Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
  • H01L31/042—PV modules or arrays of single PV cells
  • H01L31/05—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells
  • H01L31/0504—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/50—Photovoltaic [PV] energy

Definitions

• the present invention relates to a photovoltaic module using light emitting diodes.
• the light emitting diodes are semiconductor devices in which the passage of a current or the presence of a voltage causes an optical radiation.
• the emission may fall in different bands of the spectrum of light radiation; for example, if the material is zinc- doped gallium arsenide, the emitted light is infrared, if the material is gal lium( phosphide doped with silicon and zinc, the emitted light is green, if the material is gallium phosphide doped with oxygen and zinc, the emitted light is red.
• the LEDs are junction diodes and their operation is based on the fact that in a PN junction, at the time of the phenomenon of recombination, the minority carriers give a part of their energy, causing an optical radiation.
• the photovoltaic or solar cells are essentially a PN junction with a large surface area.
• the solar cell includes an N-type material, generall silicon, combined with the P-type material being thicker than the N-type material, with a depletion zone being interposed, and a rear electrical contact.
• an electron moves creating a free electron and a( hole.
• the free electron leaves the N-type material, because it is attracted by the positive charge of the P-type material and advances along the external connection so that an electrical current flow is created.
• the hole is attracted by the negative charge of the N-type material and migrates to the rear electrical contact.
• the electron enters the P-type material from the rear electrical contact it combines with the hole by restoring the electrical neutrality.
• the LED can be operated as solar cells and not as light emitters, although with lower efficiency due to their small size compared to those of the photovoltaic cells. For this reason, in the past, the LEDs have not been used as photovoltaic cells. In fact, if the LEDs are inserted in a module in a small quantity, they do not give an appreciable yield because the performance of each individual LED in terms of current produced is very low. However, if rows of a large number of series-connected groups of LEDs are arranged ⁇ in parallel, each row causes a peak current to be achieved that determines the ignition of the LEDs and. therefore, the emission outside of the light energy caused by the passage of the current, achieving an opposite result to the one intended. Moreover, the absorption of solar energy in the whole spectrum of the light would be excessive for a correct operation of a photovoltaic module that uses a very large number of LE s.
• the photovoltaic module includes LEDs arranged in rows, the LEDs being electrically connected in series and divided in each row into groups that are separated from each other by a device adapted to limit current peaks capable in order to prevent the ignition of the LEDs in successive groups.
• the rows of LEDs are mutually connected in parallel at their ends
• EP 15 1 1086 describes a printed circuit using an array of LEDs in du e to solar cel ls. However, this serves to construct a panel for the light emission surface rather than for the absorption of sunlight and the transformation of light into electricity.
• An object of the present invention is to provide a photovoltaic module in which a situation of stability of voltage and current is determined through a reduction of the harmonics that are generated in each group of LEDs.
• Another object of the invention is to provide a photovoltaic module in which the use of devices for the elimination of harmonics and for achieving a clean electric current can be avoided downstream of the photovoltaic module.
• the twelfth LED of each group of LEDs that is separated from the successive group by means of a device adapted to limit current peaks is a low voltage LED. e.g. having a voltage of 0,8 V, which is not used as an absorber of sunlight, but as a user of the aforementioned periodic components of the current, to consume them and to prevent ⁇ said periodic components to flow in the inverter and then in the electric grid.
• Figure 1 is a schematic front view of a module according to the present invention.
• Figures 2 and 3 are a rear view and a side view, respectively, of the module of Figure 1.
• FIGS. 4 and 5 are enlarged schematic partial cross-section views of the module ⁇ according to the present invention in two variants of diode assembly, and
• Figure 6 is a circuit partial view of a photovoltaic module according to the present invention.
• Figures 1 , 2 and 3 show schematically a front v iew, a( rear v iew and a side view, respectively, of a photovoltaic module 1 for the conversion of sunlight or artificial light into electric power.
• a protection block which is conventionally provided in the solar panels and positioned on the back of the photovoltaic module 1 .
• Output cables 20 for the collection of the power produced exit the protection block.
• the photovoltaic module 1 comprises in front an array of conversion elements ⁇ generically indicated as 3 and better shown in Figures 4 and 5, which are enlarged schematic partial cross-section views of the module according to the present invention in two variants of diode assembly.
• Indicated as 4 in these figures is a peripheral profiled section made of a light alloy, for example aluminium, and as 5 a sheet for rear protection.
• the photovoltaic module 1 is protected with a layer 6 of glass or( transparent plastic material, such as that normally employed in the Held of photov oltaic solar panels with the name of Tedlar*.
• the conversion elements 3 are a plurality of LEDs mounted on a printed circuit board 7 acting for both the electrical connection and the support of the LEDs 3.
• the LEDs 3 are preferably of the type operating in the infrared. These LEDs 3 are not used in their normal function of light ⁇ emitters when they are subjected to a voltage, but as real solar cells. As will be seen later, the LEDs 3 are arranged in series and in parallel to give an output from the photov oltaic module 1 in a voltage and in a current adjusted to the needs of the user. According to the invention, the LEDs 3 are able to operate even in the case of cloudy sky and offer a greater mechanical resistance to wear and better electrical performance ( than LEDs which capture the radiation mainly in the visible.
• a layer 8 of Tedlar* that is preferably white-coloured to facilitate the further irradiation.
• an air chamber 9 which serves inter alia to make and check welds.
• the figures 4 and 5 differ ⁇ from each other only for the different inclination of the LEDs 3 : in Figure 4 the LEDs are oriented with an inclination of about 30° with respect to the perpendicular to the printed circuit board 7 to be directed by itself in direction of the light source. In Figure 5, the LEDs 3 are arranged perpendicularly to the printed circuit board 7. and this requires that the entire module is variously inclined to be directed toward the light ( source.
• the LEDs 3 are represented by their conventional syinbology as if they were used as light emitters.
• the LEDs 3 form rows 10 of any number of semiconductors which are connected together in series, the rows 10 being connected in parallel at their ends with legs 1 1 leading to the output cables 20.
• Circuit ⁇ connections are made previously on the printed circuit board 7. while the LEI) 3 are applied by means of machines, not shown, performing automatic welding.
• the LEDs used are very small, I mm x 1 mm, when they are deprived of the protection housing. By way of example, if they are placed on a module of 2 m x 2 m.
• the LEDs may be ideally in a number of 4 million, if spaces for their connection are disregarded.
• the rows of LED 5 in series are divided into 12 groups being separated from one another by means of a device capable of preventing the attainment of peak currents that might trigger the ignition of LED 3 in following groups 12 in the same row of LEDs in series.
• a device may be a resistor 13.
• the resistors 13 acting as dissipators, can be made also simply by bending the connection wire between a group 12 and the other in the same row 10 of LEDs generally according to an omega-shaped profile.
• the groups 12 are of twelve LED 3 each.
• the voltage of the twelfth LED has a characteristic of voltage low er than that of the other LEDs. For example, the twelfth LED has a voltage of 0.8 V.
• the power obtainable from a photovoltaic module according to the invention would be ideally of 3.2 kW assuming that the LEDs 3 are in a number of 4 million and a conventional solar irradiance is of 1 kW/m 2 . Taking into account the larger size of the LEDs 3 and other necessary gaps, their number can be assumed f approximately 3.6 million in an area of 4 m 2 resulting in a yield of 2.88 kW.
• This high power obtained from a solar photovoltaic module of about 4 m 2 gives a measure of the efficiency of the invention compared to conventional panels thai, at the same conventional irradiation, require an area of approximately 8 m 2 to provide only 1 kW.

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Citations (3)

• 2013
  • 2013-07-04 WO PCT/IT2013/000187 patent/WO2015001579A1/en active Application Filing

Patent Citations (3)

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