ELA Component

Our project is about solar panels. We are going to build a solar panel machine that converts energy from the sun into electrical energy. We chose this project because we wanted to see how much energy the solar panel can generate over a day. We are going to keep journal entries over the duration of the project. We chose to keep a journal because it would allow everyone to see the changes we have to make to the original procedure to finish the solar panel machine.

11/03/13:

Photovoltic cells are made of special materials called semiconductors such as silicon, which is currently used most commonly. Basically, when light strikes the cell, a certain portion of it is absorbed within the semiconductor material. This means that the energy of the absorbed light is transferred to the semiconductor. The energy knocks electrons loose, allowing them to flow freely.

11/18/13:

Depending on construction, photovoltaic modules can produce electricity from a range of frequencies of light, but usually cannot cover the entire solar range (specifically ultraviolet, infrared and low or diffused light). Hence much of the incident sunlight energy is wasted by solar modules, and they can give far higher efficiencies if illuminated with monochromatic light. Therefore, another design concept is to split the light into different wavelength ranges and direct the beams onto different cells tuned to those ranges. This has been projected to be capable of raising efficiency by 50%.

12/05/13:

Silicon has some special chemical properties, especially in its crystalline form. An atom of silicon has 14 electrons, arranged in three different shells. The first two shells - which hold two and eight electrons respectively - are completely full. The outer shell, however, is only half full with just four electrons. A silicon atom will always look for ways to fill up its last shell, and to do this, it will share electrons with four nearby atoms. Its like each atom holds hands with its neighbors. except that in this case, each atom has four hands joined to four neighbors. That's what forms the crystalline structure, and that structure turns out to be important to this type of PV cell.

12/27/13:

When light, in the form of photos, hits our solar cell, its energy breaks apart electron-hole pairs. Each photon with enough energy will normally free exactly one electron, result in a free hole as well. If this happens close enough to the electric field, or if the free electron or free hole happens to wander into its range of influence, the field will send the electron to the N side and the hole to the P side. This causes further disruption of electrical neutrality, and if we provide an external current path, electrons will flow through the path to the P side to unite with holes that the electric field's sent there, doing work for us along the way. The electron flow provides the current, and the cell's electric field causes a voltage. With both current and voltage, we have power, which is the product of the two.

01/04/14:

Light can be seperated into different wavelengths, which we can see in the form of a rainbow. Since the light that hits our cell has photons of a wide range of energies, it turns out that some of them won't have enough energy to alter an electron-hole pair. They'll simply pass through the cell as if it were transparent. Still other photons have too much energy. Only a certain amount of energy, measured in electron volts and defined by out cell material, is required to knock and electron loose. We call this the band gap energy of a material.

01/21/14:

Solar panels are made of solar cells. A cell is a small disk of semiconductor like silicon. They are attached by wire to a circuit. As light strikes the semiconductor, light is converted into electricity that flows through the circuit. As soon as the light is removed, the solar cell stops producing power.