The sun photovoltaic technologies and systems are today one of the most attractive markets of renewable energy. It is explained by the unlimited stream of sun radiation that achieves a terrene and can be caught and regenerate into electric energy by means photosensitive elements.

As the point of departure of the sun photovoltaic elements a 1905 is accepted, when Albert Einstein has given explanation of the phenomenon of photovoltaic effect, or 1941…1946, when american scientist Russell Ohl - the employee of Bell Labs - has open and has patented the first silicon sun element.

To define the perspective directions of the development of sun photoelectricity, the analysis of developments of sun elements in the last few years was conducted, and the parameters and the circle of technical and methodological problems were defined, which in an aggregate stipulated today's development status of sun technologies and set the point of departure in development of technologies in the future.

During many years the photovoltaic solar cells behave to the group of exotic devices and even, economically justified using of sun batteries to power of the space vehicles in the last decades was not able to change the thought about them.

Only in the last decade in connection with the periodic threats of power crisis the substantial query of world society to the photovoltaic solar cells was appeared again. The considerable part of optimism in relation to the solar cells was warmed up by revolutionary successes of electronics, communication means and computer technique. Large power corporations and especially, the accrued enterprises dashed actively, though elementally, to conquer a new unexplored market. But already the first meeting of researchers with the «solar fuel» showed the large complicacy of the unformed market. Every insignificant improvement in energy effectiveness was canceled by disproportionate high financial and material charges. The Moore’s law (the number of transistors on a chip doubling every two years) also malfunctioned at developments of sun elements. In future the optimism of pioneers of photoelectricity outgrew into an alarm, and later into despair. The photoeffect remained to be a complicated physical phenomenon and needed of the subsequent study.

The small possibility to predict the results of scientific researches and the absence of the rapid income in sum brought to cooling of risky sector of market. Large business concerns did not go away from a market fully, but the activity was limited to only the insignificant investments. The small accrued companies with the enough modest financing were not able to compensate reduction of investments in full measure. Therefore, without regard to large expectations, young sun technologies to this time occupy only a small niche (near 1%) of all world market of electric energy and on bird rights in the eyes of officials, industry and users.

If the quality of sun elements requires the considerable improvement, the wide assortment of technologies strikes.

The existent photovoltaic solar cells can be classified in accordance with the linear sizes (with the thickness) of semiconductor structures, according to the type of chemical elements and compounds accountable for a photovoltaic effect; in compliance with a spectral sensitiveness,  according to the principle of division of pathways of charge carriers and photons, according to the phase-morphological composition of semiconductor structure, in conformity with the method of formation of semiconductor structures, in accordance with the chemical composition of matrix, in accordance with the features of creation and principle of origin of charge carriers, in compliance with the method of the use.

In accordance with the linear sizes (thickness) of semiconductor structures the solar cells can be divided into volume (more frequently from silicon) and thin films structures.

According to the type of chemical elements and compounds, accountable for a photo-electric effect, the solar elements are distinguished on the monocomponent elements (silicon Si, germanium Ge) and multicomponent sun elements on the basis of compounds: cadmium telluride CdTe, lead telluride PbTe, lead selenide PbSe, lead sulfide PbS, gallium arsenide GaAs,  copper-indium selenide CuInSe₂ (CIS), copper-indium-germanium di-selenide CuInxGaSe₂ (mixture of semiconductors CuInSe₂ and CuGaSe₂), which is briefly named CIGS, gallium-indium phosphate GaInP₂, indium phosphide/gallium arsenide/germanium (GaInP/GaAs/Ge), zinc-selenium phosphate ZnSnP₂, zinc-germanium arsenide ZnGeAs₂.

In conformity with a spectral sensitiveness the sun elements can be classified on infra-red, ultraviolet and multispectral.

In accordance with the principle of division of pathways of charge carriers and photons the photovoltaic elements are divided into the semiconductor structures, based on the drift of charge carriers in the electrostatic field (p-n- transition structures) and semiconductor structures based on diffusion of charge carriers from an area with low concentration of charge carriers into an area with low concentration of charge carriers. Elements, in which p-n- transition is absent expressly, belong to the second group (sun elements on dyes and sun elements on polymers).

According to the phase-morphological composition the sun semiconductor structure can be divided into single-crystal, polycrystalline, amorphous.

In the compliance with the basis of chemical composition of the matrices materials the solar cells are distinguished as inorganic and organic (polymeric) materials.

In conformity with the method of formation of photosensitive structures and principle of origin of charge carriers the sun elements can be divided into macrostructured and nanostructured.

The major part of solar electricity researches is aimed to develop the next generation of photovoltaic solar cells in both materials and device topologies: single-crystal, polycrystalline, amorphous, and nanostructured inorganic and organic materials; studying of the electronic structure of these materials; implementation in single and multiple junction solar cells to take advantage of optical shifting, multiple exciton generation and hot carrier generation.

The goals of the researches and developments that are executing by industry, laboratories, universities, and other members of the solar energy community are market-oriented and focused on cost reduction, development of manufacturing processes and preparing markets for advanced PV products.

The two main strategies to bring down the cost of photovoltaic electricity are increasing the efficiency of the cells and decreasing their cost per unit area.

Analysis of achievements conducted in photovoltaics, showed that technologies of sun elements are found in the embryonic state. The unique developments, on which the pioneers of a new wave of sun elements leaned, were the results of researches of technologies of photosensitive semiconductor structures, executed in days gone during creation of fiber-optic communication lines, of systems of images peak up and display, of systems of distant sounding of Earth and of some other directions, that needed using small optic-electronic sensors. These special photo-electric elements can not be applied without substantial additional researches.

The hopes on reduction of prices of the sun elements and improvement of parameters of energy effectiveness at the mass production of elements default also. Government programs directed on wide introduction of photo-electric sun elements, inculcated in some countries, did not give the expected results and turn out in most cases unprofitable and a realization of concrete projects of solar power plants for production of clean sun energy in industrial scales brought considerable disappointments and mistrust to young industry.

The large expectations of receiving of rapid results from the use of sun elements did not justify oneself on the reason of high cost and low energy effectiveness of solar cells in comparison with other technologies based on incineration of fossil types of fuel. The other reason was an adherence of big energy companies to the method of tests and errors, which worked in well known branches of power engineering earlier, but malfunctions today in case with young quantum-electronic technologies and, opposite, breaks their development. Objectively, the «skidding» or «slipping» of sun photoelectricity was determined by complication of deep processes which define the work of photovoltaic solar cells and by complication of technologies of production and introduction of sun elements.

During action of these limiting factors the sun elements continue to develop as a part of integral electronics, in shade of traditional power technologies, on enthusiasm of separate scientists. Therefore the sun elements are perceived in some uninformed circles as exotic things - whim of physicists or ghostly creation of engineering mind.

The experience got in the last decade, except for disappointments, had the positive consequences, and, he allowed to do two main conclusions which give hope: a) a sun «fuel» can and is to be one of the main sources of ecologically clean energy for steady development of society; b) technologies of making of photovoltaic semiconductor structures are family with the well worked electronic technologies, and these electronic technologies can be used to improve sun elements.

A substantial breakthrough in introduction of sun technologies is possible only subject to the condition of development of a principally new architecture of the sun elements of future generation, based on the revolutionary quantum-electronic phenomena and made with the use of photo-electric nanostructured materials, which provide high energy effectiveness and reduction of prices of the sun modules. To the new sun elements the requirements of stability of parameters in the wide range of light-spectrum of sun radiation are made: ultraviolet (UV), visible and infra-red (IR). The nature of origin of the electromagnetic radiation requires of subsequent research. It is necessary to study more deeply the quantum-electronic mechanisms of interaction of sun radiation of a different range of spectrum and power with the matter that are in different morphological states; solid, liquid and gaseous. In particular, the mechanisms of interaction of sun radiation with the matter on a nanolevel (with molecules, atoms and ions) and macrolevel (with crystalline grates, domains and all that) need also of the attentive study. In the future it is necessary to study the physical nature of mechanisms of reflection and absorption of photons by the matter and to research a propagation of optical radiation in different physical environments.

These researches in an aggregate are to pawn a scientific and technological base for creation of breakthrough in photovoltaic solar cells by the use of the lasing structure for a quantum strengthening of electric current. The work of these solar cells is based on the phenomenon of channelling of the induced optical radiation of certain wave-length in an electromagnetic resonator with a next resonance strengthening of radiation. The same effect arises up in the scheme of semiconductor laser. In same queue, the increased radiation of certain wave-length initiates an appearance of an avalanche in semiconductor photo-electric structure and an increasing of charge carriers. Such combination of technologies of absorptive elements and irradiative semiconductor lasers allows to create the high effective photosensitive structures of the sun modules with quantum efficiency 50…70 % and higher, depending on the type of semiconductor.

The decision of this circle of scientific-methodological problems will serve as a substantial impulse for development of new photovoltaic technologies and equipment. Successful transition of society to the wide use of the photovoltaic systems is impossible also without creation of a new infrastructure and infrastructural systems of renewable power engineering for transformation, accumulation, transportation and distribution of electric energy. The united efforts of governmental structures, industry and universities are to be directed on the realization of this purpose.

Vasil Sidorov on April 23, 2010 from Technopark QUELTA

E-mail: sidorovvasil@gmail.com