INTRODUCTION :

Working principle:
The Photovoltaic (PV) cell is composed of at least two layers of the semiconductors which have been “doped” with different impurities. This makes an excess of free electrons (n-type) on one side of the junction, and a lack of free electrons (p-type) on another side. When the photovoltaic cells are irradiated with sunlight, some photons are reflected and the others are absorbed by the solar cell. When the photovoltaic cells keep enough photons, the negative electrons are released from the semiconductor material. Due to the manufacturing process of the positive layer, these free electrons naturally migrate to the positive layer which creates voltage differential. When the solar cell is connected with the external load, there will be a current circulation in the circuit. Each single solar energy cell produces only 1-2 watts. In order to increase output power, these cells (from one to several thousands) are connected in series or in parallel with others, what is called a solar array.
Using the requirements:
Solar panel
Wooden board
LDR (Light Dependent Resistor) sensors-1
4 v.lead acid battery-1
Circuit board (555 TIMER IC)
LED (Light Emitting Diode) lights-7
ON/OFF switch-1
Wires
Cool drink straws-6
Block color chart
Fevikwik+glow sticks+others
LDR Working Principle:
Working Principle of LDR. This resistor works on the principle of photo conductivity. It is nothing but, when the light falls on its surface, then the material conductivity reduces and also the electrons in the valence band of the device are excited to the conduction band.
Solar panel working principle:
They work on the principle of the photovoltaic effect. When certain materials are exposed to light, they absorb photons and release free electrons. ... Based on the principle of photovoltaic effect, solar cells or photovoltaic cells are made. They convert sunlight into direct current (DC) electricity.