Photovoltaic Cells

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Photovoltaic cells are made using the same materials used to make semiconductors, such as silicon.
The cell converts solar energy into electricity using the photovoltaic or Hertz effect. The term solar cell is used for cells made specifically for capturing energy from the sun and referred to as a ‘photovoltaic cell’ when the source is not defined.

Cells have developed in three waves, called ‘generations’ in the industry. The first generation cells feature large-area, single junction systems. First generation devices still represent the majority of this type of equipment available on the market.
The second and third generations feature newer technology, but have yet to prove themselves on the market.

Second generation devices feature several successful materials: cadmium telluride (CdTe), copper indium gallium selenide (CIGS), and amorphous and micromorphous silicon applied as a thin film onto a supporting medium.

Third generation systems are still highly experimental and in the research and development stage. Innovations include non-silicon-based cells using materials such as nanocrystalline, polymer, and dye-sensitized cells. Also, third generation cells won’t need the p-n junction needed by traditional, silicon-based semiconductors.

Photovoltaic cells are just the smallest part of these incredible technologies.
Groupings of cells are used to make solar modules, solar panels or photovoltaic arrays. Cells are fit together to form modules. Modules are then wired together, parallel or in series, to form a solar array.

In the case of solar cells, an electric field is formed by a thin semiconductor wafer that has been specially treated to form a positive field on one side and a negative field on the other. When light (energy) hits the solar cell, the semiconductor material comes alive – electrons are knocked loose from the atoms inside. Electrical conductors can then be attached to the positive and negative sides. These form an electrical circuit. Now those electrons are captured in the form of an electric current – electricity has been generated and can now be converted, used or distributed.

The larger the solar array, the more energy can be generated. Arrays and modules can be wired in series or parallel to achieve any combination of current and voltage. In its raw state, the energy collected by photovoltaic cells is in the form of direct current (DC).Grid tie-in solar power systems include convertors that reformat the DC to alternating current (AC).

Solar cell absorption rates keep getting better and better. Scientists have already closed in on a near-perfect system of layered anti-reflective coating that boosts the sunlight-absorption rates from 67.4 to 96.21 percent. Additionally the new coating is reported to be applicable to just about any photovoltaic material.

Due to past inefficiencies in absorption rates, solar arrays had to be mounted on south-facing roofs at a calculated angle to make sure the cells were in the best position or live in a certain area that receives a certain amount of sunlight each year. The latest anti-reflective coating might change all of that.

With all of the positive research in the fields of nanostructure photonics and photonic crystals it won’t be long before someone’s lab experiment makes it to the market – the most efficient and least expensive solar cell is yet to come.