Photovoltaics

Photovoltaics is the direct conversion of light energy, usually from sunlight into electrical energy using solar cells. Since 1958 it has been used in space ( " awning "). Nowadays it is mainly used to generate electricity on Earth and finds, among other application on roofs, parking meters, in calculators, to soundproof walls and open spaces.

The term derives from the Greek word for " light " ( φῶς, phosphorus, in the genitive: φωτός, photos ) and from the unit of electrical voltage, the volt ( after Alessandro Volta ) from. Photovoltaics is a part of the field of solar technology, which includes further technical uses of solar energy.

The end of 2013 more than 134 GWp rated power were installed worldwide, which could with some 160 TWh annual production cover 0.85 % of global electricity demand. In Europe, the Photovoltaic covered 3% of total electricity demand and 6% of the peak load demand. Leader was Italy with a share of 7.8% in electricity consumption.

• 2.1 rated output and income
• 2.2 Mounting systems for roofs

• 6.1 Performance Ratio
• 6.2 Pollution and Cleaning
• 6.3 Energy payback

• 8.1 variation of the offer
• 8.2 transmission
• 8.3 Energy Storage 8.3.1 stand-alone system
• 8.3.2 composite system

• 9.1 Germany 9.1.1 funding
• 9.1.2 Tax treatment

History of photovoltaics

The photoelectric effect was discovered in 1839 by the French physicist Alexandre Edmond Becquerel. In 1954 it was possible to produce the first silicon solar cells with efficiencies of over 4%. The first industrial application in 1955 found in the power supply of telephone amplifiers. Since the late 1950s, photovoltaic cells are used in satellite technology: As the first satellite with solar cells Vanguard 1 was launched on March 17, 1958 in orbit. In the 1960s and 1970s, the demand from the aerospace industry has led to advances in the development of photovoltaic cells.

Triggered by the energy crises in the 1970s (oil crisis ) and increased environmental awareness will increase its focus on trying to make the development of this energy converter through technical progress and funding of the policy also economically interesting.

Spelling

Usually, the letters and the abbreviation photovoltaic PV is applied. Since the German spelling reform (in 2006 ) the spelling of photovoltaics is the new main form and photovoltaic continued permissible alternative spelling. In German -speaking countries the alternative spelling Photovoltaics is the common variant. For technical disciplines is always the spelling in standardization ( here also photovoltaics) is an essential criterion for the applicable notation. Internationally, the spellings are PV ( EU area ) and Ph (English photovoltaics ) in addition to other variants in use.

Technical Basics

For the energy conversion of the photoelectric effect of solar cells is exploited, which are connected to so-called solar modules. The electricity generated can be used directly, stored in batteries or fed into power grids. Before being fed into the AC power grids, the generated DC voltage is converted by an inverter. The system of solar panels and other components (inverters, power line ) is called the photovoltaic system or solar generator.

Rated output and income

The power rating of photovoltaic systems is often provided in the notation Wp (Watt peak) or kWp refers to the performance test conditions that correspond approximately to the maximum solar radiation in Germany. The test conditions are used for normalization and comparison of various solar modules. The electrical values ​​of the components are given in the data sheets. It is measured at 25 ° C module temperature, 1000 W / m² irradiance and air mass (abbreviated AM) of 1.5 measured. This standard test conditions ( STC usually abbreviated, Eng. Standard test conditions ) have been established as an international standard. If these conditions are not complied with during testing, it must be calculated from the given test conditions, the rated power.

The decisive factor for the dimensioning and the amortization of a photovoltaic system is in addition to the peak power, especially the annual yield, ie the amount of power gained. The radiant energy fluctuates daily, seasonal and weather conditions. Thus, a solar plant in Germany have one in July compared to December up to five times higher yield.

The yield per year is in watt-hours (Wh ) or kilowatt-hours ( kWh) measured. Location, orientation and shading of the modules have a significant influence on the yield, which deliver in Germany roof pitches of 30 ° the highest yield. The specific yield is ( / Wp Wh or kWh / kWp ) is defined as the watt-hours per installed nominal output per period of time, allowing easy comparison of plants of different sizes.

Mounting systems for roofs

When assembling systems distinguish between on-roof systems and roof systems. With a roof-mounted system for pitched roofs, the photovoltaic system is mounted using a mounting rack on the roof. This type of mounting is most often chosen because it is the easiest to implement on existing roofs.

In an in-roof system, a photovoltaic system is integrated into the roof and takes over its functions, such as roof leaks and weather protection.

The roof-mounted installation is next tile roofs for sheet metal roofs, slate roofs or corrugated sheets. If the roof pitch is too shallow, special hooks can compensate to some degree. The installation of a roof-mounted system is simpler and cheaper than that of an in-roof system generally. Also a roof-mounted system ensures sufficient ventilation of the solar modules. The necessary mounting materials must be weather resistant.

The roof system is suitable for roof renovations and new construction, but not all roofs possible. Tile roofs do not allow the roof installation, sheet metal roofing or asphalt roofs. The shape of the roof shall prevail. The roof installation is suitable only for sufficiently large pitched roofs with a favorable orientation to the sun path. Generally, in-roof systems put greater inclination angle advance as roof-mounted systems to allow adequate storm water runoff. In-roof systems form a closed surface with the rest of the roof covering and are therefore attractive from an aesthetic point of view. In addition, an in-roof system has a higher mechanical stability against wind and snow loads. The cooling of the modules is less efficient than in -roof system, which the performance and the yield decreased slightly. A higher temperature by 1 ° reduces the module output by about 0.5 %.

Worldwide utilization potential

The incident solar energy on the atmosphere is 1.5 × 1018 kWh per year; this corresponds to about 10,000 times the primary energy consumption of humanity in 2010 ( 1.4 × 1014 kWh / year). The light energy content is about 1.1 × 1018 per year kWh, but part of it is lost in the atmosphere. The incident on the earth's surface radiation energy can be converted into electrical energy without by-products such as exhaust fumes and carbon dioxide.

Near the equator, for example, in Chile, California, Australia or India, can be due to the high radiation density lower electricity production costs than in Central Europe achieve. Since in many countries there is no nationwide power grid, the photovoltaic can there produce electricity cheaper than eg a diesel generator.

An EU research project deals with the actual performance of photovoltaic vary by region. Meanwhile, there are several websites on the actual performance of photovoltaic can be determined for most areas of the world. The European Photovoltaic Industry Association (EPIA ) predicts an increase in global capacity by 2017 on an optimistic estimate of 423 GW, with conservative accounting to 288 GW. These projections made ​​on the basis of the data collected thus far for global installed PV capacity up to and including, 2012.

Paragraph development

Worldwide end of 2012 photovoltaic systems were installed with a capacity of approximately 101 GWp; the annex in 2012 amounted to about 30 GWp. In 2013 there were built about 39 GW worldwide, main market, with around 12 GW was China. Main market was in 2011 with an installed capacity of 24 875 MWp Germany, followed by Italy. Japan promotes the solar market through subsidies of about U.S. $ 9 billion in 2020 and will therefore reach 28 GWp. India has launched an ambitious expansion program and increased the installed capacity of 10 MWp in December 2010 at 1,040 MWp in July 2012. 2017 a further increase of 10 GWp in the country is expected.

Due to favorable manufacturing and temporary overcapacity large photovoltaic projects can be particularly cost-effective. This is thanks in particular to Chinese companies.

The construction of new facilities continues for several reasons:

• Module prices have dropped significantly
• The general level of prices for electricity balances at the state- subsidized prices
• Most countries in the world operate a low interest rate policy (see financial crisis from 2007); therefore investors prefer these low-risk investment option with relatively high yields.

The following tables provide an overview of the development of installed power rating of photovoltaic systems in the European Union in the years 2005 to 2012.

Photovoltaics in Germany

End of 2012, around 33 GW net electrical capacity were installed according to the Federal Network Agency. The consulting firm Roland Berger and the forecasters AG hold 2020 an expansion to 70 GW for realistic. Assuming that electrical energy could be stored without loss, would be to install a total of about 690 GW for an energy supply exclusively with photovoltaics at an average annual yield of 900 kWh per kWp. A full supply of electricity by the photovoltaic is due to the large diurnal and seasonal variations and the associated memory requirement in Germany is currently not technologically possible.

Efficiency

The efficiency is the ratio of currently generated electrical power to irradiated light output. The higher it is, the lower the surface can be maintained for the plant. In terms of efficiency it should be noted that system is considered ( single solar cell, solar panel or module, the entire system with inverter and charge controller and batteries and cabling). Some members are also dependent on the temperature. Thus, for solar cell may decrease the efficiency by up to 10% when the temperature rises by 25 °. Therefore, many systems do not reach the theoretical peak performance, which was calculated on the basis of laboratory tests in the summer. A combination of solar and thermal solar collector, which is commercially available since 2011, not only increasing the overall efficiency due to the additional thermal use, but also improves the electrical efficiency due to the cooling of the solar cells by thermal collectors. The actual efficiency is a measurement in Germany: The highest measured feed- was 23.05 GW reached on June 17, 2013, installed but were more than 32.5 GW. Thus, nearly 71 % of the rated power is reached.

The achievable with solar cell efficiencies are determined under standardized conditions. Organic solar cells achieve at present ( April 2011) up to 10.6 % efficiency, thin-film modules based on amorphous silicon is about 5 to 13 %, thin-film modules based on cadmium telluride about 13 %, of polycrystalline silicon solar cells 13 to 18 %, cells from monocrystalline silicon 14-24 %. So-called concentrator can achieve in laboratory situations over 40 % efficiency.

By the combination of cells of varying spectral sensitivity are disposed optically and electrically in series, in tandem, or Tripelschaltung efficiency was increased particularly in amorphous silicon. However, in such a series circuit limits always the cell with the lowest power the total current of the overall arrangement. Alternatively, the parallel connection of the solar cells arranged optically one after the other in dual switching thin film cells has been demonstrated for a-Si on the front glass and on the rear glass CIS.

With concentrator photovoltaic modules, the efficiency increases at higher light intensity, but they are necessarily dependent because of the concentration of light on tracking systems and can be used effectively as a rule only in areas with high direct sunlight.

Today's solar modules absorb a portion of the sunlight not but reflect it on their surface. Therefore, they are generally equipped with an anti- reflection layer, the already highly reduced reflection. Black silicon avoids these reflections almost completely.

Performance Ratio

The performance ratio (PR ) is the ratio between the actual user support and the target yield of a plant and is often called quality factor (Q). The " notional income " is calculated from the incident energy on the module surface (measured with a light sensor with the same orientation ) and the nominal module efficiency, so it refers to the amount of energy that the plant in operation under standard test conditions ( STC) and at 100 would reap % inverter efficiency. Real is the module efficiency and unshaded plants through heating, lower radiation, etc. compared to the STC under the nominal efficiency, also go by the nominal yield nor the line and inverter losses from. The target yield is thus a theoretical calculation value at STC. The performance ratio of a photovoltaic system should generally reach a value of at least 70 %. This value always refers to the average PR for an entire year. For example, the current PR is noon on cold days on average and decreases, especially at higher temperatures as well as morning and evening when the sun is flatter on the modules.

Pollution and cleaning

As with any outdoor surface (similar to windows, walls, roofs, automobiles, etc.) may also settle on photovoltaic systems different substances. These include, for example, leaves and needles, sticky organic secretions of aphids, pollen and seeds, soot from heaters and motors, sand, dust (eg including animal feed dusts from agriculture), growth of pioneer plants such as lichens, algae and mosses as well as bird droppings. The self-cleaning of the modules through rain and snow often is not enough to hold the investment for years or decades clean. This reduces the solar energy enters the module. The pollution acts as a shading and a yield loss is the result. This yield loss can be extreme dirt about 30%. The national average is assumed that a soil -related yield loss of 6-8%. In order to ensure consistent income, should have a wide range of systems checked regularly for dirt back and, if necessary, be cleaned. State of the art is the use of deionized water ( demineralized water) to avoid lime stains. As a further aid to come in cleaning water-bearing telescopic rods for use. Cleaning should be carried out gently to the module surface, eg not to damage through the use of abrasive cleaning equipment. In addition, modules should not and roofs are entered under the appropriate safety precautions. Even with a thermal imaging camera can detect the contamination. If a film of dirt on the modules, the modules are warmer and therefore they produce less electricity.

Energy payback

The Energy payback time of photovoltaic systems is the period in which the photovoltaic system has delivered the same amount of energy that is needed throughout their life cycle; for the manufacture, transport, erection, operation and dismantling and recycling.

She is currently (as of 2013) from 0.75 to 3.5 years, depending on location and used photovoltaic technology. The best- CdTe modules from 0.75 to 2.1, with values ​​of years, while modules made of amorphous silicon were up 1.8 to 3.5 years on average. Mono- and multi-crystalline systems, plants based on CIS were about 1.5 to 2.7 years. The life of 30 years for modules based on crystalline silicon cells and 20-25 years was assumed for thin-film modules in the study, for the life of the inverter 15 years were accepted.

When used in Germany is the energy that is required for the production of a photovoltaic system, won in solar cells in about two years. Of the yield factor is less than the typical irradiation conditions of Germany at least 10, a further improvement is unlikely. The life is estimated to be 20 to 30 years. The producers are given performance guarantees for 25 years for the modules normally. The energy-intensive part manufactured of solar cells can be 4 - to 5 - times be recycled.

Fields of application

In addition to electricity generation for grid feed-in Photovoltaics is also used for mobile applications and applications without connecting to a power grid, called off-grid systems are used. Here, the DC current can also be used directly. The most common, therefore, find battery-backed DC networks. In addition to satellite, solar vehicles or solar airplanes, which often relate their energy from solar cells, also everyday facilities such as cottages, solar lights, electric fencing, parking ticket machines or calculators are powered by solar cells. Grid systems with inverters can also supply AC loads.

Integration into the electricity grid

Fluctuation of the offer

• Statistics of production

Annual cycle in month presentation

The generation of solar power is subject to a typical daily and annual cycle, superimposed on by the weather. This can be predicted by weather observation (see Meteorology ).

Solar power can be used in particular in the summer to cover part of the medium load at noon. Even in summer, the generation of strong break (heavily overcast sky).

In winter, solar power can not be used to cover the medium load in the pole - proximal regions of the world, so in the winter sufficient capacity from other energy sources must be available. To compensate for the statistically predictable daily, weather and annual fluctuations, as well as storage options and switchable loads for consumption adjustment (smart switching in conjunction with smart metering ) are required.

Transmission

In a decentralized power supply by many small photovoltaic systems in the power range of some 10 kW transmission losses are reduced due to the small distances between source and load. The power generated leaves the low-voltage range virtually nonexistent, but is consumed to the producer. The operator of a domestic photovoltaic system supplies the extra power that he does not consume itself, into the low voltage network. This can be used by consumers directly adjacent. In the context of small systems an extension of the high voltage networks is therefore not necessary. Only after a further substantial expansion of photovoltaics incur regional surpluses, which would then be distributed geographically.

Energy Storage

For island installations and is converted into storage, usually batteries, buffered. The significantly more frequent composite systems feed power directly into the grid, where it is consumed immediately. Photovoltaic is a part of the electricity mix.

Stand-alone system

For island installations, the differences between consumption and power supply of the photovoltaic plant by energy storage must be compensated, for example, to operate at night or consumer or insufficient sunlight. Storage is usually a DC voltage intermediate circuit with batteries, consumers can supply if required. In addition to lead-acid batteries, newer battery technologies are used with improved efficiency such as lithium titanate batteries. By means of inverter can be generated from the intermediate circuit voltage, the usual AC mains voltage.

Find application grid systems, for example in remote areas, for which a direct connection to the public network is uneconomic. In addition, autonomous photovoltaic systems also allow the electrification of individual buildings ( such as schools or similar) or settlements in " developing countries ", in which no nationwide public power supply network is available.

Composite system

When investing in a power grid, the local energy storage can be eliminated, the balance of the different consumption and offer services via the grid. A caching is in principle only be superfluous if the current total supply of photovoltaic is always less than the current load. At high photovoltaic generation would then have the production of conventional power plants will be reduced, resulting in higher operating costs and lower efficiency of the power plants.

In smaller systems, all available or in excess of the self-consumption power is delivered into the grid. If it is missing ( eg at night), refer consumers their performance by other producers over the internetwork. For larger photovoltaic systems on a feed by remote control is required, with the help of which supply power can be reduced if the stability of the grid requires.

Since in a large grid fluctuations in consumption must be balanced in the short term, the storage of excess electrical energy in dedicated storage plants, such as occurs Pumped storage power plants. This store electrical energy in the form of potential energy with storage efficiencies of about 80% and can emit energy at peak demand in the short term in the grid. The attainable excellence depending on the size of the storage power plant in the range of several 100 MVA. This energy storage is gaining by the photovoltaic important, however, has long been the general power balance is used within an interconnected network. As pumped storage power plants can not be built locally, they require a developed electricity grid.

Accumulators in the form of larger plants in the interconnected system do not apply because of the high costs. The biggest -based batteries storage power plant in western European network with a storage capacity of 14.4 MWh and a peak power of 17 MVA was commissioned in 1994 in Berlin because of inefficiency out of service. The distributed caching in vehicle batteries (eg electric vehicles in car parks ) is due to lack of infrastructure usually not possible.

Other storage options include adiabatic working or heat latching air pressure power plants or the electrolysis of water and subsequent use of the resulting hydrogen in fuel cells, gas power plants or engines. These procedures are currently under development and / or they still have a low efficiency.

However, a large importance for renewable energy have intelligent networks that certain consumers (eg cooling systems, hot water heater, but also washing machines and dishwashers ) control so that they are switched on automatically when production peaks.

Security of supply

Despite the fluctuating supply of power from photovoltaic stands ( about 24 hours predicted in advance by weather forecasts ) more reliable available than that of a single large power plant. A failure or a planned shutdown of a major power plant has a stronger impact than the failure of a single photovoltaic system on the grid. If the number of photovoltaic systems results in a compared to a single large plant extremely high feed-in reliability.

In order to secure a default of major power generators, power plant operators must provide reserve power. This is not necessary with photovoltaics, since practically never are all PV systems simultaneously in revision or repair. With a high proportion of decentralized small-scale photovoltaic systems, however, a central controller of the load distribution throughout the network operator must take place.

During the cold wave in Europe in 2012, the photovoltaic grid- worked supportive. In January / February 2012, she fed a noon tip 1.3 to 10 GW. Due to the winter due to high power consumption had to import about 7-8 % of its electricity needs, while Germany, France exported.

State treatment

In several countries, the generation of electricity from photovoltaics is encouraged.

The feed-in tariff for solar energy in Germany is governed by the Renewable Energy Sources Act ( EEG), in Switzerland by the cost-covering remuneration. It is folded in Switzerland to all electricity consumers. In Germany, more than 2200 companies (as of September 16, 2013) are exempt from the payment of the EEG apportionment. The charge depends on:

• Year the start of operation: the sooner, the better
• Plant size: the smaller, the higher
• Type of installation: on houses higher than in open areas

Germany

In Germany there is a legally regulated feed-in tariff. Thus, a 30 - kWp system on a roof for the first time delivered energy in 2004, tempered with 57.4 ct / kWh. Due to the expansion of the photovoltaic subsidy rates were several times severely cut, most recently in March 2012 by 20-30 % (depending on system type). The development corridor for the years 2012 and 2013 are between 2.5 and 3.5 GW. If this maximum is exceeded, there would be further cuts. In systems that have been taken in the first half of 2011 in operation, the compensation amounts to only 28.74 ct / kWh. A ground-mounted system in 2009 will be paid with 31.94 ct / kWh, whereas plants from the first half of 2011, with 21.11 ct / kWh. 2011, the feed-in tariff for photovoltaic average of 40.16 ct / kWh, a total of about 7.77 billion euros.

→ see section " photovoltaic " under " Renewable Energy Law "

Programs

In addition to the feed-in tariff, there are twelve other programs to encourage the purchase of a photovoltaic system.

At the federal level, the so-called investment for photovoltaic plant in manufacturing and in the field of business services in the form of tax credits can be approved.

Besides, the KfW development bank, the following programs are available:

• KfW - renewable energy - Standard
• KfW - Kommunalkredit
• BMU - Demonstration program
• KfW - invest local.

The funds from the KfW development bank, in contrast to investment exclusively licensed as a loan and asked about the respective house bank.

Furthermore, have adopted the following states own solar promotion laws:

• Bavaria - efficient energy production and use in the business - ( grant)
• Lower Saxony - Innovation Funding ( Commercial ) - ( loan / grant in exceptions )
• North Rhine -Westphalia - progres.nrw " Rational use of energy, renewable energy and energy saving" - ( grant)
• Rhineland -Palatinate - energy efficient new buildings - ( grant)
• Saarland - future energy technology program ( ZEP -Tech ) 2007 ( Demonstrations-/Pilotvorhaben ) - ( grant).

A local support program offers the Upper Bavarian town of Burghausen 100 Wp installed with power up to max € 50.00. € 1,000.00 per plant and residential building

Tax Treatment

With an annual turnover of up to € 17,500 the small business regulation § 19 UStG applies, so no sales tax needs to be explained. In the case that the operator with the tax office as VAT taxable business, he also has the right to obtain a refund of the input tax on all investments. To the feed-in tariff, the sales tax will be paid extra, which is paid to the tax office.

For income derived from the photovoltaic system, § 15 Income Tax Act. Possible loss reduces the tax burden. The German tax authorities will recognize losses from the operation of the photovoltaic system will not turn on if there is a calculation based on looking at 20 years operating life of the plant, that the operation of the plant generates a total loss. Insofar as relevant rate of return calculation programs take into account a tax benefit, these issues must be considered.

Since an allowance of € 24,500 for natural persons and partnerships are for trade tax (§ 11 Paragraph 1 No. 1 TTA ), usually only large plants fall under the business tax.

Japan

One year after the nuclear disaster at Fukushima, the Japanese government has passed a law along the lines of the German EEG. From 1 July 2012, a feed-in tariff of 42 yen / kWh for photovoltaic plants with a capacity of ten kilowatts paid (converted about 0.36 € / kWh). This allowance is paid for 20 years. Smaller systems up to 10 kW only be funded for ten years.

Romania

The Romanian state awards 2011 green certificates, currently six certificates per 1000 kWh to 31 December 2013. Reducing the number of allowances is planned for 2014 under a law of November. The value of green certificates will be negotiated on the stock exchange and decreases with the quantity of electricity produced from renewable energy sources. In February 2012, the price was for a certificate to the equivalent of € 55, so that was paid for 1 kWh € 0.33. However, also fall to around half the price.

Economic viewing

Damping effect on the stock market electricity prices

PV is a supplier of peak load current, since it achieves the " top chef " at noon the highest yields, and displaces expensive gas - and coal-fired power plants from the market. Therefore, solar energy attenuates the exchange prices for peak current ( " merit order effect"). The peak electricity prices have fallen sharply in recent years in parallel with the development of solar energy compared to the average price. In summer, the previous daily peaks have largely disappeared. Because solar power pushes wholesale prices, to escape the corporations considerable revenue. The energy-intensive industries benefit: you can buy their electricity cheaper.

Reduction of external costs

Solar power causes less environmental damage than energy from fossil fuels or nuclear power, thus reducing the external costs of energy production.

In 2011, the cost of avoiding CO2 emissions by photovoltaic € 320 per avoided tonne of CO2 and were therefore more expensive than other renewable energy sources, modernize the conventional power plants or energy conservation measures ( insulation of buildings ), the cost of up to 45 € per tonne of CO2 cause or even generate cost savings.

How much CO2 emissions are actually avoided by photovoltaics, this also depends on the coordination of the EEG with the EU emissions trading scheme.

→ see section "Interaction with emissions trading " in " Renewable Energy Law "

End of 2011, the U.S. Nobel laureate economist Paul Krugman saw the photovoltaic module costs due to declining shortly before their competitiveness, especially if the external costs of fossil fuels are taken into account in the prices with. In February 2012, the Fraunhofer ISE documented that the continuously declining electricity generation costs for small photovoltaic systems (<10 kW) in the third quarter of 2011, with 24.67 ct / kWh have reached the price level of household electricity. Due to the recent price development, the ISE expects that the costs fall proportionately with the growth of installed capacity.

Value

According to the Federal Solar Industry Association tax revenue from the photovoltaic industry with € 3 billion in 2008 were higher than the solar - promoting investments ( € 2 billion).

Avoided fuel imports add up to the year 2030 to € 100 billion, avoided environmental costs to € 35 billion.

Despite new competition from Chinese solar module manufacturer, the German economy continues to benefit from the promotion of photovoltaics. A value study of the Renewable Energy Agency determined that the regional value-added benefits not only by the module production, but above all through planning, installation, operation and maintenance.

Further development

Overall, the PV market is still growing strongly ( by about 40% annually ); but other renewable energies, in particular wind power on land, much cheaper per kWh of energy produced. Since the additional costs for renewable energy in accordance with the Renewable Energy Sources Act ( EEG) will be allocated to all consumers, and this leads to considerable extra burden and competitive disadvantage, the remuneration shall be reduced in accordance with the annex. As a result more favorable energy generators are preferred.

Economy

Cost and payback period

A roof-mounted photovoltaic system requires in Germany about 8-9 m2 area per kWp. The costs are, inter alia, depending on the type and quality of the components. The average price for systems up to 100 kWp was in March 2014 at 1450 € net per kWp. This price includes in addition to the modules, inverters, mounting and power supply. An installed in Germany plant supplies depending on the location and orientation of an annual yield of about 700 to 1100 kWh per kWp.

The Renewable Energy Sources Act ( EEG) in Germany guarantees the operators of photovoltaic systems statutory minimum remuneration for the electricity fed into the grid (as of April 2014: 9.19 to 13.28 ct / kWh over 20 years). The operation of photovoltaic systems can thus be economically rewarding. The payback depends on the time of start-up ( due to lower legal fees ), the sunlight, the orientation and tilt of the system, as well as the proportion of debt financing.

Electricity generation costs

The electricity production costs of photovoltaic systems in Germany were in the third quarter of 2013 from 7.8 to 14.2 ct / kWh .. Since 2011 they are in Germany below the domestic electricity price. In other countries, such as Spain, Italy, parts of the USA and Australia, grid parity has already been achieved in previous years. In southern Spain can produce in 2012, according to VDI news photovoltaic systems for 7-9 ct / kWh. The German Institute for Economic Research (DIW ) finds that the cost of photovoltaics have so far fallen far faster than expected recently. Thus, in a recent report of the European Commission was still anticipated capital costs, which " already partly below the values ​​expected by the Commission for the year 2050".

The accompanying table provides the electricity generation costs in cents / kWh, according to a study by the Fraunhofer Institute for Solar Energy Systems. The assumptions follow apart from investment costs and earnings of the study: The underlying real weighted average cost of capital is 2.8 %, the annual operating cost € 35 and the annual yield losses of 0.2%. Other operating expenses or income losses can change the values ​​in the table. Furthermore, it is assumed that a useful life of 25 years. Since PV systems have no moving parts, they are very durable; it is quite conceivable that they remain usable even beyond this period. It is assumed that dismantling and disposal costs are equal to the residual value of the plant. For the calculation of the average cost per kilowatt-hour prices in the year of installation costs as well as income with the real cost of capital previously used are discounted. Furthermore, the electricity generation costs apply only to the case where the power generated is also completely consumed.

For illustration, the table is graded in colors: White boxes are here for costs that are below the current price of 9.71 cents / kWh for large industrial consumers in Germany greyed higher. All values ​​were below the average price for private customers in 2013 of 28.7 cents / kWh. In Germany, the income will be non-tracking systems 700-1200 kWh yield per year and kWp. The values ​​for the average income for new plants are shown in italics in the table.

Module prices

Module prices have fallen sharply in recent years, driven by economies of scale, technological developments, normalization of solar silicon price and by building excess capacity and competition among manufacturers. The average price development since January 2009, according to the nature and origin is shown in the adjacent table. The future price development depends on the development of demand and of technical developments. The low prices of thin-film systems perspective partly for the finished plant by the higher efficiency due to the lower installation costs for plants of the same capacity. It is at the stated prices not retail prices; the cost of the modules have a share of only 40-50 % of the total costs (as of 2012).

Crisis in the European solar industry

Due to sharp decline in module prices in the wake of cheap imports from China has entered a crisis, the European and German solar industry. Many manufacturers went bankrupt. In May 2013, the EU Commission imposed punitive tariffs against China, as that country by enormous government subsidies under the cost of selling ( dumping ). The punitive tariffs are controversial in the industry and environmental organizations. End of July, China and the EU agreed on a minimum price of 56 cents / Wp and a maximum annual delivery amount of 7 GW.

→ more: see Article solar industry

Environmental impact

Production

The environmental impact of silicon technology and thin-film technology are the typical semiconductor manufacturing, with the appropriate chemical and energy-intensive steps. The Reinstsiliziumproduktion in silicon technology is relevant due to the high energy demand and the advent of by- products. 1 kg of high-purity silicon occur up to 19 kg In addition material. Since pure silicon is usually produced by suppliers, the selection of suppliers in environmental terms is crucial for the environmental performance of a module. In the thin-film technology, the cleaning of the process chambers is a sensitive point. Here the climate-damaging substances nitrogen trifluoride and sulfur hexafluoride are used often. The CdTe technology is attributed due to their short energy payback time, the best environmental performance on a life cycle basis.

Operation

2011 confirmed the Bavarian State Office for the Environment, that CdTe solar panels pose no threat to humans and the environment in the event of fire.

With absolute zero emissions during operation, the PV to very low external costs. If these are in power generation from hard coal and brown coal at about 6 to 8 cents / kWh, they amount to only about 1 in photovoltaic ct / kWh ( 2000). This is the result an opinion of the German Center for Aerospace and the Fraunhofer Institute for Systems and Innovation Research. For comparison, the value of 0.18 there also called ct / kWh of external costs is called solar thermal power plants.

Greenhouse gas balance

Even if there is no CO2e emissions in the farm, then PV arrays may not produce CO2e - free transport and assemble. The computational CO2e emissions of PV systems be state of 2013, depending on the technique and location from 10.5 to 50 g CO2e/kWh, with averages in the range 35 to 45 g CO2e/kWh.

After a comprehensive comparison of the Ruhr- University Bochum from 2007 CO2e emissions was still in photovoltaics at 50-100 g / kWh, most notably the modules used and the location were decisive. In comparison, it stood at coal-fired power plants at 750-1200 g / kWh in combined-cycle gas power plants with 400-550 g / kWh, for wind energy and hydropower at 10-40 g / kWh for nuclear energy at 10-30 g / kWh ( without disposal ), and solar thermal energy in Africa at 10-14 g / kWh.

Land Use

PV systems are mainly built on existing roof and road surfaces, resulting in no additional space required. Outdoor systems are only EEG considered eligible if already contaminated surfaces such as conversion areas ( from military, economic, verkehrlicher or habitable use), areas along highways and rail lines ( in the 110 m strip ), areas that are designated as commercial or industrial area or sealed surfaces (former landfills, parking lots, etc. ) are used. These areas do not face seal represents a new approach to design track scientists at the Massachusetts Institute of Technology, directing their solar modules in 3-dimensional space, resulting in a significantly reduced space requirements and increased efficiency of the system resulting.

Recycling of PV modules

So far the only recycling plant runs ( specialized pilot plant ) for crystalline photovoltaic modules in Europe in Freiberg, Saxony. The company Sunicon GmbH (formerly Solar Material ), a subsidiary of SolarWorld, a mass-based recycling rates for modules from an average of 75 % recorded there in 2008 with a capacity of approximately 1,200 tons per year. The amount of waste PV modules in the EU in 2008 was 3,500 tons / year. It is planned by automating a capacity of about 20,000 tons per year.

To set up a voluntary EU-wide, area-wide recycling system founded the solar industry as a joint initiative in 2007, the PV CYCLE association. There are in the EU by 2030 rising 130,000 t disused modules per year expected. In response to the overall unsatisfactory performance drop since January 24, 2012 solar modules under an amendment to the e-waste policy. For the PV industry, the amendment provides that 85 percent of the solar modules sold must be collected and recycled to 80 percent. By 2014, all EU -27 member states have to implement the regulation into national law. They want to take by the manufacturers of their duty to provide structures for recycling. The separation of the modules from other electrical equipment is preferred in this context and existing collection and recycling structures are to be expanded.