Photovoltaic power station
[11] The USA,[12] China,[13] India,[14] France,[15] Canada,[16] Australia,[17] and Italy,[18] among others, have also become major markets as shown on the list of photovoltaic power stations.
[19][20][21] The land area required for a desired power output varies depending on the location,[22] the efficiency of the solar panels,[23] the slope of the site,[24] and the type of mounting used.
[29] Even in cultivated areas, a significant proportion of the site of a solar farm can also be devoted to other productive uses, such as crop growing[30][31] or biodiversity.
A recent study found that the value of solar generated electricity coupled to shade-tolerant crop production created an over 30% increase in economic value from farms deploying agrivoltaic systems instead of conventional agriculture.
[53][54] A solar inverter converts the array's power output from DC to AC, and connection to the utility grid is made through a high voltage, three phase step up transformer of typically 10 kV and above.
[59] 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.
[61] To achieve this, arrays can be designed using two-axis trackers, capable of tracking the sun in its daily movement across the sky, and as its elevation changes throughout the year.
[4] A third approach achieves some of the output benefits of tracking, with a lesser penalty in terms of land area, capital and operating cost.
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.
[85] In some regions soiling, the accumulation of dust or organic material on the solar panels that blocks incident light, is a significant loss factor.
[93] Solar power plants are developed to deliver merchant electricity into the grid as an alternative to other renewable, fossil or nuclear generating stations.
[107] At each stage in the process, the developer will be able to update estimates of the anticipated performance and costs of the plant and the financial returns it should be able to deliver.
[108] Photovoltaic power stations occupy at least one hectare for each megawatt of rated output,[110] so require a substantial land area; which is subject to planning approval.
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.
[116] A major aspect of the O&M contract will be continuous monitoring of the performance of the plant and all of its primary subsystems,[117] which is normally undertaken remotely.
Some connection contracts allow the transmission system operator to curtail the output of a solar park, for example at times of low demand or high availability of other generators.
[128] In recent years, PV technology has improved its electricity generating efficiency, reduced the installation cost per watt as well as its energy payback time (EPBT).
The subsidies and incentives, which were needed to stimulate the early market as detailed below, were progressively replaced by auctions[132] and competitive tendering leading to further price reductions.
The improving competitiveness of utility-scale solar became more visible as countries and energy utilities introduced auctions[133] for new generating capacity.
Amongst the prices quoted are: Solar generating stations have become progressively cheaper in recent years, and this trend is expected to continue.
[147] Prices for installed PV systems show regional variations, more than solar cells and panels, which tend to be global commodities.
[148] In the years before grid parity had been reached in many parts of the world, solar generating stations needed some form of financial incentive to compete for the supply of electricity.
[150] Feed-in tariffs are designated prices which must be paid by utility companies for each kilowatt hour of renewable electricity produced by qualifying generators and fed into the grid.
[151] These tariffs normally represent a premium on wholesale electricity prices and offer a guaranteed revenue stream to help the power producer finance the project.
[157] Another form of indirect incentive which has been used to stimulate investment in solar power plant was tax credits available to investors.
[162] The Clean Development Mechanism[163] of the UNFCCC is an international programme under which solar generating stations in certain qualifying countries can be supported.
[182] But it was the revisions to the German feed-in tariffs in 2004,[7] which gave the strongest impetus to the establishment of utility-scale solar power plants.
The EEG, the law which establishes Germany's feed-in tariffs, provides the legislative basis not just for the compensation levels, but other regulatory factors, such as priority access to the grid.
[192] Italy has a large number of photovoltaic power plants, the largest of which is the 84 MW Montalto di Castro project.
[195][needs update] The majority of the deployment of solar power stations in Spain to date occurred during the boom market of 2007–8.
