DE102008020815A1 - Photovoltaic solar module - Google Patents

Abstract

The invention relates to a photovoltaic solar module, comprising at least one solar cell with an optical radiation concentrator, wherein the module is in communication with a drive unit for controlled, sunlight-dependent tracking. According to the invention, the solar cell of the module has an increased output voltage in the case of standard dimensions of industrially manufactured silicon cells, the radiation converter being designed in such a way that, with an arrangement of solar cell and radiation converter on essentially opposite sides of the module, the light spot obtained enables concentrated illumination up to the solar cell edge.

Description

The The invention relates to a photovoltaic solar module comprising at least a solar cell with an optical radiation concentrator, wherein the module with a drive unit for controlled, sunlight-dependent Tracking is related, according to the preamble of claim 1

From the DE 198 04 469 A1 is a photovoltaic solar module previously known, which has directly juxtaposed cells, which are protected by a transparent disc against environmental influences. The solar module described therein consists of an arrangement of individual square cells with associated mirrors. The integrated mirror cell structure requires solar radiation perpendicular to the module surface. For this reason, a mechanical sun tracking is available.

In the concentrator photovoltaic device with positioning aid to DE 10 2006 002 465 A1 It is also about the direct conversion of solar energy into electrical energy. The device comprises a housing which is provided with at least one light entry plate formed of a light-transmissive material. Furthermore, a plurality of solar cells is present, which are each located at a distance from the at least one light entry plate on the side facing away from the sun inside the housing. The light entry plate is provided with an optical unit for concentrating or bundling the solar radiation entering through the light entrance surface onto the smaller areas of the solar cells, wherein the housing for forming the side walls is made as an injection molded part.

At the thermal solar collector after DE 202 10 881 U1 is within a transparent, spherical shell, a tubular, flowed through by the heat transfer channel exists, wherein a concave mirror is used to amplify and concentrate the solar radiation. The tubular heat-receiving channel through which the heat transfer medium flows is approximately formed into a compact sphere and is located in the center of the transparent, spherical envelope.

The solar collector for the concentration of sunlight on a solar cell after DE 10 2006 000 682 A1 uses semiconductor photoelements with p- and n-type regions using the internal photoeffect. The local solar collector has at least one carrier body of light-conducting polymethacrylate plastic material with a transparent, facing the sunlight top and with particular laterally applied cut edges of the wall of the carrier body or such cut edge sections and arranged there solar cells. The cut edges are transparent to the sunlight sunk into the substrate and redirected there. The support body itself is designed as a shell-shaped, spherical shell, wherein at least one omission for forming the cut edges of the solar cells is arranged in order to form cut edge sections for arranging the solar cells in the shell-shaped shell. The remaining cut surface is provided with a reflection coating. Furthermore, on the outside of the coating on the shell-shaped carrier body, a further coating is applied, which reflects the infrared portion of the incident sunlight and is transparent to the visible portion of the incident sunlight, so that the efficiency of the overall arrangement of an improvement based on the hitherto known state of the Technology subject.

by virtue of the silicon shortage and the high proportion of costs for the semiconductors at the total cost of a standard Photovoltaic module is the concentration of sunlight on one smaller area of the relatively expensive semiconductor material an important method to reduce the investment costs for photovoltaic systems and subsequently the electricity production costs from solar energy continue to reduce.

Previous Efforts in this direction are on extreme concentration factors from 500 and more also and especially to the high cost for the III-V commonly used here Multijunction solar cells based on compound semiconductors to compensate.

The Chip sizes of such concentrator modules are in the range of a few square millimeters. To the resulting heat remove from these chips are consuming heat spreading and apply cooling techniques. Furthermore Such concentrator modules must by highest precise biaxial mechanical tracking systems be moved, because the focal spot of the concentrator lenses used just about as big as the solar cell chips. Also The slightest deviations from the optimal position of the sun can therefore be avoided Walk down the light spot from the solar cell chip.

Biaxial tracking devices, so-called movers, will also use standard modules in many square meter arrangements except for the concentrator solar modules described above det. The tracking by a corresponding motor drive, however, allows only a more or less continuous irradiation with sunlight at an angle of incidence of substantially 90 °. However, the precision requirements related to such tracking are much lower, since smaller angular deviations from the exact position of the sun lead to no significant loss of performance of the solar cell modules, but the moving masses are very large, so that stable foundations and correspondingly expensive supporting structures are required.

One Another disadvantage is the very large area of Modular pallets with the resulting extreme wind load.

Out The above, it is therefore an object of the invention, an evolved Photovoltaic solar module comprising at least one solar cell specify with an optical radiation concentrator, wherein the Module with a drive unit for controlled, sunlight-dependent Tracking communicates. In the to be created Solar module should the production costs with increased efficiency be reduced so that open up new applications.

The Solution of the object of the invention is achieved by a solar module according to the combination of features according to claim 1, wherein the dependent claims at least expedient Represent refinements and developments.

Therefore The basic idea of the invention is that the for the advanced solar module used solar cell standard dimensions industrially and thus inexpensively manufactured silicon cells with having increased output voltage, wherein the radiation concentrator is designed in particular in the form of a lens that at a Arrangement of solar cell and radiation concentrator at substantially opposite Pages of the module or module housing the resulting light spot a concentrated lighting allows up to the solar cell edge.

The used silicon solar cells should have a diameter or a quasi-diagonal extent in the range between 100 mm and 300 mm, depending on standard wafers, such as they are commonly used in monocrystalline cells Find.

at the photovoltaic solar module becomes the captured sunlight preferably with a Fresnel lens so on a solar cell with standard dimensions focussed that this is completely covered with more than one sun is illuminated. Typical orders of magnitude are here a 5 to 10 times the solar concentration, so not the Thermal problems occur, as with concentrator modules given with highly efficient III-V compound semiconductor diodes are.

at A preferred embodiment of the invention are concentrators and solar cell on a common axis, opposite each other and arranged concentrically.

Of the Concentrator is, as already explained, as plano-convex lens, planar Fresnel lens or as a spherical Fresnel lens formable.

The Focal length of the lens is preferably chosen so that at predetermined distance between lens and solar cell diameter the lens spot at this distance position equal or insignificant greater than the cell diameter.

The Solar cell of the solar module according to the invention connected at the back with a cooling plate, at the same time serves to stabilize the cell.

The Area dimensions of the cooling plate correspond essentially that of the lens used.

at a circular lens substantially corresponds to the lens diameter the diameter of the likewise circular cooling plate part.

The Module housing can in a particularly preferred embodiment the invention have the shape of a sphere, wherein within the Ball the solar cell and the radiation converter are arranged.

But the module housing can also ausgestaltend have the shape of a hollow cylinder, wherein in be arranged within the hollow cylinder, the solar cell and the radiation concentrator.

at a spherical Fresnel lens as a radiation concentrator the lens can be preferably embedded in the ball jacket and so that virtually be part of the ball itself.

The Solar cell with cooling plate is preferably along a Ball cap separating section inserted into the ball jacket and closes the resulting opening from.

Also there is the possibility of using a planar lens this along a part separating a spherical cap in the Insert ball jacket in one place, parallel to the position of the solar cell is opposite.

Of the Distance between radiation concentrator and solar cell is about equal to the diameter of the concentrator.

The ball diameter in turn is at least a factor of √ 2 chosen larger than the diameter of the radiation concentrator.

Of the Distance between radiation concentrator and solar cell inside of the hollow cylinder is equal to or smaller than the diameter of the used in this case radiation concentrator.

Of the Radiation concentrator can be in a module housing in shape a hollow cylinder, the bottom surface and the solar cell form the top surface of the hollow cylinder, wherein the longitudinal axis the hollow cylinder directed to the radiation source tracked becomes.

The Module housing is to simplify the manufacturing technology and in the interest of uncomplicated handling z. B. from two Hemispheres or two half-shell-shaped bodies and can be assembled accordingly.

at An embodiment of the invention can be a plurality of individual modules on or in a common flat carrier are arranged, the carrier then over a single tracking drive unit has.

The Invention will be described below with reference to embodiments and explained in more detail with the aid of figures become.

in this connection demonstrate:

1 a schematic representation of a large-area silicon solar cell, in the radiation incident direction of a plano-convex lens is arranged upstream;

2 a schematic representation of the radiation profile of a Mehrsonnenbestrahlung a large-area silicon solar cell, wherein a Fresnel lens is used as a radiation concentrator;

3 an embodiment of the solar module housing as a ball with inserted planar Fresnel lens and inserted solar cell having a cooling plate;

4 an embodiment of the solar module with likewise spherical housing, wherein a part of the spherical shell is replaced by the spherical Fresnel lens used as a radiation concentrator;

5 a further embodiment of the module housing, designed as a hollow cylinder with planar Fresnel lens and silicon solar cell;

6a , b exemplary basic structures of a solar cell with increased output voltage in square or quasi-quadratic as well as in circular or circular shape;

7A an exemplary embodiment of a roof-integrated system with spherical module housing;

7B a representation similar to that after 7A with symbolized sun tracking;

7C a plan view of a basic embodiment of a roof integrated system of many spherical modules with Fresnel lenses and silicon solar cells;

8A an exemplary embodiment of an outdoor system in terrace form with hollow ball module housings according to the invention;

8B an exemplary embodiment of an outdoor installation in terrace form, z. B. on mountainsides, with hollow cylinder modules according to the invention;

9 an exemplary representation of a maximum morning angle α at a distance d, wherein with larger d and α may be greater and the same applies to the evening angle β = α, and

10 a representation of an embodiment of the invention, wherein a plurality of individual modules is arranged on or in a common planar support.

According to embodiment It is assumed that a standard solar cell when irradiated with several, so n = 2, 3 ... 10 suns, an n-fold electric Can produce power.

If per watt of installed power only the fraction 1 / n of silicon material is needed, the system costs and the Energy production costs are reduced.

combined Sun tracking can also be per installed power Up to 30% more energy is generated.

In the solution according to the embodiment, the solar cell is located 2 in the focal region of a lens that has the focal length f = x + y of either a biconvex or plano-convex lens 1 ( 1 ) or a Fresnel lens 4 ( 2 ) at a distance y before the focal point.

There the illumination spot is circular, it is advantageous also to carry out the solar cell circular. This means, an otherwise occurring squaring of the ingots before wafer production can be omitted. This saves on the one hand an expensive operation and in addition, a 4 / π higher power per Fresnel lens produced as in quasi-square cells.

In an embodiment in which an illuminance of n suns is desired, the diameter of the lens D _{Fresnel is} initially roughly around √ n larger than the diameter of the solar cell D _cell = 2 B , Conveniently, then this stretching factor on the light spot designed by 10% larger 3 on the solar cell surface, ie on the diameter 2a about the same 2 . 2 B instead of being exact 2 B applied. This results D Fresnel = 2a√ n = 2, 2b√ n In order to ensure the concentrated illumination to the edge of the solar cell even with a small inclination setting, ie with low inaccuracy of the sun tracking.

erhöht.If the intensity loss is also to be compensated by the extinction α (about 0.1) of the Fresnel lens, the area of the lens is additionally increased by the factor 1 / (1-α), ie the diameter D _{Fresnel is} increased by the factor

elevated.

hinter der Linse auf einer wärmespreizenden Kühlplatte mit gleichem Durchmesser wie dem der Fresnel-Linse D_Fresnel = x angebracht.An inventive embodiment of the tracked concentrator module is that each solar cell is assigned its own lens and its own tracking device. The solar cell is spaced x = D _Fresnel =

behind the lens on a heat-dissipating cooling plate with the same diameter as that of the Fresnel lens D _Fresnel = x attached.

In a first embodiment, the module according to the invention is designed as a hollow plastic ball, which in the front region a plane Fresnel lens ( 3 ) or a spherical Fresnel lens ( 4 ) with diameter D _Fresnel for n-fold focusing on the individual solar cell in the rear part of the module housing.

gekoppelt.In this case, the focal length f = x + y of the Fresnel lens over the diameter of the hollow sphere is fixed to the lens diameter x = D _Fresnel =

coupled.

After the set of rays applies with reference to 3 following:

The means: all geometry data of the tracked concentrator module can be derived from the diameter of the cell.

For a round cell with 2 B = 205 mm diameter is therefore valid: D bright spot = 2a = 2, 2b = 1.1 × 205 mm = 22.55 cm

For n = 10 and α = 0.9 follows: x = D fresnel = 22.55 cm · √ 10 / (0.9) = 22.55 cm × 10/3 = 225.5 / 3 cm = 75.2 cm => y = x / [10/3 - 1] = 75.17 cm / 2.33333 = 32.21 cm => f = x + y = 75.17 cm + 32.21 cm = 107.4 cm and D Bullet = √ 2 X = 106.3 cm

So for a concentration of 10 suns, the focal length of the lens is down to 1% equal to the diameter of the sphere and √ 2 times the diameter of the light spot (= 1.1 · D _cell ).

In a further embodiment of the invention, the radiation concentrator is in the form of a Fresnel lens and the cooling plate 6 in a plastic hollow cylinder 12 ; 13 ( 5 ) used. This plastic hollow cylinder can work in the same way as the ball 9 biaxial, ie be tracked in azimuth and elevation. In this case, the focal length of the Fresnel lens 5 be set shorter regardless of their diameter, so that there is a minimization of the linear expansion of the hollow cylinder.

Of the Module body for the aforementioned embodiments can be advantageous by addition of hemispheres or half shells be assembled to both in the production and at to gain advantages in transport.

Due to the n-times higher light radiation, an n-fold higher current per square centimeter surface is generated in the solar cell. If, according to the invention, solar cells with an increased output voltage are used (schematic illustration according to FIG 6a and b), the clamping voltage is increased by the internal monolithic series circuit of portions of the solar cells and reduced the current to the same extent. If n-diodes are also advantageously provided at an n-fold light concentration, the current intensity remains in the previously used and controlled order of magnitude while the open clamping voltage rises to n * V _OC . In typical cell designs with V _OC = 0.6 V and n = 10, this would be about 6 V. It follows that a cell that provides 5 W for a sun delivers 50 W of energy when irradiated with 10 suns without the Current is much higher than comparable standard cells usual low output voltage.

The module construction according to the invention combines a housing for the solar cells, the Konzent rator, ie a lens and spacer receives. The module can also partially integrated into the housing, have the drive unit and the necessary mechanism for controlled, sunlight-dependent tracking.

As from the representations in particular after the 7A and 7B can be seen, the spherical variant of the presented module can also be on small flat roofs or built into sloping roofs (the latter is in the 7A and B, the execution related to a flat roof with the 7C shown).

Likewise, the variants presented with spherical or cylindrical module or module housing can also be advantageously placed in outdoor facilities and long rows including on hill or mountain slopes (see 8A and 8B ). The lateral distance depends here on the desired maximum angular position in the direction east and west ( 9 ). That is, the later in the morning with the sun tracking is started (morning angle α) and the sooner it is to end in the evening (evening angle β), the closer the modules may move together without shading each other.

The Signal for the position of the radiation source to be applied, d. H. the sun, can be made from a single simple processor module to all tracking devices of the system at the same time be forgiven, thereby reducing the cost of the position calculation and reduce signal output.

The Weight of the individual modules can be kept very low. There the modules especially in the spherical and hollow cylindrical shape in the center of gravity are hung for the necessary Nachführungs- and adjustment movements required forces and moments extremely small. This can be the necessary Motorization will be easier and cheaper.

In a supplementary embodiment, the inventive principle of the illumination of individual large silicon cells with n-times concentrated light can also in a common module carrier box with many Fresnel lenses 102 on the sun-facing surface and correspondingly many silicon solar cells 103 on the floor of the carrier mounted on a biaxial tracking device (see 10 ). The height 101 of the carrier box 100 is then as large as the optimized length of the cylinder according to the invention according to the corresponding embodiment of the single module with the same size lens and the same size solar cell.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 19804469 A1 [0002]
• - DE 102006002465 A1 [0003]
• DE 20210881 U1 [0004]
• - DE 102006000682 A1 [0005]

Claims (22)

Photovoltaic solar module, comprising at least one solar cell with an optical radiation concentrator, wherein the module is connected to a drive unit for controlled, sunlight-dependent tracking, characterized in that the solar cell has a higher output voltage for standard dimensions of industrially manufactured silicon cells, wherein the radiation concentrator is designed so in the case of an arrangement of the solar cell and the radiation converter on essentially opposite sides of the module, the light spot obtained enables concentrated illumination as far as the solar cell edge. Module according to claim 1, characterized in that the concentrator and the solar cell on a common axis, are arranged opposite each other and concentric. Module according to claim 1 or 2, characterized that the concentrator as a plano-convex lens, a planar Fresnel lens or formed as a spherical Fresnel lens. Module according to claim 3, characterized in that the focal length of the lens is chosen so that at a given Distance between lens and solar cell the diameter of the light spot equal or insignificantly larger at this distance position as the cell diameter is. Module according to one of the preceding claims, characterized in that the radiation concentration factor the arrangement is between 2 and 20, preferably between 4 and 10. Module according to one of the preceding claims, characterized in that the solar cell is a backside Has cooling plate. Module according to claim 3 or 4 and 6, characterized that the area dimensions of the cooling plate in Substantially correspond to those of the lens used. Module according to claim 7, characterized in that for a circular lens, the lens diameter is the diameter the likewise circular cooling plate corresponds. Model according to one of the preceding claims, characterized in that the module housing the shape having a ball, wherein within the ball, the solar cell and the radiation converter are arranged. Module according to one of claims 1 to 8, characterized in that the module housing is in the form of a Hollow cylinder, wherein within the hollow cylinder, the solar cell and the radiation converter are arranged. Module according to claim 9, characterized in that in a spherical Fresnel lens as a radiation concentrator the lens is embedded in the bullet and a component the ball or the ball sheath forms. Module according to claim 9 or 11, characterized that the solar cell with cooling plate along a a ball cap separating section is inserted into the ball jacket. Module according to claim 9, 11 or 12, characterized that the planar lens along a separating a ball cap Section is inserted into the ball jacket at a location that the position of the solar cell is parallel opposite. Module according to one of the preceding claims, characterized in that the distance between the radiation concentrator and solar cell is about equal to the diameter of the concentrator. Module according to claim 9, characterized in that the ball diameter at least larger by a factor than the diameter of the radiation concentrator. Module according to claim 10, characterized in that that the distance between radiation concentrator and solar cell within the hollow cylinder equal to or smaller than the diameter of the radiation concentrator. Module according to Claim 16, characterized that the radiation concentrator the floor surface and the Solar cell form the top surface of the hollow cylinder, wherein directed the longitudinal axis of the hollow cylinder to the radiation source is tracked. Module according to one of the preceding claims, characterized in that the module housing of two hemispherical or half-shell-shaped bodies composable is. Module according to one of the preceding claims, characterized in that the solar cell is a square or has quasi-square surface shape. Module according to one of claims 1 to 18, characterized in that the solar cell is a circular or circular Has surface shape. Module according to one of the preceding claims, characterized in that a plurality of individual modules or in a common planar carrier or Carrier box is arranged, wherein the carrier or carrier box the tracking drive unit or communicates with such a unit. Module according to one of the preceding claims, characterized in that the output voltage by a factor between 2 and the concentration factor of the radiation concentrator is increased.