhr. The issue of water consumption is heightened because CSP plants are often located in arid environments where water is scarce. In 2007, the US Congress directed the Department of Energy to report on ways to reduce water consumption by CSP. The subsequent report noted that CSP by 91 to 95 percent. A hybrid wet / dry cooling system could reduce water consumption by 32 to 58 percent. A 2015 report by NREL noted that of the 24 operating CSP power plants in the US, 4 used dry cooling systems. Ivanpah Solar Power Facility near Barstow, California, and the Genesis Solar Energy Project in Riverside County, California. Of 15 CSP projects under construction as of March 2015, 6 were wet systems, 7 were dry systems, 1 hybrid, and 1 unspecified. Although many older thermoelectric power plants with more water, they are more water-cooled than others, and they consume less water by evaporation. For instance, the average 36,350 gal / MWhr, but only 250 gal / MWhr is lost through evaporation. Since the 1970s, the majority of US power plants have used recirculating systems such as cooling towers rather than once-through systems. Although many older thermoelectric power plants with more water, they are more water-cooled than others, and they consume less water by evaporation. For instance, the average 36,350 gal / MWhr, but only 250 gal / MWhr is lost through evaporation. Since the 1970s, the majority of US power plants have used recirculating systems such as cooling towers rather than once-through systems. Although many older thermoelectric power plants with more water, they are more water-cooled than others, and they consume less water by evaporation. For instance, the average 36,350 gal / MWhr, but only 250 gal / MWhr is lost through evaporation. Since the 1970s, the majority of US power plants have used recirculating systems such as cooling towers rather than once-through systems. and they consume less water by evaporation. For instance, the average 36,350 gal / MWhr, but only 250 gal / MWhr is lost through evaporation. Since the 1970s, the majority of US power plants have used recirculating systems such as cooling towers rather than once-through systems. and they consume less water by evaporation. For instance, the average 36,350 gal / MWhr, but only 250 gal / MWhr is lost through evaporation. Since the 1970s, the majority of US power plants have used recirculating systems such as cooling towers rather than once-through systems.
One issue that has been raised is the use of cadmium (Cd), a toxic heavy metal that has the tendency to accumulate in ecological food chains. It is used as a semiconductor component in CdS cells and as a buffer for some CIGS cells in the form of CdS. The amount of cadmium used in thin-film PV modules is relatively small (5-10 g / m²) and with proper recycling and emission control techniques in place the cadmium emissions from module production can be almost zero. Current PV technologies lead to cadmium emissions of 0.3-0.9 microgram / kWh over the whole life cycle. Most of these emissions arise from the use of lignite combustion and lead to much higher emissions of cadmium. Life-cycle cadmium emissions from coal is 3.1 microgram / kWh, lignite 6.2, and natural gas 0. 2 microgram / kWh. In a life-cycle analysis it has been noted that electricity produced by photovoltaic panels was used instead of the modules instead of electricity from combustion coal, cadmium emissions from coal power usage in the manufacturing process could be entirely eliminated. In the case of crystalline silicon modules, the solder material, contains about 36 percent of lead (Pb). Moreover, the paste used for screen printing contains a trace of Pb and sometimes Cd as well. It is estimated that about 1,000 metric tons of Pb have been used for 100 gigawatts of c-Si solar modules. However, there is no fundamental need for lead in the solder alloy. Some media sources have reported that concentrated solar power plants have injured or killed large numbers of birds due to intense heat from the concentrated sunrays. This adverse effect does not apply to PV solar power plants, and some of the claims may have been overstated or exaggerated. A 2014-published life-cycle analysis of land use for various sources of electricity that the wide-scale implementation of solar and wind-downs reduce pollution-related environmental impacts. The study found that the land-use footprint, given in square meter-years per megawatt-hour (m 2 y / MWh), was lowest for wind, natural gas and rooftop PV, with 0.26, 0.49 and 0.59, respectively, and followed by utility-scale solar PV with 7.9. For CSP, the footprint was 9 and 14, using parabolic troughs and solar towers, respectively.
: Floatovoltaics are an emerging form of PV systems that float on the surface of irrigation canals, water reservoirs, quarry lakes, and tailing ponds. Several systems exist in France, India, Japan, Korea, the United Kingdom and the United States. These systems would need to be more widely used, and they would otherwise be lost through evaporation, and they would have a higher efficiency of solar energy conversion, as the panels were kept at a cooler temperature than they would be on land. Although not floating, other dual-use facilities with solar power include fisheries.