Photovoltaic’s (PV) is the direct conversion of light into electricity at the atomic level. The word refers both to the science and the technology, which are based on the photovoltaic effect:
'the generation of a voltage and/or a current, by absorption of light in some material or a combination of materials.'
Electricity that can be used for immediate power - Direct PV Systems - or delayed, with the help of storage technologies. In PV these elements are interconnected by various sciences:
• (Quantum) physics, optics,
• (Bio-) chemistry,
• Engineering,
• Materials science and
• Micro-electronics.
The photovoltaic effect is first observed in 1839 by A.E. Becquerel, a French physicist. The first functional, intentionally made PV device is from American inventor Charles Fritts in 1883 with an efficiency of 0,1 percent. The modern era of PV starts in 1954 when Bell Labs in the USA produces a 6 percent efficient solar cell using silicon as a semiconductor. Five years later the Sputnik 3 is the first satellite using solar arrays, followed by Vanguard I for powering a small radio transistor. A major visual proof for the world that the Sun's energy can be harvested to generate electrical energy.
“Light - a mysterious element that enables people to command nature.”
Sir Francis Bacon, New Atlantis (1627) Radiant energy, in the form of photons.
In the 21st century, supportive government policies in many European countries and Japan,
__partly driven by the Kyoto Protocol.
Climate change and especially the steep rise of oil prices in 2007/08- result in a substantial increase in production. Radiant energy, in the form of photons. In the 21st century, supportive government policies in many European countries and Japan, -partly driven by the Kyoto Protocol, Climate change and especially the steep rise of oil prices in 2007/08- result in a substantial increase in production. Most of the big manufacturers are either divisions or subsidiaries of large companies with diverse manufacturing interests (Sharp/BP/Shell/Kyocera). Most of the research for advanced future technologies takes place in academic and privately owned research centers.
The role of PV-power in the world's overall energy system is still negligible -less than 0.5 percent- with predictions by the industries and environmental organizations that it could raise to 26% by 2040.
"The environmental impact of PV is probably lower than that of any other renewable or non- renewable electricity generating system.” - IEMC Research Center – Leuven [BE]
Is photovoltaic different than other solar energy conversion technologies?
There are a variety of ways to convert sunlight into useful energy. One method used for many centuries is to convert sunlight into heat, which can then be used for building heating or water heating. Two common examples of solar energy into heat are solar pool heating and solar water heaters. There are also two ways to convert sunlight into electricity. One is solar thermal electricity generation, which uses much of the technology from conventional utility electricity generation. In most utility electricity generation, heat is generated by burning a fuel such as coal or by a nuclear reaction, and this heat is turned into electricity. In solar thermal generating systems, the heat is created by focusing sunlight onto a spot rather than burning fuels, but the remainder of the electricity generation process is the same as conventional utility generation.
Photovoltaic’s is another mechanism for converting sunlight into electricity. Photovoltaic"s, (also called solar electricity, solar batteries or solar cells) are fundamentally different in that they convert sunlight directly into electricity without intermediate steps.
Advantages and Disadvantages of Photovoltaic’s:
Photovoltaic systems have many advantages. In many types of applications, PV systems have several important technical advantages that make them the best choice for electricity generation. PV panels are extremely reliable and require low maintenance, they can operate forlong periods unattended, they are suitable for both large and small loads and additional generating capacity can be readily added. These characteristics make photovoltaic"s an ideal technical choice for both remote power and remote residential electricity applications. For such remote applications, a PV-based System is also usually the lowest cost system. There are a number of additional technical advantages, such as the distributed nature of PV power production and the low lead times to installation, which may be beneficial in grid connected installations. In addition to its technical advantages, photovoltaic"s electricity generation is also environmentally benign, with arguably the lowest environmental impact of any of the electricity generating technologies.
The key disadvantage of photovoltaic"s is its relatively high cost compared to many other large-scale electricity generating sources. This disadvantage applies mainly to the use of PV for applications that are already tied to the electricity grid. Another disadvantage is that the power density of sunlight is relatively low. This means PV tends to be less suited to applications that are physically small compared to the amount of power they require. This affects primarily transport applications. Although solar cars, solar trains, solar planes and solar boats have all been made and used, in general these applications are difficult for PV or other solar - based systems.
Photovoltaics:
1. Working of Solar cells
2. Different Solar Technologies
3. Contribution of Art and Design using Photovoltaic’s
1. Working of Solar cells:
Solar cells (or photovoltaic devices) directly convert light into electricity, and usually use similar physics and technology as that used by the microelectronics industry to make computer chips. The first step in the conversion of sunlight into electricity is that light must be absorbed in the solar cell. The absorbed light causes electrons in the material to increase in energy, at the same time making them free to move around in the material. However, the electrons remain at this higher energy for only a short time before returning to their original lower energy position. To collect the carriers before they lose the energy gained from the light, a pn junction is typically used.
A pn junction consists of two different regions of a semiconductor material (usually silicon), with one side called the p type region and the other the n- type region. In p-type material, electrons can grain energy when exposed to light but also readily return to their original low energy position. However, if they move into the n-type region, then they can no longer go back to their original low energy position and remain at a higher energy.
The process of moving a light generated carrier from where it was originally generated to the other side of the pn junction where it retains its higher energy is called collection. Once a light generated carrier is collected, it can be either extracted from the device to give a current, or it can remain in the device and gives rise to a voltage. The generation of a voltage due to the light generated carriers is called the Photovoltaic effect. Typically, some of the light generated carries are used to give a current, while others are used to create a voltage. Electron absorbs light and gains energy, the electron is collected by the pn junction, it leaves the device to dissipate its energy in a load, and then re-enters the solar cell.
The combination of a current and voltage give rise to a power output from the solar cell. The electrons that leave the solar cell as current give up their energy to whatever is connected to the solar cell and then re-enter the solar (in the n-type region) at their original low energy level. Once back in the solar cell, the process begins again: an electron absorbs light and gains energy, the electron is collected by the pn junction, it leaves the device to dissipate its energy in a load, and then re-enters the solar cell.
Working of solar cells.
2. Dfferent Solar Technologies:
Solar cell technologies differ from one another based firstly on the material used to make the solar cell and secondly based on the processing technology used to fabricate the solar cells. The material used to make the solar cell determines the basic properties of the solar cell, including the typical range of efficiencies.
Most commercial solar cells for use in terrestrial applications (i.e., for use on earth) are made from wafers of silicon. Silicon wafer solar cells account for about 85% of the photovoltaic market. Silicon is a semiconductor used extensively to make computer chips. The silicon wafers can either consist of one large singe crystal, in which case they called single crystalline wafers, or can consist of multiple crystals in a singe wafer, in which case they are called multicrystalline silicon wafers. Single crystalline wafers will in general have a higher efficiency than multicrystalline wafers.
Silicon wafers used in commercial production allow power conversion efficiencies of close to 20%, although the fabrication technologies at present limit them to about 17 to 18%. Multicrystalline silicon wafers allow power conversion efficiencies of up to 17%, with present fabrication achieving between 13 to 15%.The efficiency achieved by a solar cell depends on the processing technology used to make the solar cell. The most commonly used technology to make wafer-based silicon solar cells is screen- printed technology, which achieves efficiencies of 11-15%. Higher efficiency technologies are the buried contact or buried grid technology, which achieves efficiencies op up to 18% and has been in production for about a decade.
Although silicon solar cells are the dominant material, some applications – particularly space applications – require higher efficiency than is possible from silicon or other solar cell technologies. Solar cells made from GaAs or related materials (called III-V materials since they are in general made from groups III and V of the periodic table) have a higher efficiency than silicon solar cells, particularly for the spectrum of light that exists in space. GaAs solar cells have efficiencies of up to 25% measured under terrestrial conditions. To further increase these efficiencies, solar cells made from different kinds of materials are stacked on top of one another. Such devices are called tandem or multijunction solar cells (the term multijunction applies to other types of structures as well). Such solar cells have efficiencies of up to 33%.
A final class of solar cell materials is called thin film solar cells. These solar cells can be made from a variety of materials, with the key characteristic being that the thickness of the devices is a fraction of other types of solar cells. Thin film solar cells may be made either from amorphous silicon, cadmium telluride, copper indium diselenide or thin layers of silicon. The efficiencies of thin film solar cells tend to be lower than those of other devices, but to compensate for this the production cost can also be significantly lower of these technologies, amorphous silicon is the best developed, and laboratory efficiencies are between 10 to 12%, with commercial efficiencies just over half these efficiencies. The other thin film technologies are still the subject of development, although commercial products exist. The efficiency of these devices is about 6% to 10% efficient.
Most solar cells will theoretically operate with a higher efficiency under intense sunlight than under the conditions encountered on earth. Concentrator solar systems exploit this effect, by focusing sunlight into a concentrated spot or line. Concentrator systems exist for both silicon and III-V solar cells. Silicon concentrator systems have reached efficiencies of 28% while III-V based systems have reached about 33%.
3. Contribution of Art and Design using Photovoltaic’s:
The cases that are shown in this section provide an overview of art works that have used photovoltaic systems in a functional and/or aesthetic way. All the works presented here have been made after 2000 and -although the aim was to illustrate the use of various technologies- most of them use the predominant Si-based technologies. As the focus of the research is on the off-grid use of PV, all the works presented are not connected to the main power supply. Where possible it is indicated if battery storage was foreseen.
Within this context the aim was to provide also a mix in terms of type of (art) work, the ideas behind it and the setting (indoor or outdoor).
Sweet Responsive PV Water Pump:
Liujia Solar:
A Confucian Stand ('Installation')
Intersolar 2006, Freiburg, GE
PV-Set up:
Off-grid; No storage
PV-Tech: m-Si
Liujia Solar:
A Confucian Stand ('Installation')
Intersolar 2006, Freiburg, GE
PV-Set up:
Off-grid; No storage
PV-Tech: m-Si
London Oasis:
Laura Chetwood (Archs.)
Installation: London, UK, June 16-25, 2006
PV-Set up: Off-Grid, Hybrid PV/Wind;
Storage: Hydrogen fuel cell
PV-Tech: not specified
_(Image source)
SOH19 States of Nature:
Alex Vermeulen – Syndicaat
Landscape Sculpture
Campus Technical University
Eindhoven,
Holland – 2006
PV-Set up:
Off-grid; No storage
PV-Tech:
88 Si-panels
Earthspeaker:
Jeff Feddersen
Acoustic Sculpture
Accra (NY), US, 2006-2008
PV-Set up:
Off-Grid;
Storage:
bank of ultra capacitor modules
(Maxwell Technologies; - 5 55F 15V modules
and one 110F module).
_(Image source)
Drone #2
Autonomous observing system:
Köln, Germany, 2002
PV-Set up: Off-Grid; No storage
PV-Tech: Solar panels; type notspecified
_ (Image source)
Walk:
Laurie Anderson
Series of installations: Aichi Expo 2005, Japan
PV-Set up: Off-grid; no storage (Aimulet LA) &
Grid-connected (other system components)
PV-Tech: Spherical Si
_(Image source)
Bamiyan Afghanistan Laser Project:
Hiro Yamagata
Laser Installation:
Bamiyan City, Bamiyan, Afghanistan
Opening: June 2012
PV-Setup: Hybrid wind/PV; Off-grid; Storage
Batteries & PV-Tech: not specified
_(Image source)
I also went through some of the latest design innovations in the field of photovoltaic technologies.
Collage on the application of latest photovoltaic technologies
