WO2010058279A1

WO2010058279A1 - Photovoltaic cell generator unit

Info

Publication number: WO2010058279A1
Application number: PCT/IB2009/007522
Authority: WO
Inventors: Giacomo Carcangiu; Karen Lesley Buckett
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-11-20
Filing date: 2009-11-20
Publication date: 2010-05-27
Anticipated expiration: 2011-05-20
Also published as: ITTO20080859A1

Abstract

In a photovoltaic cell generator unit (1), a parabolic body (5) having a reflecting parabolic surface (6) is carried by a support arm (2) and generates a light beam having an optical axis thereof converging towards a photovoltaic device (10) having at least one photovoltaic cell (9a) and an input body (12) of the light beam arranged facing the reflecting parabolic body (5) along the optical axis of the light beam itself.

Description

PHOTOVOLTAIC CELL GENERATOR UNIT

TECHNICAL FIELD

The present invention relates to a photovoltaic cell generator unit.

BACKGROUND ART

The use of photovoltaic solar panels, either directly exposed to sun light or onto which the sun light itself is directed by means of appropriately oriented flat mirror bodies, is known in the field of production of electric and thermal energy by means of photovoltaic cells.

The extensions of the known photovoltaic solar panels are proportional to the amount of energy to be produced, and in general, except for particularly low powers, the extensions of the known photovoltaic solar panels are normally considerable, of even several square meters. Their use is thus subordinated to the availability of considerable spaces which are difficult to be found, especially in urban environments, unless by exploiting roofs and side paneling of buildings. In all cases, once the practical installation difficulties consequent to the aforesaid distribution have been overcome, the known solar panels are often difficult to be reached for normal inspection and maintenance operations .

In addition to the above, the known solar panels often imply problems of environmental impact.

From a constructional point of view, the known photovoltaic solar panels have, instead, relatively high costs which may be ascribed, on one hand, to the considerable number of photovoltaic cells used, i.e. to the considerable extension of the photovoltaic incidence surface of the solar rays, and on the other hand, to the costs for assembling and electrically connecting the photovoltaic cells to one another. DISCLOSURE OF INVENTION

It is the object of the present invention to provide a photovoltaic cell generator unit which allows to simply and cost-effectively solve the above-mentioned problems and which, in particular, is simple and cost- effective to be manufactured, in addition to being compact and quick to be installed and maintained.

According to the present invention, a photovoltaic cell generator unit is provided as claimed in claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described with reference to the accompanying drawings which illustrate a non- limitative embodiment thereof, in which: figure 1 is a perspective view of a preferred embodiment of the photovoltaic cell generator unit according to the present invention; figure 2 shows a detail of figure 1 on an enlarged scale; figure 3 shows a perspective view of a component of the detail in figure 2; figure 4 is a figure similar to figure 1 and shows a variant of a detail in figure 1; and figure 5 shows a detail of figure 4 on enlarged scale.

BEST MODE FOR CARRYING OUT THE INVENTION

In figure 1, numeral 1 indicates a parabolic photovoltaic cell generator unit comprising a support structure 2, in turn comprising an attachment plate 3 and a support arm 4 extending upwards from the plate 3 itself. Unit 1 further comprises a parabolic body 5, which is connected to an upper end of the arm 4, is comparably dimensioned as the traditional parabolic bodies for domestic use for receiving satellite signals, in the specific described example, and is frontally delimited by a conveniently chrome-plated, parabolic mirror surface 6, adapted to generate a light beam having an optical axis converging in a focal point. With specific reference to figure 1, the front surface 6 consists of a plurality of flat portions 6a arranged side by side and each peripherally delimited by a respective broken line.

Again with reference to figure 1, unit 1 further comprises a further support arm 8, which overhangingly extends from a peripheral edge of the parabolic body 5 and supports a photovoltaic cell device 10. With reference to figure 1 and in particular to figure 2, device 10 comprises a tubular body 11 connected to one end of the arm 8 in a position facing the parabolic surface 6 and crossed by the mentioned optical axis. The tubular body 11 has an end inlet portion 12 for the light beam 6 fluid-tightly closed by a plate or screen 13 permeable to light, and an opposite end portion 15, also fluid-tightly sealed by means of an annular disc 16 (figures 2 and 3) housed in the terminal portion 15. Opening 18 (figure 3) of the annular disc 16 is closed, again fluid-tightly, by a flat support or reference plate 19, which in the particular described example, carries a single photovoltaic cell 19a. Conveniently, cell 19a has a rectangular shape and a flat photovoltaic incidence surface of the mentioned light beam, the extension of which may be of a few square millimetres for high light concentrations and is however variable according to needs. In all cases, the ratio of the photovoltaic surface with the parabolic surface 6 is always lower than one. The flat photovoltaic surface preferably extends orthogonally to the axis of the light beam in a position by the side of the focusing point of the light beam itself, and conveniently in a position such that the focusing point either lays on the photovoltaic surface of incidence or is arranged on the opposite side of the photovoltaic surface of incidence itself with respect to the parabolic body 5. The photovoltaic cell 19a is electrically connected to an electric wiring comprising two cylindrical electric contacts 21 protruding outwards from the tubular body 11 through the annular disc 16. Tubular body 11, annular disc 16 combined with plate 19 with the photovoltaic cell 19a, and plate 13 form part of the device 10 and delimit a sealed chamber 22 therebetween (figure 2), which houses an electrically insulating, cooling liquid moved along a cooling circuit 23 (diagrammatically shown) , through an inlet opening 24 and an outlet opening 25 obtained through the portion 15.

The liquid used has a crystalline appearance and is a silicone liquid, and preferably polydimethylsilicone liquid. Conveniently, the liquid used is known under the trade name of "DOW CORNING® 561". Such a liquid has a viscosity at 25° centigrade from 40 to 60 mm²/s, a thermal conductivity in the range from 0.10 to 0.20 W| (mK) , and a fire point higher than 300⁰C. Furthermore, the liquid has a combustion temperature in the range from 350° to 400° centigrade, a volume resistivity at 25°C of 1.0x1014 ohm. cm, a dissipation factor at 25° and 50 Hz in the range from 0.00009 to 0.00015, and a refraction index at 25° in the range from 1.35 to 1.45. The liquid commercially known under the trade name of "DOW CORNING® 561" has a high transfer efficiency, especially because it associates a crystalline appearance and, thus, a high light permeability, with a high thermal stability. Parallelly, the polydimethylsilicone liquids - and in particular the "DOW CORNING® 561" liquid - have a resistance to solar ray exposure which is not only high but substantially does not change over time, excellent convention abilities, are neither polluting nor toxic and thus safe for humans and the environment whether for any reason they are dispersed in the external environment or inhaled. The above-mentioned liquids are especially neither aggressive nor corrosive, whereby do not impose limitations upon the choice of materials to be used to manufacture the sealed chamber where they are housed. Moreover, the aforesaid liquids do not require particular contrivances in terms of geometry and/or over-dimensioning of the parts made of these materials.

In use, the light beam generated from surface 6a directly impacts the surface of the photovoltaic cell 19a which, in response and in a known manner, generates electric power fed through the electric contacts 21 and heat transferred outwards by means of the cooling circuit 23 and recovered in a known manner.

In the variant shown in figure 4, the tubular body 11 in conjunction with the cooling circuit 23, the disc 16 in conjunction with the plate 19 and the corresponding cooling circuit are arranged in a remote position with respect to the parabolic body 5, in the particular described example close to the base 3, or according to a variant (not shown) , in a position spaced both from the base 3 and from the parabolic body 5, so as to be easily reachable by a person in charge of inspecting and maintaining. In such a configuration, device 10 comprises a transfer unit 30 for the light energy, which unit is interposed between the arm 8 and the tubular body 11.

The transfer unit 30 comprises a funnel-shaped inlet body 31 for the light beam, connected in a fixed position to one end of the arm 8 so as to be intersected by the optical axis. With reference to figure 5, the funnel-shaped body 31 is fluid-tightly closed on the side facing the parabolic body 5 by means of a light permeable screen 32 and has an outlet collar 33 again fluid-tightly connected to an end portion of an either rigid or flexible piping 34. In the described example, piping 34 has a constant section and comprises a curve segment and a rectilinear segment. Piping 34 is either made of plastic, metal or composite material and has a side wall which is impermeable to light and a conveniently chrome-plated, inner reflecting surface.

According to a variant (not shown) , piping 34 has a plurality of rectilinear segments intercalated with curved segments.

An opposite end portion of piping 34 is fluid- tightly connected to the portion 12 by means of a further portion 35. Portion 35 is an extension of the tubular body 11 beyond the screen 13 and is firmly connected to the fluid-tight portion 12 for defining, along with piping 34 and body 31, an elongated chamber 38 filled with a light energy transfer liquid which is, preferably but not necessarily, identical to the fluid crossing the chamber 22. In the particular described example, the two liquids are separated from each other by the screen 13. According to a variant, device 10 is free from the screen 13 and, therefore, the same liquid fills the elongated chamber 38, the chamber 22 and the cooling circuit 23.

From the above, it is apparent that because the incident light on the photovoltaic cells is not of natural intensity, as in the known solutions, but of high intensity due to the focusing caused by the parabolic surface 6, the amount of energy per surface unit produced by the photovoltaic cell 19a is much higher than that produced by the photovoltaic cells of the traditional photovoltaic panels. In the specific case, it has been experimentally found that the in the described unit 1 a photovoltaic surface of a few square millimeters produces the same energy produced by a traditional photovoltaic panel having a photovoltaic surface of over one square meter. It has further been experimentally found that the above result may be obtained both in the case of the solution in figure 1, i.e. with the photovoltaic cell directly illuminated by the light beam, and in the case of figure 4 where the light radiation is moved to a remote position by means of the transfer unit 30. The constructional features of the unit 30 indeed allow to firstly transfer the light radiation under conditions of substantial absence of losses because the piping 34 and the bodies 31 and 35 are impermeable to light, but especially allow to arbitrarily choose the movement path. The above essentially results from the use of the particular described liquid, which precisely for its chemical- physical features has been revealed as being an excellent transfer medium for light waves. Specifically, the liquid used allows to transfer a light beam inputting to any output location following any feeding path and under conditions of substantial absence of losses. Indeed, according to the invention, the piping may be freely shaped according to the needs of the path, being in practice a common piping for liquids, and the liquid contained therein poses no limits to the geometric choices and to the section/variation of section of the same piping because it simply fits the space inside the piping. Furthermore, the liquid used is substantially insensitive to thermal variations, whereby it may be used to connect environments at even very different temperatures.

For the preceding reasons, the delivered energy being equal, the described unit 1 allows to drastically reduce the photovoltaic surface of incidence of the light beam and consequently the overall dimensions as compared to the existing solutions, and makes it possible to install photovoltaic apparatuses in zones and positions in which the traditional photovoltaic panels could not be positioned, both due to lack of space and problems of environmental impact. Not only, but precisely because of the small size with the delivered energy being equal, the described unit 1 may be arranged in easily reachable positions, thus eliminating the known practical difficulties of installation and considerably facilitating the normal inspection and routine maintenance operations . The inspection and maintenance operations are further facilitated if the photovoltaic cell is arranged in a remote position with respect to the parabolic body 5, i.e. if the liquid transfer device 30 is used. Under such a condition, indeed, the photovoltaic cell may be arranged in any position by exploiting the piping flexibility and/or the fact that curved segments may be intercalated with rectilinear segments without any limitation to predetermined paths.

In addition to the above, it is worth noting that small photovoltaic surfaces of incidence of the light rays immediately translate into a drastic reduction of the manufacturing costs, the number of photovoltaic cells used being greatly reduced, which photovoltaic cells are expensive per se precisely due to the particular materials used for manufacturing them, and the costs for assembling or electrically connecting the photovoltaic cells to one another are also reduced.

From the above it is apparent that changes and variations may be made to the described unit without departing from the scope of protection defined by the claims. In particular, the photovoltaic cell device 10 may comprise more than one photovoltaic cell of shape and size either equal to or different from those described by way of example. In particular, the flat photovoltaic cell 16 may be replaced with curved photovoltaic cells or be associated with curved photovoltaic cells adapted to pick up possible reflected rays. In the latter case, the photovoltaic cells would either partially or completely cover both the disc 16 and the inner side walls of the tubular body 12.

Claims

1. A photovoltaic cell generator unit comprising a support arm, a photovoltaic cell device carried by said support arm and comprising at least one photovoltaic surface of incidence of a light radiation, a parabolic reflecting body carried by said support arm and generating a light beam having an optical axis thereof converging in a focal point, said photovoltaic cell device comprising inlet means for said light beam arranged in a position facing said parabolic body and along said optical axis and a cooling circuit of said photovoltaic cell device; said cooling circuit using an electrically insulating, cooling liquid and said photovoltaic cell being at least partially immersed in said electrically insulating, cooling liquid.

2.- The unit according to claim 1, characterized in that said input means are supported by a second arm protruding from a peripheral edge of said parabolic body.

3.- The unit according to claim 1 or 2, characterized in that said photovoltaic surface of incidence extends within said input means in a position adjacent to said focal point.

4.- The unit according to claim 3, characterized in that said photovoltaic surface of incidence extends at least partially perpendicularly to said optical axis.

5.- The unit according to claim 1 or 2, characterized in that said photovoltaic surface of incidence extends within said input means and in that said focal point lies on said photovoltaic surface of incidence.

6.- The unit according to claim 1 or 2, characterized in that said photovoltaic surface of incidence extends in a remote position with respect to said input means; said photovoltaic cell device further comprising light wave transfer means interposed between said input means and said photovoltaic surface of incidence; said transfer means comprising a transfer means permeable to light in a liquid or gel form.

7.- The unit according to claim 6, characterized in that said transfer means permeable to light is a silicone liquid.

8.- The unit according to claim 6 or 7, characterized in that said transfer means permeable to light is a polydimethylsilicone liquid.

9.- The unit according to one of claims 7 or 8, characterized in that said silicone liquid has a thermal conductivity in the range between 0,10 and 0.20 w| (mK) .

10.- The unit according to one of claims 7 or 8, characterized in that said silicone liquid has a dissipation factor in the range between 0.00009 and 0.00015 at 25° and 50 Hz.

11.- The unit according to any of claims 6 to 9, characterized in that said transfer means comprise a closed piping on one side, by said input means and, on the other side, at least partially by said photovoltaic surface of incidence; said piping housing said light transfer means.

12.- The unit according to claim 10, characterized in that said piping is flexible in order to follow an at least partially curved path.

13.- The unit according to claim 10 or 11, characterized in that said liquid light transfer means and said electrically insulating and cooling liquid are separate from one another.

14.- The unit according to claim 10 or 11, characterized in that said transfer means comprise a piping hydraulically communicating with said cooling circuit and use a silicone or polymethylsilicone liquid in common with said cooling circuit.

15.- The unit according to any one of the preceding claims, characterized in that said photovoltaic cell at least partially delimits a chamber housing at least part of said electrically insulating, cooling liquid.