02/03/2014 - 16:24
Renewable Energy Development Institute - REDI

The term „photovoltaics” comes from two words – „photo” meaning light and “voltaic” meaning the method of generating electricity. Photovoltaic cells are used to convert sun energy into electricity; the process is called photovoltaic conversion. The history of photovoltaics dates back to the 19th century when a French scientist – Bequerel discovered the photovoltaic effect. The first photovoltaic cell was made of semiconducting selenium plate coated with a thin gold layer.

All the living organisms create and consume energy during internal metabolic processes. Most of the renewable energy resources are some forms of energy coming from the sun, primarily deriving from sunlight. All the kinds of fossil fuel are non-renewable energy resources. Renewability of energy resources is typically understood as the ability to recreate the energy resources in a period of time comparable to the human life span. Nowadays, solar energy (helioenergy) is still hardly used.

Solar cells (photovoltaic cells, photoelectric cells) are the semiconducting materials (crystalline substances whose electrical conduction can be changed in a wide spectrum – e.g. 10-8 to 103 S per cm – by doping, heating, illuminating, or other actions) which convert solar energy into electric energy thanks to the photovoltaic effect.

Photovoltaic cell is a silicon-made semiconducting plate, inside of which electric field is created by a p-n junction. The rays of sunlight shine upon the photovoltaic cell, which emits electrons from their holes in the semiconductor’s structure, thus creating pairs of opposite ions. Then their electric charge is divided by p-n junction-created electric field, therefore forming potential difference. When we connect a capacitor, electric current starts to flow.

Solar wafers are made of semiconducting materials, such as silicon (Si), germanium (Ge), selenium (Se). By connecting solar wafers, solar cells are created. There are different cells produced from a various number of wafers, accordingly to their employ and quality.

Solar cells are used i.a. in solar power plants, calculators, watches, artificial satellites, hybrid cars, garden lamps, traffic signs backlight, charging battery during the daytime and using their energy in the nighttime e.g. on yachts. The solar cell market is still young and steadily developing.

In April 2012 scientists from Austria and Japan created solar cells characterized by thickness of only 1.9 micrometer. It’s ten times less than the thinnest currently available appliances of this kind. These solar cells will come into use within 5 years.

The market of photovoltaic cells is growing every year even by several dozen per cent. The world leaders of solar cells production are China and Europe.

  • Bregus P6-60, Polycrystalline PV module 60 cells, 245-265 W
  • Bregus P6-72 Polycrystalline PV module 72 cells, 295-315 W

People are forever trying to find new sources of renewable energy, so it isn’t surprising that they are especially interested in water and its versatility. Accordingly, much effort has been directed into obtaining energy from tidal and wave power, which are defined as circular movements of water molecules caused by wind that moves water surface through friction.