Solar cells - perspective source of energy

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Solar cells - perspective energy source for the new millenium

"Most of the trouble in the world is caused by people wanting to be important."
(T.S. Elliot)

Solar-fabrik - Freiburg, Germany

Zero energy building, Solar-fabrik, Freiburg, Germany
(source/copyright: Solar-fabrik AG, pictures 1-3, Denis Lenardic, picture 4).

Welcome to the web site devoted to perspective possibilities of solar energy use. History, technologies and applications of photovoltaic systems are presented here. If there weren't the solar cells, you probably wouldn't be browsing through this web site. Though it sounds unusual at first, it is a fact that solar cells represent a very important part of information technology revolution in the last few decades. Without solar cells there wouldn't be so many communication satellites, which found the information technology revolution. The consequences are fast development in the field of information technologies and computer sciences, Internet etc. Data and voice transfer possibilities, which are offered to you by modern communications techniques, were made possible by a small piece of silicon in the form of a solar cell. Do you think that there are not enough solar energy resources or that solar energy use is not economical? Take a look at the web site and you will find some amazing new information. Further detailed information and answers on the most complex questions on solar energy use are accessible through links leading to web sites of many different organisations and institutions. For a start let me say only that photovoltaic industry, following telecommunication and computer industry, is the third most prospective industry branch in the next decades. Intensive research in the field of solar energy has taken place more than a century ago. The solar energy use does not require fossil or other-more or less poisonous-fuels and it doesn't require much maintenance. No toxic emissions are produced. Supported by suitable financial aid solar energy is fully compatible with other energy sources. Therefore, solar energy is - along with other renewable energy sources (wind, hydrogen, biomass etc.) the most promising energy source for the next decades. I can but agree with the solar pioneer Frank Shuman who, at the beginning of the 20^th century, said: "... it is the most rational source of power ..."

What is photovoltaics

The term photovoltaics derives from the Greek word "phos" meaning light and the word "volt" (named by Alessandro Volta). Photovoltaics is a science, which examines light-electricity conversion, respectively, photon energy-electric current conversion. In other words it stands for light-current conversion. Both direct and diffuse solar radiation take part of the process. The light to current conversion takes place within solar cells, which can be amorphous, polycrystalline or monocrystalline, according to their structure. In most cases they are made of silicon. Most common application of solar cells applies to pocket calculators power supply, parking meters power supply and similar appliances. Solar-module consists of many solar cells, which are electrically connected and placed between glass and tedlar plate, and framed by an (usualy) aluminium frame. A number of solar-modules and other components (batteries, charge regulators, inverters...) can form large photovoltaic systems. Further information on units and symbols used in photovoltaics and in solar energy engineering can be found if you follow the link above.

Application examples

Solar energy - the most promising clean energy source for new generations. Sun has been shinning for about 5 billion years (without malfunctions) and it will continue shinning for another 4 to 5 billion years.

The first PV system applications developed were applied as an energy source for satellites and later for orbital stations in space. Nowadays, photovoltaic systems are applied as an energy source in many cases. Most commonly applied photovoltaic systems can be found in remote and rural areas where no public grid is available. However, quite often grid-connected systems are constructed in urban areas. Photovoltaic systems are an excellent solution to electricity production regardless of your whereabouts - even at high latitudes of Himalayas or in Antarctica photovoltaic systems have been build. According to loads connected to the system and to the basic design principles, the following photovoltaic systems are used - direct coupled photovoltaic systems (systems without batteries - water pumping systems for example), standalone photovoltaic systems, grid-connected photovoltaic systems, hybrid systems (e.g. PV - wind or PV - diesel systems), concentrator photovoltaic systems. The applications below depict use of photovoltaic systems as an energy source in many interesting ways.


Photovoltaic power plants - Solar modules are nowadays parts of large standalone or grid-connected systems. Large photovoltaic power plants (MW range) have beeing constructed in Germany, Spain, USA, Italy, Netherlands etc. Worldwide more than 250 large PV power plants with peak power 1 MWp or more (each plant) are connected to the public grid(s).	Huerta Solar Citruenigo, Spain (Copyright: ACCIONA Energía)
Akademie du Mont-Cenis, Herne, Germany (Photo: Denis Lenardic)	Building integrated photovoltaics - Acronym of BIPV (Building Integrated Photovoltaics) refers to photovoltaic systems integrated with an object's building phase. It means that they are built/constructed along with an object. They are also planned together with the object. Yet, they could be built later on. Due to specific task cooperation of many different experts, such as architects, civil engineers and PV system designers, is necessary. More...
Photovoltaic noise barrier along A9 in Amsterdam (photo: Denis Lenardic)	Noise barriers - An efficient way of noise prevention by application of photovoltaic modules was first demonstrated in Switzerland in 1989. Later, the solution was applied also in some other European countries. Noise prevention is also a research subject of several projects conducted in European Union. Different photovoltaic noise barriers can be built considering motorway features, barrier construction, the height of the barrier, and other factor influence (environment etc.). More...
Disaster relief - Small photovoltaic systems are very good power supply sources in cases of natural disasters (renewing infrastructure and normal life conditions after earth quakes, hurricanes, floods and so on). In such cases photovoltaic systems can be used as power supply sources for medical institutions, schools, street lighting, traffic signalisation etc. More...	Two Japanese filling stations capable of refueling emergency vehicles in disaster situations (courtesy: CADDET)
Electricity source for protected areas - an example of application would be a natural park or other environmentally protected area. Negative influence on the environment is avoided by application of photovoltaic systems in such areas, which cannot be achieved by use of public grid.	Solar power systems around the funicular of Corviglia at Piz Nair, St. Moritz, Switzerland (source/copyright: SunTechnics)
Telecommunication devices supplied by PV systems - Many telecommunications systems can be found in impassable areas making them difficult to reach by ground. The locations can be most difficult to reach during winter with snowfalls increasing the possibilities of systems malfunctions. Many of the systems are used in critical applications, such as railway signalling, telecom facilities for rural areas, marine lights, TV transmitters to name but a few.	Photovoltaic powered radio link and avalanche monitoring system in french Alps (photo: Denis Lenardic)
Alarm and control systems power supply - Numerous fire alarms, burglar alarms and other alarm systems could be powered by photovoltaic systems. Usually an alarm system is connected with a remote monitoring communication system and it is powered by solar cells. Such systems operate independently of a grid power supply, therefore, they can be used in remote areas or in situations, where high reliability is required. The other important group of systems, that could gain a lot from photovoltaic systems, are light signs, marine lights, airport landing lights, heliport lights etc.	Automation and DAQ - many different automated measurement systems can be supplied by photovoltaic systems such as water level sensors, meteorological stations, seismical measurement equipment and other simmilar devices. Remote monitoring is conducted via modem, GSM or ISDN communication. More about monitoring systems for grid-connected photovoltaic inverters you may read here...
Use of PV systems in medical applications - Application of photovoltaic systems has proved very suitable for power supplying medical clinics in rural areas. Photovoltaic systems power lighting, sterilisation equipment, vaccine refrigerators, air conditioning etc. Installation of such systems is most widespread in different African countries. The systems are usually designed as complements to small wind systems or diesel generators, which are used for backup power supply at night or in emergency, such as emergency surgeries, and for x-ray power supply. More...	Photovoltaic artistic projects - Photovoltaic modules can be a powerfull tool for the artistic sculptures and other creations. A very interesting photovoltaic systems demonstration example is the "Solarstraße", a 3.5 km long road section in Gleisdorf, Austria. Along the 3.5 km long stroll about 80 different objects supplied by solar cells can be found. Further information on this interesting stroll is available following the above the link. More...
PV street light, Crete, Greece (source: ISES WIRE Image Library ) PV street lights in Africa (source/copyright: Solar-Fabrik AG)	Street lighting - PV street-lighting is the most applicable in rural areas, where no public grid is available.
Solar powered aircrafts - HELIOS project was a part of NASA's ERAST programme (Environmental Research Aircraft and Sensor Technology). It was developed by NASA and Californian company AeroVironment Inc. ERAST programme develops pilotless solar powered airplane technology. The HELIOS construction is based upon its predecessors like NASA's solar plane Pathfinder, which was successfully tested a few years prior to HELIOS. In the test flight on 13th August 2001, HELIOS reached the height of almost 30,000 meters. More...	Helios - solar powered aircraft (source/copyright: NASA DFRC)
Cathodic protection - cathodic protection of pipelines (gas, oil or water pipelines) can be obtained independently of a public grid by a PV system. More about cathodic protection...	Other interesting application examples - photovoltaic systems can also be used as an energy source in oil drilling platforms or for parking meters to name but a few. Often photovoltaic systems are realised in combination with wind or diesel generators wherever a 24 hours functioning of power supply system is necessary. Some other very important application examples are: PV systems for caravans and boats, rural electrification, solar powered vehicles (cars, boats) etc.

Some photovoltaic related web sites - basic information

Solar Generation IV - Greenpeace and EPIA are joining forces for the fourth time to publish a report on PV solar electricity: Solar Generation IV. Apart from providing an overview of the current worldwide status of PV in terms of policy, technology and economics, Solar Generation contains credible scenarios which prove once again that PV is clearly on the way to becoming a well-established energy source in the coming decades; EPIA, Greenpeace, September 2007 (5663 kB).

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Webmaster's choice - comprehensive report about possible photovoltaic development in next decades.

Literature and more information

European Commission: European Photovoltaic Projects 1999-2002; EU Directorate-General for Research, 2003 (4518 kB).
California Energy Commission: A guide to photovoltaic (PV) system design and installation; California Energy Commission, June 2001 (2,36 MB).