Indirect Lighting & Energy Conservation Part 3

Category: Environment & Green Technology Published: Monday, 25 April 2016

2. TECHNOLOGIES AVAILABLE FOR INDIRECT LIGHTING 

2.1 PHOTOVOLTAICS : 

In the 1970s, a serious effort began to produce photovoltaic panels that could provide cheaper solar power. The three basic types of solar cells are single crystal, polycrystalline, and amorphous. 

The electricity (direct current) (DC) generated from these solar cells is stored in a battery. Between the battery and the loads, charge controllers or electronics are provided. These prevent the overcharging or discharging of batteries by regulating the flow of electricity. Compact fluorescent lamps (CFLs) are normally used as lighting loads. Other loads are electrical devices that operate on DC or alternating current (AC). In case of AC loads, inverters are used. 

1.1.a ENERGY : 

PV systems have also certain limitations. One of the major drawbacks of a PV system is its high capital cost. This high capital cost makes the system cost-prohibitive. Further, only a few types of electrical devices can be operated using PV, as the nature of electricity is DC. This result in PV systems being less competitive compared to other alternative sources of electricity such as diesel or kerosene generators and battery inverter. Diesel/kerosene generators and battery inverters require similar investments, but are compatible with a wide range of electric devices. Expect for the PV panel, the life of the system components is limited. The cost of PV panels is also coming down drastically due to advances in these semiconductor technology, manufacturing process and the annual production rate. On the other hand the conventional energy price is increasing multifold for the last two decades. It is therefore necessary to use new technologies like LED’s not only to reduce power requirement but also increase the life of the system components. 

2.2 LIGHT EMITTING DIODES (LED):

 LED's are special diodes that emit light when connected in a circuit. They are frequently used as "pilot" lights in electronic appliances to indicate whether the circuit is closed or not. A a clear (or often colored) epoxy case enclosed the heart The two wires extending below the LED epoxy enclosure, or the "bulb" indicate how the LED should be connected into a circuit. The negative side of an LED lead is indicated in two ways: 1) by the flat side of the bulb, and 2) by the shorter of the two wires extending from the LED. The negative lead should be connected to the negative terminal of a battery. LED's operate at relative low voltages between about 1 and 4 volts, and draw currents between about 10 and 40 milliamperes. Voltages and currents substantially above these values can melt a LED chip. 

2.3 FRESNEL LENS :

 The Fresnel lens was invented by French Physicist Augustin Jean Fresnel, who first used this design to build a glass lighthouse lens in 1822. The Fresnel lens is a thin, flat optical lens which consists of a series of small narrow concentric grooves on the surface of a lightweight plastic sheet in order to reduce the thickness, weight and cost. Each groove is at a slightly different angle than the next and with the same focal length in order to focus the light toward a central focal point. Every groove can be considered as an individual small lens to bend parallel light waves and focus the light. The fresnel lens is a good solution for quality image and efficiency at a significantly lower cost. The fresnel lens is usually corrected for spherical aberration. The applications for Fresnel lenses include lighting, lighthouse, overhead projector, fresnel magnifier, TV projection, condenser system, camera spotlight, automobile headlight, solar energy, rear projection, passive motion detector, traffic sign, solar concentrator, collimator, and LED.