What is Solar? The word solar is derived from the Latin word sol (the sun, the Roman sun god) and refers to things and methods that relate to the sun.

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1 What is Solar? The word solar is derived from the Latin word sol (the sun, the Roman sun god) and refers to things and methods that relate to the sun. What is the solar industry? The solar industry is all the companies who supply the products as a subcontractor for the manufacture of solar cells or which are integrated into the manufacturing and distribution process itself. These are companies and manufacturers who have opened up the entire value chain, and others who carry out only part of the process such as panel manufacturing, engineering (photovoltaic systems), power plants (solar thermal), etc. What is solar energy? Solar energy - is the energy of the sun. The sun radiates about as much energy per second on our planet as would be released during combustion of 200,000 billion tonnes of coal. That s more than 10,000 times the present world energy consumption. The sun provides the earth with two main types of radiant energy: heat and light. The solar radiation that reaches us, a large part already been absorbed by the atmosphere or reflected, is composed of visible light and UV rays that cannot be seen but can be felt, due to the heat they generate, for instance the infamous sunburn. Some solar systems make use of heat, others transform the light radiation into electrical energy. Solar energy is also called alternative or renewable energy, this means, it is an alternative to fossil fuels like oil, gas, coal, or nuclear power. When we talk about solar energy it means that the energy generated is produced directly from sunlight. Edmond Becquerel, a French physicist, is the pioneer within this field; he discovered the photoelectric effect in He noted that certain materials can transform small amounts of sunlight into electricity As at the beginning of the 20th Century Albert Einstein discovered the photoelectric effect and developed the quantum theory which is the basis of the development of the photovoltaic solar cells. Einstein observed that electrical current was created when light strikes a metal surface. The world s first solar collector was built by Horace de Saussare, a Swiss scientist, in The first solar cells were built in 1880 (with an efficiency of 1-2%), more

2 advanced solar cells were developed in the 1950s and 1960s for the space program, this served as an ideal energy source, but were not for general use due to the high production costs and low efficiency in comparison to the then more economical conventional forms of electricity production. The first solar cells were produced in the 1970s for general use; they were produced as a reaction to the increased interest in alternative energy sources and increasing demand on energy. Technological developments since then have led to improved efficiency and falling production costs. The solar technology has advanced dramatically, from a single solar cell to solar panels which can supply entire cities with power. How is electricity produced from light? Some solar systems make use of the heat, others transform the light radiation into electrical photovoltaic energy ( PV ). The word Photovoltaic is a combination of the Greek word for light and the name of the physicist Alessandro Volta. PV stands for the direct conversion of sunlight into electrical energy. Photovoltaic systems use the photovoltaic effect to produce one of the most environmentally friendly forms of generating electricity. If sunlight falls on a semiconductor - usually made of silicon - electrons are released. The most commonly known solar cell is configured as a large-area p-n junction made from silicon. As a simplification, one can imagine bringing a layer of n-type silicon into direct contact with a layer of p-type silicon. In practice, p-n junctions of silicon solar cells are not made in this way, but rather by diffusing an n-type dopant into one side of a p-type wafer (or vice versa). If a piece of p-type silicon is placed in intimate contact with a piece of n- type silicon, then a diffusion of electrons occurs from the region of high electron concentration (the n-type side of the junction) into the region of low electron concentration (p-type side of the junction). When the electrons diffuse across the p-n junction, they recombine with holes on the p-type side. The diffusion of carriers does not happen indefinitely, however, because charges build up on either side of the junction and create an electric field. The electric field creates a diode that promotes charge flow, known as drift current that opposes and eventually balances out the diffusion of electrons and holes. This region where electrons and holes have diffused across the junction is called the depletion region because it no longer contains any mobile charge carriers. It is also known as the space

3 charge region. What is a solar cell? Over 95% of all solar cells produced worldwide are made of the semiconductor material silicon (Si). Silicon has the advantage that it is the second most abundant element in the earth s crust and is available in sufficient quantities and the processing of the crystal is relatively environmentally friendly. Depending on the crystal there are three types of cells: monocrystalline, polycrystalline and amorphous. The different cell types differ in their production costs and in turn differ in efficiencies. The efficiency of amorphous cells (so-called thin-film cells ) are lower than the other two cell types, but they are cheaper because of the less complex manufacturing processes. From the solar cell to the module At full sunlight about 1,000 watts per square meter falls on a solar cell the size 10 x 10 cm solar cell, producing an output of about 10 watts. Such a cell can deliver electric power of To increase performance multiple cells can be combined and interconnected to form a solar module. The connection of several modules is known as a solar generator. Which Parts form a photovoltaic system? Photovoltaic systems normally consist of A.) The solar cells, which are combined in solar modules. Solar modules are the most important part of a PV system. A solar system consists of many interconnected solar modules. Due to different geographical irradiation values, the geographical location plays a very important part in the energy production process. The manufacture of solar cells can be divided into following main processes: First, Polycrystalline (Mono and Multi) are solar cells with a market share of about 90% (2007) made from silicon wafers. Furthermore, there are thin-film solar cells, manufactured using vacuum technology, with a market share of 9% (2007). For thin-film solar cells, various metal alloys are used: silicon, in the form of amorphous silicon, cadmium telluride (CdTe) and cadmium-indium-gallium-selenium (CIGS) and finally concentrator solar cells with a market share of 1% (2007). While in the semiconductor industry, 99.99% pure silicon is necessary (known as the 9N), the purity requirements in the solar market are much lower. B.) The inverter. The solar inverters convert the electricity from direct cur-

4 rent (DC) into alternating current (AC). This can then be fed into the grid or to the household to be used for household appliances. C.) The supply meter. This meter counts the quantity of the electricity fed into the relevant grid. D.) The fixing system. In the field solar panels are mounted on an undercarriage. The fixing system can either be mounted rigidly with a fixed inclination or as Tracker system where the solar modules on one or two dimension tracker axis which will track the sun. E.) The Grid Connection As part of the approval process for a solar system, the connection point will be determined where the wiring of a solar plant is connected to the grid. In addition, often a (remote) monitoring and a data visualization system will be installed. What exactly is a kilowatt peak (kwp)? KiloWatt Peak stands for excellence (English Peak = peak). This value indicates the performance that is achieved by a solar panel in full sunlight (under defined standard test conditions). As a standard condition of an optimal set of solar radiation is 1000 watts per square meter, which is achieved in Germany during the noon hours of a beautiful Summer s day. The peak power is referred to by most manufacturers as the nominal power or power. Since it is based on measurements under optimal conditions the peak performance does not reach optimal performance levels under real exposure conditions. This is because of the strong heating of the solar cells, in practice this means about 15-20% reduction in output. Efficiency factors? The efficiency describes the ratio of input energy and usable energy. The higher the efficiency the better the ability to convert incident light into electricity. We distinguish cell, module and system efficiency. In the commercial mass production currently a cell efficiency is achieved, depending on the technology used the cell efficiency is up to 18.3%. The module efficiency refers to the entire module area and is therefore always somewhat smaller than the cell efficiency. This is due to spaces between the rows of solar cells in the module. The system efficiency refers to the complete solar power system. Efficiency of the system with regards to the drop of power is also a factor, for example due to transmission losses caused by cables.

5 Are clouds a factor? PV modules use not only the direct sunlight in a clear sky, but also the socalled diffuse light radiation in cloudy weather. The brighter it is outside, the higher the performance of the modules - it does not matter if the sun is visible directly or indirectly. In Central Europe we see a ratio of 50% diffused light and 50% direct sunlight. Bad weather will reduce energy production of PV systems. For every location the solar experts consider in their studies, the typical average weather conditions. Nevertheless, the annual solar yield differs from the average. Solar systems are designed so that they can withstand almost any weather condition. Lightning storms or winds up to 120 kilometres/ hour and extreme temperatures are factors that solar systems can resist. In addition, solar systems are insurable in such events as damage. Modules - the cooler the better! Often overlooked is that PV systems usually run optimally at 25 C. The proportion of direct solar radiation for example at the equator, although comparatively higher than in European latitudes, however the high temperature reduce the yield of the plant by the heating of the modules significantly. In standard silicon cells the power drop is about 0.4% per C. The cooler temperatures in Germany compensate so the weaker radiation noticeably. What determines the revenues of a PV system? The generated income of a solar system is determined by three main factors: the level of solar radiation, the efficiency of the modules the expected availability of a system (e.g, downtime due to system failure.) The level of the solar yield is determined by solar irradiance opinions, the level of the income of a PV plant can be determined by the level of the solar yield determined by geographic position and weather conditions. The efficiency of the modules is guaranteed normally by the manufacturers. If the level of efficiency falls in a predetermined level within a given period, usually a penalty to the owner of the solar system is paid. The availability of the system is guaranteed as a rule by an operating and maintenance contract set in effectiveness by a specialist company for the duration of the plants lifetime (usually 20 years).

6 The kilowatt-hours multiplied by the legally guaranteed feed-in tariff (in the countries where this is guaranteed by the state e.g, Italy) shows the expected annual revenue of the solar system. Is solar energy much more expensive than conventional energy sources? Grid parity - a point at which photovoltaic electricity is equal to or cheaper than conventional sources - has been achieved already in some places with high solar radiation and where fossil fuels must be imported. (e.g.islands such as Hawaii). It is expected that other regions in the near future also can reach grid parity. In many parts of the world, however, the production of energy from solar power is more expensive than from fossil fuels. As fossil fuels are one of the leading sources of pollution and carbon dioxide emissions and finite such as North Sea gas, governments around the world, have recognized the need to move towards more sustainable energy sources (solar, wind, geothermal, biomass and hydropower). Thus, for example, the European Union will apply the 20% by 2020 target for its energy from renewable sources. State subsidies and feed-in tariffs have been developed to achieve this goal. Investment in these technologies should be stimulated by high profitability. The current government (the German Government) supports other countries in Europe with energy policy towards a higher proportion of renewable energies. Technical progress is enormous, so that the grid parity moves closer. What are Feed-in tariffs? Feed-in tariffs for solar energy are the most important support from European governments. In countries with fixed legislation towards renewable energy investments in solar technologies can be seen. (Germany and Spain). Many other countries have also followed this policy recently. Feed-in tariffs guarantee a fixed price for the produced solar-energy. We have to accept existing variations of inflation and market compensation. For the owner of a solar plant, the investment is very attractive due to the guaranteed feed-in tariffs and relatively low risks, this leads to high and predictable cash flows.

7 Why invest in solar energy? The energy suppliers are the largest investors in renewable energy, due to commitments by energy companies, to invest a minimum proportion of their turnover into renewable energy. These requirements may be realized either by building or by purchasing renewable energy projects or by buying CO2 allowances. Institutional investors such as Pension Funds and Mutual Funds are also major investors in renewable energy due to the fact these assets are longterm with reliable cash flows