Batteries: thermoelectric and photoelectric – Photoelectric – Panel or array
Patent
1996-09-24
1997-08-26
Weisstuch, Aaron
Batteries: thermoelectric and photoelectric
Photoelectric
Panel or array
136256, H01L 3105
Patent
active
056606435
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
Solar cell installations are a model of environmental compatibility: in service they generate neither emissions, waste heat nor noise. The technical potential of solar cell installations for the generation of power is very considerable throughout the world. They can be applied practically anywhere and for any purpose, such as the decentralized supply of energy to remote settlements, centralized power generation in solar-powered vehicles.
The extent to which the potential of solar cells can be realized is largely dependent on whether the development of solar cells leads to cheaper manufacturing processes--if this proves to be the case, it is conceivable that a significant proportion of power generation may be met with solar cells, even in the industrialized nations with their low amounts of sunshine.
Ways and means of lowering the manufacturing costs of solar cells have accordingly been sought.
Solar cells are based on the so-called photo-voltaic effect. Sunlight is capable of liberating charge carriers which can be separated at the interface between two different semiconductors, so that an electrical voltage is produced. Its detailed mechanism is as follows.
Where an electron conducting or n-type semiconductor (e.g. silicon doped with trace amount of phosphorus) is situated adjacent to a hole conducting or p-type semiconductor (e.g. silicon doped with trace amounts of boron), an internal electrical field is produced in the boundary zone, i.e. the p-n transition. Negatively charged electrons migrate from the n-semiconductor to the p-semiconductor, and holes (positively charged sites not occupied by electrons) from the p-semiconductor to the n-semiconductor, in order to compensate for the charge gradient at the interface. If light, e.g. solar radiation, is now absorbed by the semiconductor, it causes pairs of electrons and holes to be released on both sides of the interface. Under the influence of the internal field, the electrons collect in the n-type semiconductor, and the holes in the p-type semiconductor, causing a photoelectric voltage equal and opposite to the internal field to occur between the two sides. Contacts can be used to tap this photoelectric voltage and supply it to an external circuit. The current intensity increases with the intensity of illumination and the size of the illuminated area. The voltage is dependent on the semiconductor materials. Commercial crystalline silicon solar cells measure up to 10 cm.times.10 cm and produce a voltage of approximately 0.5 volt and a peak power output of 1 watt. Higher voltages and power outputs are required, however, in solar cell installations. According to the prior art, manufacturers connect several solar cells one after the other in series and encapsulate them under glass in a weatherproof fashion to produce a solar module, in the form of a replaceable unit. A solar cell generator can be made by connecting together one or more modules in series or in parallel to provide the desired voltage or power output. According to the crystalline form of the semiconductor, it is possible to distinguish between three basic types of solar cells, with silicon being the predominant semiconductor material.
There are what are known as monocrystalline solar cells. Their manufacture involves drawing a p-type silicon monocrystal ingot from a molten silicon mass and slicing it into wafers of about 0.4 mm in thickness. The front face directed towards the solar radiation is doped by the diffusion of, for example, an n-type dopant, e.g. phosphorus, with a thickness of three to four microns to produce the p-n transition that is critical for the principle to function. Metal contacts for collecting the current are vacuum-metallized on both faces. In the case of the front face, this is in the form of a lattice covering not more than 10 per cent of the surface area so as to permit the transmission of the greatest possible amount of solar radiation. The largest crystals or wafers have a diameter of approx. 15 cm.
The individual solar cells are connec
REFERENCES:
patent: 4217633 (1980-08-01), Evans, Jr.
patent: 4789641 (1988-12-01), Inuzuka
patent: 4980574 (1990-12-01), Cirrito
patent: 5268037 (1993-12-01), Glatfelter
patent: 5296043 (1994-03-01), Kawakami et al.
patent: 5421908 (1995-06-01), Yoshida et al.
Hlusuisse Technology & Management Ltd.
Weisstuch Aaron
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