- 5.5.1 Findings of the Project. - Figure 1.7 shows the impact of the environment on health. - An unhealthy workforce is bound to (1) enhance medical expenditure, (2) reduce productivity, and (3) contribute to the lower economic growth of the nation. - 1.7 Impact of the environment on health. - CO 2 mitigation could be one of the options to reduce emission.. - Only around 2% of the world’s primary energy is currently provided by ‘‘new’’. - Among those low power appliances, domestic lighting is certainly one of the most demanded. - The lower the air mass, the less will be the influence of the atmosphere.. - The top of the solar cell (n) is of low potential and the bottom (p) of high potential when the cell is exposed to light. - The intensity of the incident light (number of photons).. - The wavelength of the incident light (energy of individual photons or color of the light) in correspondence with the semiconductor band gap.. - They display sensitivity according to the wavelengths of the absorbed photons. - 2.8 I–V curves of a solar cell under increasing illumination, the square type shape represents the ideal behavior of the solar cell. - of the cell to the top of the cell. - The larger the surface area of the cell, the greater will be the I SC. - The top side of the solar cell is of negative voltage and the bottom is positive. - The Fill Factor (FF) is a measure of the quality of the solar cell. - The graphical evaluation of the FF is given by the ratio of the two rectangles in Fig. - the better the quality of the solar cell.. - 2.12 Measurement of the open circuit voltage of a solar cell. - The efficiency of a photovoltaic solar cell is the ratio of the electrical power output P out , compared to the solar optical power input (irradiance 9 surface area of the cell), P in . - this gives the efficiency of the solar cell as:. - (2.5) of the I–V curves of the solar cell:. - In the regime where R S is important, the combination of the above equations will give:. - When there is a temperature increase, the band gap of the semi- conductor decreases. - Fullerene called C 60 and derivates are of the most used electron acceptors. - The charging current will depend on the power of the solar panel. - inclination angle equal to the latitude of the location (Fig. - In case of a static and permanent installation the solar panel should be installed with an angle equal to the latitude of the location.. - A charge controller monitors the charge level of the battery. - Charge controllers monitor and manage the charge status of the battery. - There are different types of power inverters based on the shape of the converted signal:. - The shape of the square wave is shown in Fig. - Difficult to recycle because of the Cadmium. - So far we did not mention about the technology of the lighting system.. - 2.4.5.1 Comparison of the Three Lighting Systems. - The electric power consumption will depend on the type and efficacy of the chosen light source. - The specifications of individual elements of the lighting photovoltaic kit are presented in Fig. - 2.37 Individual elements of the lighting photovoltaic kit. - Spanggaard H, Krebs FC (2004) A brief history of the development of organic and polymeric. - It depends on the wavelength of the emitted light because of the sensitivity of the human eye. - It is a measure of the perceived power of light. - The definition of the lumen is based on the definition of the candela.. - The light level is a very good indicator of the efficiency of the power source.. - The luminous efficacy is wavelength dependent as the luminous intensity (in lumens), which is based on the sensitivity of the human eye. - A p-n junction has specific properties different from that of the single p- or n-type semiconductors. - A homojunction is a p-n junction made of the same material. - Electrons belonging to the valence band cannot par- ticipate in the conduction of the electric current as they are attached to atoms. - The band gap of semiconductors will determine the color of the LED (Fig. - The light emitted in the direction of the substrate is either reflected or absorbed depending on the nature of the substrate.. - The color of the light depends on the band gap of the semiconductors.. - and depends on the epitaxial structure of the material.. - It does not necessary determine the color of the LED. - this is because of the band gap decrease in semiconductor with increasing temperature. - The power-supply reference voltage and the value of the current-sense resistor determine the LED current. - The period of light emission will consequently last less than half of the cycle. - It informs about the fidelity in the appearance of the colors as the light source may allow the human eyes to perceive them. - CIE Technical Report 177:2007, Color Rendering of White LED Light Sources, states, ‘‘The conclusion of the Technical Committee is that the CIE CRI is gen- erally not applicable to predict the color rendering rank order of a set of light sources when white LED light sources are involved in this set. - According to the definition, the color correlated temperature of a light is dif- ferent from the definition of the color of light. - One of the weak points of LEDs is the necessity of heat management. - Incandescent light bulbs convert about 8% of the input electric power into visible light, and the rest is radiated in the form of heat. - V D will be the voltage drop between the two poles of the LED. - V is the voltage of the power supply, as a 9 V battery. - Typically, this is between 1.5 and 4 V depending on the color of the LED. - It radiates on a continuous spectrum but only a small portion of the radiation belongs to the visible range. - Most of the consumed energy is radiated in the form of heat.. - A tungsten filament in its solid state radiates most of the consumed electric power in the infrared region. - Nevertheless fluorescent lamps present a certain number of disadvantages.The first one is its hazardous aspect because of the mercury they contain in the glass envelop that is rather fragile. - Getting the light out of the semiconductor: overcoming total internal reflection and reabsorption.. - 4.3 Principle of operation of the multilayer OLEDs. - The main challenge in the realization of fully transparent devices is the deposition of the top electrode. - Figure 4.17 shows the block diagram of the conventional OLED manufacturing process. - As such, thin film barriers are one of the prerequisites for OLEDs. - The big news in 2009 was the introduction of the first OLED lighting products.. - For a portion of the ceiling (such as in a common office), the needed luminance is near 1,000 cd/m 2 . - The price of the OLED lighting panel per square meter is still high. - As a result, one of the major problems faced by OLED is questionable longevity. - A schematic of the structure is shown in Fig. - b Schematic of the substrate encapsulation of OLED device. - Schematic of the thin film encapsulation is displayed in Fig. - 4.26 Schematic of the thin film encapsulation. - Fig- ure 4.28 shows the schematic of the ink-jet printing. - 4.28 Schematic of the. - However, the understanding of the LED lighting standard and Fig. - Idemitsu Kosan is also diversifying into OLED lighting that takes advantage of the properties of OLEDs as light sources [175].. - A projected roadmap of the applications and technology requirements for OLED Lighting in the next 10 years is displayed in Table 4.12. - Environmental impact associated with the reduction of the need for electricity (less air pollution, depletion of non-renewable sources of energy, less green- house effect).. - They inhale a lot more of the toxic smoke. - In Botswana, more than 70% of the country’s population lives in rural areas. - Alternative energy sources were recognized as a viable solution for the energy needs of the poor (Table 5.5).. - Estimated to be about 30% of the total costs of PV systems.. - Awareness/information Awareness of the applications of solar photovoltaic systems is very low.. - Lack of awareness of the costs and benefits of renewable energy technologies.. - The amount may be of the order of the daily consumption of kerosene fuel.. - Reliability of the solar system to provide uninterrupted electricity is the most important factor for end users.. - Sometimes customers also need to make a part of the down payment. - Solar Lighting for The Base of The Pyramid—Overview of an Emerging Market (2010). - The price of the OLED lighting panel is still very high. - The cost reduction strategy of the OLED lighting panel in 2020 will be:. - Size of the PV Panel