Solar Radiation and Energy

Solar panels can be used in calculators and battery operated toys, in satellites and Mars probes to provide them with energy to function in outer space by using the Sun's rays, can be used in traffic signals etc.

Solar constant is defined as the mean amount of the solar energy received by the Earth's atmosphere, per unit of the area, during the time when the Earth is at the mean distance from the Sun. Solar constant equals to 1388 watts per square meter.

Solar cells are devices that converts Sun's radiation energy into electricity. Solar cells contains a semiconductor. Silicon is a good semiconductor that can be used for the production of solar cells.

A solar water heater cannot be used to get hot water on a cloudy day as there is no Sun which is necessary for the working of solar water heater.

In parabolic solar cooker, the container of cooking is placed at the focal point of mirror so that all rays that are falling on solar cooker can converge to one point and produce large amount of heat energy.

The device used in traffic signal lights is Solar traffic light. are signalling devices powered by solar panels positioned at road intersections, pedestrian crossings and other locations to control the flows of traffic. 

Solar cells are made of semiconductor materials like silicon, gallium, or germanium. Platinum is a metal and is not a semiconductor, so it cannot be used to make a solar cell.

Solar cell use light energy from photons (basic unit of light energy) and convert it to electricity using semiconductor physics.

A solar cell converts light energy into electrical energy.

Photovoltaic cells, commonly known as solar cells, convert light energy directly into electricity. They utilize the photovoltaic effect to generate current when exposed to solar radiation.

Output of solar cell occurs at a constant voltage. Using a group of solar cells in the solar panel increases the amount of current produced. Also, as area is increased more solar energy is captured and more electrical energy is produced.

When solar radiation enters the atmosphere, it is absorbed by the clouds and gases and heats the earth's surface. The earth, in return, reflects some of this heat into the atmosphere as infrared radiation. Most of this infrared radiation gets absorbed by atmospheric gases such as carbon dioxide, methane, nitrous oxide, and ozone, commonly known as greenhouse gases. These gases send the infrared radiation back to the earth's surface, thereby heating the surface again. This cycle repeats several times, thereby resulting in the greenhouse effect.

The gases in the troposphere of the atmosphere absorb the sun radiations and trap them so that they do not reflect back. This process allows the heat to remain trapped with in the atmosphere and the earth surface remains warm. This process is called greenhouse effect and the absorbed radiations striking the earth's surface are called green house flux. Carbon dioxide, water vapour, oxides of nitrogen are useful for this purpose. 

In an ecosystem, energy enters from the sun as solar energy and is converted into chemical energy by producers, but the primary source driving the entire flow is solar radiation.