A photovoltaic power station , also known as a solar park , is a large-scale photovoltaic system (PV system) designed for the supply of merchant power into the electricity grid . They are differentiated from solar power applications because they supply power to the utility level, rather than to a local user or users. They are sometimes referred to as solar farms or solar ranches , especially when sited in agricultural areas. The generic expression utility-scale is sometimes used to describe this type of project.
The solar power source is via photovoltaic modules that convert light directly to electricity. However, this differs from, and should not be confused with, concentrated solar power , the other large-scale solar generation technology. Both approaches have their own advantages and disadvantages, but to date, for a variety of reasons, photovoltaic technology has seen a lot of use in the field. As of 2013 , PV systems outnumber concentrators by about 40 to 1.
In some countries, the nameplate capacity of a photovoltaic power station is rated in megawatt-peak (MW p ), which refers to the solar array’s DC power output. However, Canada, Japan, Spain and some parts of the United States often specify the lower nominal power output in MW AC ; a measure directly comparable to other forms of power generation. A third and less common rating is the mega volt-amperes (MVA). Most solar parks are developed at a scale of at least 1 MW p . As at the start of 2017, the world’s largestphotovoltaic power station has a capacity of over 800 megawattsand projects up to 1 gigawatt are planned. As of the end of 2016, about 4,300 projects with a combined capacity of 96 GW AC   were solar farms larger than 4 MW AC . 
Most of the existing large-scale photovoltaic power stations are owned and operated by independent power producers, but the involvement of community and utility-owned projects is increasing. To date Almost all-have-been supported at least in-part by regulatory incentives Such As feed-in tariffs or tax credits , purpose as levelized costs -have fallen Significantly in the last decade and grid parity has-been atteint in year Increasing number of markets, it may not be long before external incentives cease to exist.
The first 1 MW p solar park Was built by Arco Solar at Lugo near Hesperia, California at the end of 1982  Followed in 1984 by a 5.2 MW per facility in Carrizo Plain .  Both have since been decommissioned, though Carrizo Plain is the site for several large plants now being constructed  or planned. The next stage followed the 2004 revisions  to the feed-in tariffs in Germany  when a substantial volume of solar parks were constructed. 
Several hundred installations over 1 MW p -have-been-been installed since in Germany, more than 50 of qui are over 10 MW p .  With its introduction of feed-in tariffs in 2008, Spain has become the largest market, with some 60 solar parks over 10 MW,  but these incentives have since been withdrawn.  The USA,  China  India,  France,  Canada,  and Italy,  among others, have also become major markets as shown on the list of photovoltaic power stations .
The Largest site under construction-have Capacities of Hundreds of MW p and projects at a scale of 1 GW p are planned being white.   
Siting and land use
The Land Area Required for a Power Power Output,  and on the efficiency of the solar modules,  the slope of the site  and the type of mounting used. Fixed tilt solar arrays using typical modules of about 15% efficiency  on horizontal sites, need about 1 hectare / MW in the tropics and this figure rises to over 2 hectares in northern Europe. 
Because of the longer shadow the array when tilted at a steeper angle,  this area is typically about 10% higher for an adjustable tilt array or a single axis tracker, and 20% higher for a 2-axis tracker,  ] but these figures will vary depending on the latitude and topography. 
The best locations for land use are held to be brown fields, or where there is no other valuable land use.  Even in cultivated areas, a significant proportion of the site of a crop farm can also be devoted to other productive uses, such as crop growing   or biodiversity. 
Agrivoltaics is Co-Developing the Saami area of land for Both solar photovoltaic power as well as for conventional agriculture . A recent study found that the value of solar generated electricity combined with the production of agricultural production rather than the cost of farming. 
In some cases, several separate solar power stations, with separate owners and contractors, are developed on adjacent sites.  This can offer the advantage of the projects and the cost of the project.  Solar farms can also be co-located with wind farms.  Sometimes the title ‘solar park’ is used, rather than an individual solar power station.  
Some examples of such solar clusters are the Charanka Solar Park , where there are 17 different generation projects; Neuhardenberg,   with eleven plants, and the Golmud solar parks with total reported capacity over 500MW.   An extreme example of the Gujarat state of India has a single solar park, the Gujarat Solar Park .
Most Solar parks are grounded PV systems, also known as free-field solar power plants.  They can be used for a single or dual axis solar tracker .  While tracking improves the overall performance, it also increases the system’s installation and maintenance cost.   A solar inverter converts the array’s power output from DC to AC , and is connected to the utility grid is made through a high voltage, three phase step up transformer of typically 10 kV and above.  
Solar array arrangements
The solar arrays are the subsystems which convert incoming light into electrical energy.  They include a multitude of solar modules , mounted on support structures and interconnected to deliver a power output to electronic power conditioning subsystems. 
A minority of utility-scale solar arrays are configured on buildings  and are used for building-mounted solar arrays. The majority are ‘free-field’ systems using ground-mounted structures,  usually of one of the following types:
Many projects use mounting structures where the solar modules are mounted at a fixed inclination calculated to provide the optimum annual output profile. The modules are normally oriented towards the Equator, at a tilt angle slightly less than the latitude of the site. In some cases, depending on local climatic, topographical or electricity pricing regimes, different tilt angles can be used, or the arrays might be offset from the normal East-West axis to favour morning or evening output.
A variant on this design is the use of arrays, whose tilt angle can be adjusted twice or four times annually to optimise seasonal output. They also require more land area to reduce internal shading at the steeper winter tilt angle.Because the increased output is typically only a few percent, it seldom justifies the increased cost and complexity of this design.
Dual axis trackers
To maximise the intensity of incoming direct radiation, solar panels should be orientated normal to the sun’s rays. To achieve this, arrays can be designed using two-axis trackers, capable of tracking the sun in its daily orbit across the sky, and as its elevation changes throughout the year.
These arrays need to be spaced out to reduce inter-shading as the sun moves and the array orientations change, so need more land area. They also require more complex mechanisms to maintain the array surface at the required angle. The increased output can be of the order of 30% in locations with high levels of direct radiation, but the increase is lower in temperate climates or those with more significant diffuse radiation, due to overcast conditions. For this reason, dual axis trackers are most commonly used in subtropical regions, and were first deployed at utility scale at the Lugo plant.
Single axis trackers
A third approach achieves some of the output benefits of tracking, with a lesser penalty in terms of land area, capital and operating cost. This involves tracking the sun in one dimension – in its daily journey across the sky – but not adjusting for the seasons. The angle of the axis is normally horizontal, though some, such as the solar park at Nellis Airforce Base, which have a 20° tilt, incline the axis towards the equator in a north-south orientation – effectively a hybrid between tracking and fixed tilt.
Single axis tracking systems are aligned along axes roughly North-South. Some use linkages between rows so that the same actuator can adjust the angle of several rows at once.
Solar panels produce direct current (DC) electricity, so solar parks need conversion equipment to convert this to alternating current (AC), which is the form transmitted by the electricity grid. This conversion is done by inverters. To maximise their efficiency, solar power plants also incorporate maximum power point trackers, either within the inverters or as separate units. These devices keep each solar array string close to its peak power point.
There are two primary alternatives for configuring this conversion equipment; centralised and string inverters, although in some cases individual, or micro-inverters are used. Single inverters allows optimizing the output of each panel, and multiple inverters increases the reliability by limiting the loss of output when an inverter fails.
These units have relatively high capacity, typically of the order of 1 MW, so they condition that the output of a substantial block of solar arrays, up to perhaps 2 hectares (4.9 acres) in area. Solar parks using centralised inverters are often configured in discrete rectangular blocks, with the related inverter in one corner, or the centre of the block.
String inverters are substantially lower in capacity, of the order of 10 kW, and condition the output of a single array string. This is normally a whole, or part of, a row of solar arrays within the overall plant. String inverters can enhance the efficiency of solar parks, where different parts of the array are experiencing different levels of insolation, for example where arranged at different orientations, or closely packed to minimise site area.
The system inverters typically provide power output at voltages of the order of 480 VAC. Electricity grids operate at much higher voltages of the order of tens or hundreds of thousands of volts, so transformers are incorporated to deliver the required output to the grid. Due to the long lead time, the Long Island Solar Farm chose to keep a spare transformer onsite, as transformer failure would have kept the solar farm offline for a long period. Transformers typically have a life of 25 to 75 years, and normally do not require replacement during the life of a photovoltaic power station.
The performance of a solar park is a function of the climatic conditions, the equipment used and the system configuration. The primary energy input is the global light irradiance in the plane of the solar arrays, and this in turn is a combination of the direct and the diffuse radiation. 
A key determinant of the output of the system is the conversion efficiency of the solar modules, which will depend in particular on the type of solar cell used. 
AC power output to the grid, due to a wide range of factors such as light absorption losses, mismatch, cable voltage drop, conversion efficiencies, and other parasitic losses.  A parameter called the ‘performance ratio’  has been developed to evaluate the total value of these losses. The performance ratio gives a measure of the output AC power delivered as a proportion of the total DC power which the solar modules should be able to deliver under the ambient climatic conditions. In modern solar parks the performance ratio should typically be in excess of 80%.  
Early photovoltaic systems output decreased as much as 10% / year,  but as of 2010 the median degradation rate was 0.5% / year, with modules made after 2000 having a significant lower degradation rate, so that a system would lose only 12 % of its output performance in 25 years. A system using modules which degrades 4% / year will lose 64% of its output during the same period.  Many panel makers offer a performance guarantee, typically 90% in ten years and 80% over 25 years. The output of all panels is typically more than 3% during the first year of operation. 
The business of developing solar parks
Solar power plants are being developed to deliver electricity to the grid as an alternative to other renewable, fossil or nuclear generating stations. 
The plant owner is an electricity generator. Most solar power plants are owned by independent power producers (IPP’s),  although some are held by investor- or community-owned utilities. 
Some of These power producteurs Develop Their Own portfolio of power plants,  goal MOST solar parks are designed and constructed INITIALLY by specialist project developers.  Typically the developer will get the plan, get the planning and the connection, and arrange financing for the capital required.  The actual building work is contracted to Normally one more gold EPC (engineering, procurement and construction) contractors. 
Major milestones in the development of a new photovoltaic power plant are planning consent,  grid connection approval,  financial close,  construction,  connection and commissioning.  At each stage in the process, the developer should be able to meet expectations of the future performance and costs of the plant and the financial returns it should be able to deliver. 
Photovoltaic power stations occupy at least one hectare for each megawatt of rated output,  so require a substantial land area; which is subject to planning approval. The chances of obtaining consent, and the related time, cost and conditions, varying from jurisdiction to jurisdiction and location to location. Many planning approvals will also apply in the future.  A professional health, safety and environment assessment is usually established during the design of a power station and is subject to all HSE regulations.
The availability, locality and capacity of the connection to the grid is a major consideration in planning a new solar park, and can be a significant contributor to the cost. 
Most stations are located within a few kilometers of a suitable grid connection point. This network needs to be capable of absorbing the output of the solar park when operating at its maximum capacity. The project developer will normally be able to use the same method as the other. In addition, the grid may be accommodated by the grid. 
Operation and maintenance
Once the solar park has been commissioned, the owner usually enters into a contract with a suitable counterparty to undertake operation and maintenance (O & M).  In many cases this may be fulfilled by the original EPC contractor. 
Solar plants’ reliable solid-state systems require minimal maintenance, compared to rotating machinery for example.  A major aspect of the O & M contract will be the continuous monitoring of the performance of the plant and all of its primary subsystems,  which is normally undertaken remotely.  This allows performance to be compared with the anticipated output under the climatic conditions.  It also provides data to enable the scheduling of both rectification and preventive maintenance.  A small number of large solar farms use a separate inverter   or maximizer for each solar panel, which can be monitored. For other solar farms, thermal imaging is a tool that is used to identify non-performing panels for replacement. 
A solar park is derived from the sales of electricity to the grid, and its output is metered in real-time with readings of its energy output provided, typically on a half-hourly basis, for balancing and settlement within the electricity market. 
Income is affected by the reliability of equipment within the framework of the availability of the grid network to which it is exporting.  Some links contracts allow the transmission system operator to constrain the output of a solar park, for example at times of low demand or high availability of other generators.  Some countries make provision for grid access  for renewable generators, such as under the European Renewable Energy Directive . 
Economics and Finance
In recent years, PV technology Improved HAS icts Electricity Generating efficiency , reduced the system cost per watt as well as ict energy payback time (PLTS) and HAS atteint grid parity in at least 19 different markets by 2014.   Photovoltaics is becoming a viable source of mainstream power.  However, prices for PV systems show strong regional variations, much more than solar cells and panels, which tend to be global commodities. In 2013, China and Germany were significantly lower ($ 1.40 / W) than in the United States ($ 3.30 / W). The IEAexplains these discrepancies in “soft costs”, which includes customer acquisition, permitting, inspection and interconnection, installation labor and financing costs.  : 14
|Country||Cost ($ / W)|
|For utility-scale PV systems in 2013  : 15|
Solar generating stations have become progressively cheaper in recent years, and this trend is expected to continue. Meanwhile, traditional electricity generation is becoming progressively more expensive. These trends are expected to lead to a crossover point when the levelised cost of energy from solar parks, historically more expensive, matches the cost of traditional electricity generation. This point is commonly referred to as grid parity.
For merchant solar power stations, where the electricity is being sold into the electricity transmission network, the levelised cost of solar energy will need to match the wholesale electricity price. This point is sometimes called ‘wholesale grid parity’ or ‘busbar parity’.
Some photovoltaic systems, such as rooftop installations, can supply power directly to an electricity user. In these cases, the installation can be competitive when the output costs the country at which the user pays for his electricity consumption. This situation is sometimes called ‘retail grid parity’, ‘socket parity’ or ‘dynamic grid parity’.  Research the carried out by UN-Energy in 2012 Suggests areas of sunny countries with high electricity prices, Such As Italy, Spain and Australia, and areas using diesel generators, atteint-have retail grid parity. 
The Because the… Because. Because. Because. Because. Because.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,. Because. Because. Because. Because. Because. Because. Because..  Many legislatures around the world have introduced such incentives to support the deployment of solar power stations. 
Feed-in tariffs for each kilowatt hour of renewable electricity produced by qualified generators and fed into the grid.  These tariffs represent a guaranteed rate of return to the world of production. 
Renewable portfolio standards and obligations
These standards are obligations on utility companies to source a proportion of their electricity from renewable generators.  In most cases, they should not use which technology should be used and the most appropriate renewable sources. 
There are some exceptions where solar technologies are allocated to the proportion of the RPS in what is sometimes referred to as a ‘solar set aside’. 
Loan guarantees and other capital incentives
Some countries and states adopt a limited range of financial incentives, available for a wide range of infrastructure investment, such as the US Department of Energy Loan Guarantee Scheme,  which stimulated a number of investments in the solar power plant in 2010 and 2011. [ 135]
Tax credits and other fiscal incentives
Another form of indirect incentive that has been used to encourage investors to invest in their investments. In some cases the credits were linked to the energy produced by the facilities, such as the Production Tax Credits.  In other cases the credits were related to the capital investment such as the Investment Tax Credits 
International, national and regional programs
In addition to free market commercial incentives, some countries and regions have specific programs to support the deployment of solar energy installations.
The European Union ‘s Renewables Directive  sets targets for Increasing levels of deployment of renewable energy in all member states. The National Renewable Energy Action Plan provides a framework for the development of renewable energy.  The directive also permits states to develop their international boundaries, and this may lead to bilateral programs such as the Helios project. 
The Clean Development Mechanism  of the UNFCCC is an international program under which solar generating stations in certain countries can be supported. 
Many other countries have specific solar energy development programs. Some examples are India ‘s JNNSM ,  the Flagship Program in Australia ,  and similar projects in South Africa  and Israel . 
The financial performance of the solar power plant is a function of its income and its costs. 
The electrical output of a solar park will be related to solar radiation, the capacity of the plant and its performance ratio.  The income derived from this electricity output of the electricity market,  and any incentive payments such as those under the terms of the Tariffs or other support mechanisms. 
Electricity prices can vary at different times of day, giving a higher price at times of high demand.  This may influence the design of the plant to increase its output at such times. 
The dominant costs of solar power plants are the capital cost, and therefore any associated financing and depreciation.  Though operating costs are Typically Relatively Low, Especially as no fuel is required,  MOST operators will want to Ensure That adequate operation and maintenance cover  is available to maximize the availability of the plant and thereby maximizes the income to cost ratio. 
The first places to reach grid parity were with high levels of solar radiation.  Currently, more capacity being white is installed in the rooftop than in the utility-scale segment. However, the worldwide distribution of solar parks is expected to change the grid.  This transition aussi includes a shift from rooftop Towards utility-scale plants, since the focus of new PV deployment Has Changed from Europe Reviews towards the Sunbelt markets Where ground-mounted PV systems are Favored.  : 43
Because of the economic background, large-scale systems are presently distributed where the support schemes have been most consistent, or the most advantageous.  Total capacity of worldwide PV plants above 4 MW AC was assessed by Wiki-Solar as 36 GW in c. 2,300 installations at the end of 2014  and represents 25 percent of total global capacity of 139 GW.  : 17 The countries which had the most capacity, in descending order, were the United States , China , Germany , India , United Kingdom , Spain , Italy, Canada and South Africa .  Activities in the key markets
China has been reported in early 2013 to have overtaken Germany as the nation with the most utility-scale solar capacity.  Much of this has been supported by the Clean Development Mechanism .  The distribution of power plants in the Gobi desert  and connected to the Northwest China Power Grid. 
The first multi-megawatt plant in Europe was the 4.2 MW community-owned project at Hemau, commissioned in 2003.  But it was the revisions to the German feed-in tariffs in 2004,  which gave the strongest impetus to the establishment of utility-scale solar power plants.  The first to be completed under this program was the Leipziger Land solar park developed by Geosol.  Several dozen plants were built between 2004 and 2011, several of which were at the time the largest in the world . The EEGThe law which establishes Germany’s feed-in tariffs, provides the legislative basis for the compensation, but other regulatory factors, such as priority access to the grid. The law has been amended in 2010 to restrict the use of agricultural land,  since which time has most developed its so-called ‘development land’, such as forming military sites.  Partly for this reason, the geographical distribution of photovoltaic power plants in Germany  is biased towards the former Eastern Germany.   As of February 2012, Germany had 1.1 million photovoltaic power plants. 
India has been rising up the leading nations for the installation of utility-scale solar capacity.  The Charanka Solar Park in Gujarat was officially opened in April 2012  and was at the time the largest group of solar power plantsin the world. Geographically the majority of the resorts are located in Gujarat and Maharashtra .  Rajasthan has successfully been attempting to attract solar development.  Rajasthan and Gujarat share the Thar Desert , along with Pakistan.
Italy has a very large number of photovoltaic power plants, the largest of which is the 84 MW Montalto di Castro project . 
The majority of the deployment of solar power stations in Spain to date during the boom market of 2007-8.  The stations are well distributed around the country, with some concentration in Extremadura , Castile-La Mancha and Murcia . 
The introduction of Feed-in tariffs in the United Kingdom in 2010 stimulated the first wave of utility-scale projects,  with c. 20 plants being completed  before tariffs were reduced on 1 August 2011 following the ‘Fast Track Review’.  A second wave of installations was undertaken under the UK’s Renewables Obligation , with the total number of plants reaching the end of March 2013 reaching 86.  This is reported to have made the UK Europe’s best market in the first quarter. of 2013. 
UK projects were originally concentrated in South West, but more recently spread across the South of England and into East Anglia and the Midlands.  The first solar park in Wales came on stream in 2011 at Rhosygilwen , North Pembrokeshire .  As of June 2014 there have been 18 more than 5 MW and 34 in planning or construction in Wales. 
The US deployment of photovoltaic power stations in southwestern states.  The Renewable Portfolio Standards in California  and surrounding states   Provide a Particular incentives. The volume of projects under construction in early 2013 will have become more important. 
Noteworthy solar parks
The following solar parks were, at the time they became operational, the largest in the world or their continent, or are notable for the reasons given:
|name||Country ||Nominal power
( MW )  
|Lugo,  San Bernardino County, California||USA||1 MW||Dec 1982||First MW plant|
|Carrisa Plain ||USA||5.6 MW||Dec 1985||World’s largest at the time|
|Hemau ||germany||4.0 MW||Apr 2003||Europe’s largest community-owned facility  at the time|
|Leipziger Land ||germany||4.2 MW||Aug 2004||Europe’s largest at the time; first under FITs  |
|Pocking ||germany||10 MW||Apr 2006||Briefly the world’s largest|
|Nellis Air Force Base, Nevada ||USA||14 MW||Dec 2007||America’s largest at the time|
|Olmedilla ||Spain||60 MW||Jul 2008||World’s largest Europe at the time|
|Sinan ||Korea||24 MW||Aug 2008||Asia’s largest at the time|
|Waldpolenz, Saxony ||germany||40 MW||Dec 2008||World’s largest thin film plant. Extended to 52 MW in 2011 |
|DeSoto, Florida ||USA||25 MW||Oct 2009||America’s largest at the time|
|The Roseraye ||Meeting||11 MW||Apr 2010||Africa’s first 10 MW + plant|
|Sarnia, Ontario ||Canada||97 MW P||Sep 2010||World’s largest at the time. Corresponds to 80 MW AC .|
|Golmud, Qinghai , ||china||200 MW||Oct 2011||World’s largest at the time|
|Finow Tower ||germany||85 MW||Dec 2011||Extension takes it to Europe’s largest|
|Lopburi ||thailand||73 MW||Dec 2011||Asia’s largest (outside of China)  at the time|
|Perovo, Crimea ||Ukraine||100 MW||Dec 2011||Becomes Europe’s largest|
|Charanka, Gujarat  ||india||221 MW||Apr 2012||Asia’s largest solar park|
|Agua Caliente, Arizona ||USA||290 MW AC||Jul 2012||World’s largest solar plant at the time|
|Neuhardenberg, Brandenburg ||germany||145 MW||Sep 2012||Becomes Europe’s largest solar cluster|
|Greenhough River, Western Australia , ||australia||10 MW||Oct 2012||Australasia’s first 10 MW + plant|
|Majes and Repartición||peru||22 MW||Oct 2012||First utility-scale seedlings in South America  |
|Westmill Solar Park , Oxfordshire||United Kingdom||5 MW||Oct 2012||Acquired by Westmill Solar Co-operative to become the world’s largest community-owned solar power station |
|San Miguel Power, Colorado||USA||1.1 MW||Dec 2012||Biggest community-owned plant in USA |
|Sheikh Zayed, Nouakchott ||mauritania||15 MW||Apr 2013||Largest solar power plant in Africa |
|Topaz ,  Riverside County, California||USA||550 MW AC||Nov 2013||World’s largest solar park at the time |
|Amanacer, Copiapó , Atacama||chile||93.7 MW||Jan 2014||Largest in South America  at the time|
|Jasper, Postmasburg , Northern Cape||South Africa||88 MW||Nov 2014||Largest plant in Africa|
|Longyangxia PV / Hydro power project, Gonghe , Qinghai||china||850 MW P||Dec 2014||Phase II of 530 MW added to 320 MW Phase I (2013)  makes this the world’s largest solar power station|
|Nyngan, New South Wales||australia||102 MW||Jun 2015||Becomes largest plant in Australasia and Oceania|
|Solar Star ,  Los Angeles County, California||USA||579 MW AC||Jun 2015||Becomes the world’s largest solar farm installation project|
|Cestas, Aquitaine||la France||300 MW||Dec 2015||Largest PV plant in Europe |
|Finished Terrae, Maria Elena,Tocopilla||chile||138 MW AC||May 2016||Becomes largest plant in South America |
|Solar II ||belarus||18.48MW||Apr 2016||Sobolee, Gomel’s Region|
|Monte Plata Solar, Monte Plata||Dominican Republic||30 MW||March 2016||Largest PV plant in The Caribbean.  |
Solar power plants under development are not included here, but may be on this list .