It’s a clear frosty morning here in the upper Ottawa Valley, but even on a cold morning like this, the Sun is flooding the forest with energy. The earth’s tilt this time of year reduces the energy falling on horizontal surfaces, but an object at right angles to the sun’s rays is receiving approximately a thousand joules of energy per second per square metre.
That means that each square metre receives power at the rate of a thousand watts. That is a lot of power. Let’s, see if we can capture some of this device, in my hand, is a photovoltaic cell. The crystal structure of this high-tech piece of equipment is designed to produce electricity when light particularly sunlight shines on it.
Let’s. Take a look at how these things work. If you have watched our video on electricity, you will know that electricity is a flow of electrons charged atomic particles that travel through a conductor from the negative terminal to the positive terminal of a battery.
The battery is a chemical device that produces the force needed to move the electrons in this animation. Electrons are flowing through a lightbulb. Electrical energy is being converted to light energy.
A solar cell acts much like a battery cell when light shines on the surface. Energy is picked up by electrons. They use this energy to move from the negative terminal of the cell through a circuit to the positive terminal of the cell.
Solar cell manufacturers use silicon crystals to create solar cells. Silicon is a very common element. If you have ever found a piece of quartz, you have found a crystal created from silicon and oxygen.
A silicon atom has four valence electrons. This simplified model shows a silicon crystal structure with each silicon atom connected to four others. It turns out that elements like phosphorus and boron can be added to silicon, creating crystals that form the negative and positive layers of a photovoltaic cell.
The negative or n layer of the cell is created when a phosphorus atom, which has five valence electrons, replaces a silicon atom. The fifth electron of the phosphorus atom is weakly bound to the atom.
If this electron picks up some energy, it can move and become electricity that energy can come from late. Similarly, the positive or P layer is created when a boron atom with three valence electrons replaces a silicon atom.
This leaves a positive hole and creates a positive layer that attracts electrons in a complete solar cell. The N and P layers are sandwiched together. The movement of electrons in this configuration is complex, but basically light energizes electrons in the N layer, and they are attracted through a conductor to the positive P layer.
This is electricity. This iridescent blue site is the negative layer of this cell. The thin metal bar is embedded in the surface, provide a conductive path for the electrons. This cell has a black wire connected to the metal bars.
This is the negative terminal. The positive terminal is the back of the cell. It is covered in a metallic sheet connecting the negative probe of a voltmeter to the black lead and then touching the positive probe to the back of the cell.
We get an open circuit voltage. Reading a single cell like this will produce point five volts in direct sunlight today, the sun shining through an open door, is giving us between 0.45 and point four eight volts, the short-circuit current output of a cell.
This size is small. Today I’m. Getting less than 50 milliamps to produce higher voltages and currents, it is necessary to connect multiple cells in series and parallel. The large cells used in commercial installations are created by assembling multiple single cells into a panel.
As I mentioned at the beginning, the Sun floods, the earth, with about 1000 watts of power per square meter commonly available solar cells, convert about 10 % of this energy into electricity. But researchers are currently working on a new generation of solar cells capable of converting over 40 % of the sun’s, energy to electricity.
This exciting green technology will soon be contributing significantly to our power needs to learn more about electricity and energy. From the Sun visit our website hila Road calm, you
