Rural and remotely located areas in underdeveloped and developing countries may now utilize solar cells as a source of renewable, pollution free, and everlasting source of electrical energy. Photovoltaic can be used for pumping well water, in public buildings power use, and domestic appliances. With the continuous increase of solar cells efficiency and decrease in cost per peak power by mass production and market competition, the time is appropriate to spread the application of terrestrial solar cells in economically disadvantaged countries that do not have a national electric power grid. The University of New South Wales in Australia has perfected a remote area power system (RAPS) that can be technically transferred world wide for autonomous as well as grid connected photovoltaic and has been successfully applied in the athlete Olympics/2000 village, in Sydney.

Renewable sources of energy from the sun, wind, small hydroelectric, biomass and geothermal energy have been long recognized and developed. During 1973, the oil crisis in the Middle East had encouraged the industrial world to actively support the continuation of the development of renewable energy sources and in particular solar energy. Sun light is abundant, inexhaustible, clean, and everlasting. Solar cells or photovoltaic convert the sun light of various frequencies (or wavelength) into electric current by the generation of electron-hole pairs in a semiconductor or a P-N junction. Electron hole pairs have negative and positive charges respectively. When electrons and holes are subjected to an electric field, they flow in opposite directions. The flow of electrons and holes create the total current or generate electricity from the sun. Semiconductors consist of elements from group IV of the periodic table (Si, Ge) or compound elements from group III_V or group II-VI, for example GaAs or CdS respectively. Depending upon the energy gap of the semiconductor and the corresponding wavelength of the sun spectrum, electric power or energy can be harnessed from the sun.

Solar cells can be connected in series and/or in parallel to form a solar module or an array of solar modules to generate more electric power. Solar cells produce pollution free electric energy, require no or little maintenance, have no moving parts, are reliable, and can last for decades. Solar modules have been used in space application to provide power for satellites and the permanent space station. For terrestrial applications of solar cells the cost of photovoltaic must be competitive compared to traditional source of power generation. Solar cells efficiency must be increased and the cost per unit Watt peak must be decreased.

The recent price increases of crude oil per barrel and the consequent gasoline prices per gallon at the pump prices in the USA from $0.95 December of 1999 to $2:00 this summer of 2000 can only indicate that crude oil prices will continue to increase. In addition, the worldwide crude oil consumption has increased and the worldwide crude oil reserve will continue to decrease. In case of a natural or human made disaster in the crude oil producing countries, the impact will be very expensive to the consumers.

Remarkable progress was achieved with respect to photovoltaic solar cells efficiency and the unit price per watt. In USA at the Renewable Energy Laboratory (NREL) [1] as well as other centers in USA universities [2] have continued research and development and applications of solar energy. Similar efforts were made at the university of New South Wales (UNSW) [3,4,5] in Australia, in Japan, Germany, the Netherlands, and Switzerland [5]

Autonomous hybrid photovoltaic/Diesel system electric generation [3] for remote area power system (RAPS) and grid integrated photovoltaic has been recently successfully accomplished in the Sydney 2000 Olympics [4] as a milestone for the largest village of photovoltaic in the world. The Green Olympics made up of 600 homes to be occupied by 15,000 athletes will use 1 KW rated photovoltaic array that will generate over 1 million KWhs per year of green power that will save up to 6 tons of carbon dioxide per household annually.

Underdeveloped and developing countries, and in particular those that lie within the tropics, experience an enormous amount of sun shining days year around. Some of those countries are economically underdeveloped and crude oil, coal, and natural gas are not among their natural resources or have not yet been fully discovered. The opportunity to harness the sun as a continuous source of electric and thermal energy supply exists but may not be economically feasible as compared to traditional sources of power generation from coal or gas. This paper is written to address the fact that the time may be appropriate to use solar cells to generate electric power for use at home, public building power needs, or the industry in underdeveloped and developing countries with the strong support and encouragement of the respective governments and the United Nations.

The efficiency of solar cells from single crystal silicon have been improved in the late 1970 and the early 1980 with an approximate efficiency of (10%-12%). Ploy-crystalline silicon and amorphous silicon solar cells with much less efficiency (5-7%) were also developed with less cost. Thin film solar cells, that use only a very small layer of single crystal silicon deposited on glass, were fabricated and developed in order to automate and decrease the cost of solar cells for terrestrial applications. Multi-layer or multi-junction solar cells were also developed where multiple p-n junction that were deposited one layer on top of another to form stacked p-n junction layers have been also successful. In multi-layer solar cells, the p-type layers are connected together and all the n-type layers are connected together using the technique of buried contact solar cell (BCSC) [6]. These solar cells were developed for large scale production that can reduce the cost to a target of $2 per peak watt in Australia.In addition, less expensive solar cells with a lower efficiency were made using CdTe or CuInSe.

Tandem (or series connected) solar cells that can utilize the total solar spectrum with different wavelengths were developed. Solar cells are stacked with respect to the energy gap of the semiconductor. Large energy gap solar cells are built close to the surface facing the sun radiation and smaller energy gap solar cells are built towards the bottom. The first layer of solar cells absorbs the high frequency light and allow the lower frequency light to pass through to the bottom solar cells with the smaller energy gap. Solar cells with three different energy gaps have been fabricated with a higher efficiency for use in spacecraft. Solar cells using the passivated emitter and rear locally diffused cells (PERL) were developed by the University of New South Wales, in Australia with an efficiency of 23%. Silicon dioxide is grown on the surface (passivation), reduces the effect of the surface recombination velocity, and therefore improves the efficiency. The emitter junction is heavily doped locally using diffusion. New ideas are still on progress by targeting an efficiency double the present efficiency of 15% to 17% are being developed as the third generation solar cells. This remarkable progress in solar cell efficiency and cost indicates that solar cells and photovoltaic applications are here and are ready for terrestrial use [6].

Renewable and pollution free natural energy resources have been used in projects and programs throughout the developed, developing, and underdeveloped countries to provide clean power to people who have no grid power, whose grid power is unreliable, or who can not afford to purchase electric power. Projects and programs have been implemented as both government sponsored programs and as private programs with varying success and achievements. Photovoltaic applications, in rural and remotely located areas away from the national or urban grid of electric power, has been achieved [7,8,9]. They are used for pumping drinking or irrigation water, for operation of metrology instruments, for telecommunications repeaters, for battery charging, and for stand-alone or hybrid photovoltaic/diesel generator electric power. These photovoltaic are used in public building (schools or hospitals), in the industry, and domestic every day home appliances. Domestic home appliances may include refrigerators, ranges, mixers, dishwashers, toasters, ironing, computers, radios and televisions and all possible electric powered instruments. Solar cells have also been used to power calculators, watches and clocks.

Successful experiments of remote area power system (RAPS) were accomplished in Australia as a stand alone hybrid system in Montague island, in Kalbari western Australia and rural locations. Grid connected photovoltaic were used in Germany rooftops, Japan rooftops, and the USA rooftops with a remarkable success of pay back policy. This policy allows power to be sold to the electric power company during the day and bought back during the night by the consumer. In the Olympic village for the 2000 games, 600 homes will use building integrated photovoltaic to accommodate all the athletes that will participate in the Olympic competition. This is the largest grid connected building integrated photovoltaic applications in the world.

Electric power supply for public buildings like schools and medical care buildings in remotely located areas in underdeveloped and developing countries is necessary. Building integrated photovoltaic (BIPV) must be used on rooftops as a stand-alone hybrid power system with the support of the respective government, the United Nations, and privately funded projects. With the increase of the crude oil prices, the increase of the efficiency of the solar cells, and the decrease of the price of solar cells toward a target $1-2 range will make the application of photovoltaic as competitive as the other traditional sources of power supply.

1. The US Department of Energy's premier laboratory for renewable energy and energy efficiency research, development, and deployment. www.nrel.gov.

2. Florida Solar Energy Center, www.fsec.ucf.edu

3. R. Corkish, R. Lowe, R. Largent, C. B. Honsberg, R. Constable, and P. Dagger, "Montague Island Photovoltaic/Diesel hybrid System", Center for Photovoltaic Engineering, UNSW, http://www.npws.unsw.gov.au

4. M. A. Green, "Photovoltaic in the Sydney 2000 Olympics: The World's Largest Solar Village", http://www.npws.unsw.gov.au

5. Muriel Watt, John Kaye, Dean Travers, Iain MacGill, "Opportunities for the Use of Building Integrated Photovoltaic in NSW", Photovoltaic Specilaist Reserch Center, UNSW. March 1999.

6. M. A. Green, "Silicon Solar Cells: Advanced Principles and Practice", Center for Photovoltaic Devices and system, UNSW, Sydney, 1995.

7. Center f for Photovoltaic Engineering UNSW, "Grid Comnnected Photovoltaic", http://www.pv.unsw.edu.au/info/gidconn.html.

8. Center f for Photovoltaic Engineering UNSW, "Little Bay Energy Research Facility", http://www.pv.unsw.edu.au/info/gidconn.html

9. Center f for Photovoltaic Engineering.UNSW, "Remote area Power Supplies (RAPS) ", http://www.pv.unsw.edu.au/info/gidconn.html