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