Solar Energy Essay

Problem Summary And Introduction

Today solar energy is seen as the most reliable renewable energy source. According to calculations the sun deposits 120,000 TW of radiation on the surface of Earth. The sun covers about 0.16% of the land on Earth. With 10% efficient solar conversion systems we can generate almost 20 TW of power, which is almost twice the world’s consumption. The above comparisons show that solar energy have impressive magnitude, it provides more energy than present day human technology can provide.

The first solar cell were developed about 50 years ago by Bell Laboratories in 1954. These solar cells were used as power source in satellites. In the end of 1970 scientists were able to develop silicon solar cells (Photo voltaic

Its resistance decreases as the intensity of light falling on it increases. This property is used for locating the position of the sun. In LDR based solar tracking systems, three or more sensors are arranged in different ways to locate the position of the sun. One of the most common methods are placing 3 LDR sensors at three ends of the panel. Another method makes use of formation of shadows by change in position of sun to locate its current position. Generally 4 LDR sensors are placed closed together separated by dark partitions, with one LDR sensor in each partition. The readings obtained from different LDR sensors are compared to determine the relative illuminance and hence find the position of sun relative to the panel. This data is fed to a micro-controller that computes the difference and signals the actuators to align the panel. This method of tracking the sun is inexpensive and relatively simple. LDR based trackers have a positional feedback system which keeps a regular check on the current position of the panel. The disadvantage of this method is that it’s not very accurate in cloudy of foggy weather. The system tends to enter hunting mode which results in substantial consumption of