ENERGY-EFFICIENT PHOTOVOLTAIC INSTALLATION

In this paper R&D basics for photovoltaic installation development are presented. Efficiency of energy conversion process depending on the azimuth and zenith angles of the installation\u27s rotation is investigated. Recommendations on the installations\u27 class design are given. Technical and economic assessments of the proposed solutions are made

ENERGY-EFFICIENT PHOTOVOLTAIC INSTALLATION

Abstract In this paper R&D basics for photovoltaic installation development are presented. Efficiency of energy conversion process depending on the azimuth and zenith angles of the installation's rotation is investigated. Recommendations on the installations' class design are given. Technical and economic assessments of the proposed solutions are made. Key words: solar tracker, solar cell, acrylic concentrator, efficiency, photovoltaic modules. Currently in Russia there is an acute problem of the lack of cheap electricity in the areas with decentralized electric power supply. Now that area is embracing about 70 % of the country with a population of 20 million people [1]. Currently stand-alone diesel systems use allowы to get only a very expensive electric power, which in some towns costs under 56 rubles per kW·h and above. It is therefore very important in such areas to use autonomous renewable energy sources, which include solar energy. Now solar power engineering development is progressing at a rapid speed -30% per year. In 2013 the solar power plants of total power about 30 GW were put into operation, whereas the total power in 2012 was 102 GW. In addition, taking into account the purity and the prevalence of renewable energy sources, solar energy is one of the most promising. But at the present moment solar power plants have two weighty drawbacks, delaying their mass distribution. The drawbacks are the high price of solar cells and relatively low efficiency of conversion the solar energy into electric energy during the entire day. The aim of this work is to search the appropriate methods of increasing the efficiency of solar energy conversion into electric energy and to develop the experimental sample of the installation. The high price of solar power plants is determined primarily by high cost of photocells per kW of electric power. If the efficiency of photocells is increased using, for example, instead of single-crystal cell (efficiency 15-17%) gallium arsenide cells (efficiency 30-35%), the cost is increased many times (about 40 times) -from about 2,5$to 100$ per kW, respectively. Therefore it is more promising not to increase the efficiency of photovoltaic cells, but to amplify the incident solar energy since the output power of photocell is almost directly proportional to the incident solar energy. There are 2 ways to do this: to orient the solar panel on the sun by using a solar tracker or to concentrate solar energy by using a solar concentrator. Solar concentrator is a device that allows to collect solar energy from a larger area and direct it to a smaller area. Now solar concentrators are mainly represented by parabolic mirrors and Fresnel lenses. There are also other various mirror systems with different degree of concentration, but they are not widely used due to various weighty drawbacks. Parabolic mirrors are very large and heavy because of their design, which does not allow to make them smaller. Hence the system is subjected to an increased risk of breakage. The mirrors also require very precise orientation to the sun and powerful cooling systems, otherwise their efficiency is extremely reduced. Fresnel lenses have a smaller, but still substantial thickness, and also require more precise orientation and more powerful cooling. Moreover they are quite expensive. In the present work a unique acrylic solar concentrator that solves the problems mentioned above is proposed. 39

PGE2 concentration in teeth pulp tissue as a marker for the effectivenes of different types of treatment for periodontopathy

Activation of the immune system, followed by an increase in the concentration of different immune mediators (among which is found PGE2)is observed during different types of infections and diseases. In our experiment, we monitored the concentration of PGE2 in patients with generalized periodontopathy. The disease is characterized by severe inflammation of the gingival tissue