RVS COLLEGE OF ENGINEERING AND TECHNOLOGY
DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING
DUAL EFFICIENT SOLAR PANEL
(A BREAKTHROUGH IN RENEWABLE ENERGY RESOURCES)

AUTHORS:
1)SATHYA N 2)VIJAYALAKSHMI K 3)SUMITHRA S III Yr – EEE III Yr – EEE III Yr – EEE sathya.sathyanatesan@gmail.com v2.28.kavi@gmail.com sumithras60@gmail.com PH : 82209 90854 PH : 97892 21605 PH : 99655 27343

CONTENTS * PROBLEM STATEMENT * ABSTRACT * INTRODUCTION * CONVENTIONAL SOLAR PANEL * WORKING OF SOLAR PANEL * PROPOSING SYSTEM * A THERMIONIC EFFECT * THERMIONIC CONVERTER * PARABOLIC CONCENTRATORS * PROPOSED SET UP * CONCLUSION

PROBLEM STATEMENT:
Generally the solar panels are considered to be inefficient for harnessing electrical energy due to the fact that the efficiency we are obtaining out of solar modules is of the range of 20-30%.
Because the light energy only utilized by the solar panel for the production of electricity in the meantime the heat energy from the sun is left wasted in current situations.
ABSTRACT:
In our paper we are proposing some ideas in which it is possible to harness the light energy as well as heat energy from the same solar panel modules to generate electricity.
Solar panels utilizing light energy. So we don’t have much more problem in it. But to make use of the heat energy Caesium coating is provided. By using the thermionic effect heat energy is turned to electrical energy.
INTRODUCTION:
The population of the world increases tremendously which result in the great demand in every aspect of life. But for the overall development of a nation or the whole world depends on the energy (more specifically electrical energy) in economical manner. The resources which are used in the present situations for generation of electrical energy are estimated to deplete in a countable years. So it is very important to provide alternates for the existing schemes. On such a way only solar energy harnessing methods were come in to real world existence. But it is very undesirable when expected output is not obtained. So in our paper we are suggesting some novel ideas which are helpful in increasing the output in solar modules in the meantime it is reliable, economical.
CONVENTIONAL SOLAR PANEL:

Solar panels which are used and marketed in commercial world use light energy alone from the sun light. But the remaining heat energy is wasted. The conventional solar panel working is explained below. A solar panel is an electronic device which directly converts sunlight into electricity. The working principle of solar panel is photovoltaic effect. Light shining on the solar cell produces both a current and a voltage to generate electric power. This process requires firstly, a material in which the absorption of light raises an electron to a higher energy state, and secondly, the movement of this higher energy electron from the solar cell into an external circuit. The electron then dissipates its energy in the external circuit and returns to the solar cell. A variety of materials and processes can potentially satisfy the requirements for photovoltaic energy conversion, but in practice nearly all photovoltaic energy conversion uses semiconductor materials in the form of a p-n junction.
WORKING OF SOLAR PANEL:
When a photon hits a piece of silicon, one of three things can happen: 1. the photon can pass straight through the silicon — this (generally) happens for lower energy photons, 2. the photon can reflect off the surface, 3. the photon can be absorbed by the silicon, if the photon energy is higher than the silicon band gap value. This generates an electron-hole pair and sometimes heat, depending on the band structure.

Band diagram of a silicon solar cell, under short circuit conditions.
When a photon is absorbed, its energy is given to an electron in the crystal lattice. Usually this electron is in the valence band, and is tightly bound in covalent bonds between neighboring atoms, and hence unable to move far. The energy given to it by the photon "excites" it into the conduction, where it is free to move around within the semiconductor. The covalent bond that the electron was previously a part of now has one fewer electron — this is known as a hole. The presence of a missing covalent bond allows the bonded electrons of neighboring atoms to move into the "hole," leaving another hole behind, and in this way a hole can move through the lattice. Thus, it can be said that photons absorbed in the semiconductor create mobile electron-hole pairs.
A photon need only have greater energy than that of the band gap in order to excite an electron from the valence band into the conduction band.
When a load is connected externally to the above set up will produce electron flow in the connected load.
PROPOSING SYSTEM:
In our proposal we are making a certain alternation in order to harness the wasted solar energy in the form of heat. In our set up we are providing a caesium layer coating in the existing solar panel modules by which the heat in converted into electrical energy by adoption of thermionic emission. To achieve the maximum production of electrical energy it is very important to maintain the temperature above 200°C.To get such a level of temperature we are providing the parabolic concentrators.
WHAT IS A THERMIONIC EFFECT & THERMIONIC CONVERTER..?
THERMIONIC EMISSION:
Thermionic emission is the heat-induced flow of charge carriers from a surface or over a potential-energy barrier. This occurs because the thermal energy given to the carrier overcomes the binding potential, also known as work function of the metal. The charge carriers can be electrons or ions, and in older literature are sometimes referred to as "thermions". After emission, a charge will initially be left behind in the emitting region that is equal in magnitude and opposite in sign to the total charge emitted. But if the emitter is connected to a battery, then this charge left behind will be neutralized by charge supplied by the battery, as the emitted charge carriers move away from the emitter, and finally the emitter will be in the same state as it was before emission. The thermionic emission of electrons is also known as thermal electron emission.
THERMIONIC CONVERTER: A device for the direct conversion of thermal energy into electrical energy on the basis of the phenomenon of thermionic emission.

The simplest type of thermionic converter consists of two electrodes separated by air gap. One electrode is the cathode, or emitter, and the other is the anode, or collector. The electrodes are made of refractory metals. A heat source supplies enough thermal energy for appreciable thermionic emission to occur from the surface of the metal. After passing through the inter electrode gap, which is a few tenths of a millimeter in size, the electrons impinge on the surface of the collector, where they create an excess of negative charge and increase the collector’s negative potential. If heat is continuously supplied to the emitter and if the collector, which takes up heat from the electrons that reach it, is correspondingly cooled, then an electric current will be maintained in the external circuit, and work will thus be done. Since a thermionic converter is essentially a heat engine whose working fluid is an “electron gas” (the electrons “evaporate” from the heated emitter and “condense” on the cooled collector).
PARABOLIC CONCENTRATORS:
As explained earlier it is necessary to maintain the temperature above 200°C. To achieve this we are going for the parabolic concentrators.

Parabolic dish concentrating systems use parabolic dish shaped mirrors to focus the incoming solar radiation onto a receiver that is positioned at the focal point of the dish.
The optical principle of a reflecting parabola is that all rays of light parallel to its axis are reflected to a point. A parabolic trough is simply a linear translation of a two-dimensional parabolic reflector where, as a result of the linear translation, the focal point becomes a line. These are often called line-focus concentrators. A parabolic dish (parabolic), on the other hand, is formed by rotating the parabola about its axis; the focus remains a point and is often called point-focus concentrators. If a receiver is mounted at the focus of a parabolic reflector, the reflected light will be absorbed and converted into heat (or directly into electricity as with a concentrating photovoltaic collector). These two principal functions, reflection to a point or a line, and subsequent absorption by a receiver, constitute the basic functions of a parabolic concentrating collector. The engineering task is to construct hardware that efficiently exploits these characteristics for the useful production of thermal or electrical energy. The resulting hardware is termed the collector subsystem.
PROPOSED SET UP:
In our proposed set up the conventional solar panel connections are taken without any alternation.

Here we are forming an additional cesium coated layer over the solar panel modules. To utilize the heat we are going for the technique called “thermionic emission”. But we are in the need of temperature above 200°C. To get such a high temperature range parabolic concentrated mirrors are provided. So maximum up to 800°C can be obtained with this set up. The above diagram will clearly depict the set up that we are proposing.
Solar panel will act as a hot electrode. By the provision of parabolic concentrators the temperature of the solar panel is increased above 200°C. Due to the thermionic emission electrons are emitted from the surface of the solar panel (silicon or gallium nitride) and they will be trapped by the molybdenum electrode (cooling electrode) which is placed above the solar panel modules. When an external load is connected to the hot and cold electrode it will constitute a current.
CONCLUSION:
Our proposed idea will make a new way in harnessing the heat energy from the solar panel modules since it uses both the light energy as well as the heat energy which increases the efficiency of the system compared to existing one. This will create a breakthrough in the renewable energy sources and it is economical.