DE102009020446A1 - Photo voltaic system for converting radiation energy of sun light into electrical energy, has solar altitude dependent processing parameter determined in controlling device, and changeable frame angle produced from angle difference - Google Patents

Abstract

The system (01) has a frame (03) that is rotary driven around a vertical rotation axis by a drive device for positioning the frame at a changeable frame angle relative to a determined direction. A solar altitude dependent processing parameter is determined or induced in a controlling device, and a differential angle is measured from the solar altitude dependent processing parameter. The changeable frame angle is produced from the angle difference between an actual azimith angle of sun beams (11) and the differential angle. An independent claim is also included for a method for operating a photo voltaic system for converting sun light into electrical energy.

Description

The The invention relates to a photovoltaic system for converting sunlight in electrical energy according to the preamble of claim 1. Next The invention relates to a method for operating such a photovoltaic system.

Generic photovoltaic systems serve to convert sunlight into electrical energy. The actual transformation of the radiation energy contained in sunlight in electrical energy takes place in photovoltaic modules, on where the resulting electrical power removed as DC can be. To the effectiveness of Increase power generation, are generic photovoltaic systems equipped with an adjustable frame on which the photovoltaic modules are mounted. The frame can be about a vertical axis rotate to follow the relative position of the sun uniaxially. The positioning of the frame is done by setting a frame angle relative to a particular cardinal direction, so that the frame thus thus relative to the azimuth of the sun, d. H. the oriented to one direction horizontal angle the sun, can be aligned.

The generic photovoltaic systems are Furthermore Characterized in that the photovoltaic modules tilted twice are. The first inclination refers to the inclination of the frame plane, on which the photovoltaic modules are mounted in total. This designated as frame height angle Inclination angle of the frame level indicates the inclination angle of Frame plane relative to a horizontal plane. In addition to This tilt of the frame level are then still the photovoltaic modules even with a module height angle mounted inclined on the frame level. By this double inclination the photovoltaic modules with the frame height angle on the one hand and the module height angle On the other hand, an orientation of the surface of the photovoltaic modules relative to the average solar altitude (elevation) of the sun be reached at the respective location, since the photovoltaic modules in the generic photovoltaic systems across from the height the sun are not adjustable. Because the necessary angle of inclination of the photovoltaic modules is the addition of frame height angle and module height angle results, can the generic photovoltaic systems be made flatter accordingly, since the inclination of the photovoltaic modules not only by the frame height angle must be realized.

at the known photovoltaic systems, the frame angle, with the the frame is aligned relative to the azimuth of the sun, usually so calculated that the photovoltaic modules with their surface approximately perpendicular aligned to the azimuth of the sun. Due to this vertical orientation the projected into the horizontal plane surface of the photovoltaic modules becomes the relatively highest yield realized at radiation energy. To the movement of the sun over the To be able to follow the day be the racks of the known photovoltaic systems by suitable Controlled nachgesteuert or nachge regulated to the photovoltaic modules align with the current solar azimuth.

exact Investigations of the effectiveness generic photovoltaic systems have shown that the respective exact alignment of the photovoltaic modules in the direction of the azimuth of the sun not in all operating conditions one optimum yield of radiant energy contained in solar radiation results. Cause for this are for example temperature effects. Because of rising temperature the photovoltaic modules decreases the efficiency of the current efficiency from. Also, the partial shading of individual photovoltaic modules or the only incomplete Reflection of sunlight on individual photovoltaic modules one negative influence on the current efficiency of the photovoltaic system to have.

outgoing From this prior art, it is therefore an object of the present Invention to propose a new photovoltaic system with which the Problems described above with regard to the yield of electrical Energy can be positively influenced. It's up to you to continue of the present invention, a method of operating such To propose photovoltaic system.

The Photovoltaic system according to the invention is based on the basic consideration, that determines at least one sun-dependent process parameter or derived from other parameters. Depending on these sun-dependent process parameters will be touching calculated a difference angle. This difference angle is there at which angle difference the frame angle with which the frame positioned relative to the sun, between the current azimuth the sun and the frame angle of the frame is present. This In other words, that means through the calculation and adjustment the differential angle positioning of the frame relative to Azimuth of the sun, which either runs after the azimuth of the sun or leads. By adjusting or advancing the frame relative to The position of the sun can then have a positive effect on the sun-state-dependent process parameter be achieved.

Which sun-dependent process parameter is the basis for the calculation of the differential angle is basically arbitrary. After a In the first preferred embodiment, the shadow cast of the photovoltaic modules is calculated or derived as a sun-state-dependent process parameter. Because of the inclination of the photovoltaic modules with the module height angle on the frame level is caused by the individual photovoltaic modules a shadow on the underlying surfaces. If a further photovoltaic module is located on one of the surfaces behind it, then a partial shadow on the photovoltaic modules lying behind can be caused by this shadow cast. Such partial shading, however, has an extraordinarily negative influence on the current efficiency in the case of photovoltaic modules. Because due to the special circuit of each photovoltaic wafer in the photovoltaic modules, it follows that the electrical power is determined in each case by the photovoltaic wafer, which emits the currently lowest electrical power. If a photovoltaic module is partially shaded, even if it is only on a very small area, this can significantly reduce the electrical output of the photovoltaic module as a whole. If, for example, the photovoltaic module is partially shaded to only 10% of its area, this can result in an 80% reduction in the electrical power achieved. Such unwanted shading effects can be prevented by the inventive lagging or leading the frame of the photovoltaic system relative to Sonnenazimut. Because an exact analysis of the radiation conditions shows that the relative angle of incidence of the solar radiation does not necessarily have to be influenced by an adjustment of the module height angle or of the frame height angle. Rather, a desired influencing of the angle of incidence can be realized from above by the inventive lagging or leading the frame with the derived differential angle from the shadow. This means in other words that by rotating the frame about the axis of rotation of the frame, which extends vertically, influencing the relative angle of elevation of the solar radiation relative to the photovoltaic modules is possible.

by virtue of the inclined arrangement of the photovoltaic modules with the module height angle relative to the frame level, it turns out that between the individual one above the other arranged photovoltaic modules remains a gap. to Increase the Current efficiency can in this space preferred additional reflection elements be attached. By these reflection elements can then additional Sunlight as reflection on the photovoltaic system provided photovoltaic modules are thrown.

So far at the photovoltaic system additional Reflective elements for reflecting sunlight onto the photovoltaic modules are provided, and the generated by the reflection elements Reflection throw, d. H. so in addition to the photovoltaic modules reflected sunlight, as a sun-dependent process parameter for the calculation taken into account the difference angle become. Because by appropriate adjustment of the differential angle and the consequent lag or anticipation of the frame across from In the solar azimuth, the intensity of solar radiation can be varied become. This is particularly advantageous when the temperature in the photovoltaic modules over an undesirable Measure increases. By leading or lagging the frame relative to the Solar azimuth can increase the intensity the solar radiation then withdrawn become. Furthermore can be achieved by adjusting the frame angle be that the reflection throw on the photovoltaic modules enlarged accordingly or reduced. By enlarging or Reducing the reflection throw states can be avoided in which only partial surfaces of the Photovoltaic modules are illuminated by the reflection. Because only by a substantially complete certificate of photovoltaic modules with the reflection light is achieved by the reflection of sunlight the electric power of the solar modules is increased. Covered the Reflection throw, however, only a partial area of the photovoltaic module, the electrical yield of the photovoltaic module increases substantially not at, but at the same time the temperature of the photovoltaic modules increased by the reflection light in an undesirable manner.

in the Regard to the desired Influencing the energy yield by the leading or lagging Setting the frame relative to Sonnenazimut it is special advantageous if the on the frame level at a height next to each other arranged photovoltaic modules are electrically connected in series. This will ensure that the photovoltaic modules in a height of the rack level a series connection and insofar as regards the sun-dependent process parameter, for example, the shadow cast, for all these mounted at a height Photovoltaic modules rule the same conditions. Will be so by leading or lagging the frame relative to the solar azimuth Partial shading of the photovoltaic modules in a particular height of Frame level set, so apply to all at the same height of the frame level mounted photovoltaic modules the same Einstrahlparameter, so that from the series connection of these photovoltaic modules of the correspondingly positive effect overall.

The geometric conditions on the photovoltaic system according to the invention are basically arbitrary. According to a preferred Ausfüh The frame plane should be inclined with a frame height angle in the range of 6 ° to 10 °, in particular with a frame height angle of approximately 8 °.

The Photovoltaic modules in turn should be preferred at the rack level with a module height angle from 25 ° to 35 °, in particular with a module height angle of 32 °, be inclined.

By the lagging or Advance of the frame relative to the solar azimuth through the compliance of the invention of a differential angle, the energy output by the something deteriorated sun angle partially deteriorated. To this actually unwanted To mitigate effect, the frame plane relative to the horizontal plane in addition in their direction of rotation around a second height adjustment angle be inclined.

The inventive method is characterized by the fact that after the determination or derivation at least one sun-dependent process parameter, for example, the current shadow cast or the current reflection throw, due this sun-dependent Process parameters a differential angle is calculated. After the calculation the difference angle then becomes the frame with this difference angle set relative to the current solar azimuth, leaving the frame as a result of the solar azimuth lags or leads ahead.

According to one first method variant, the current shadow is determined, to derive the difference angle for to calculate the lead or the lag of the frame.

alternative or additively, the current reflection throw can also be calculated become.

So far the current shadow for the calculation of the difference angle should be considered the calculation of the differential angle done in a way that Partial shading of the successively arranged photovoltaic modules be avoided. In particular, it is particularly advantageous if caused by a more advanced photovoltaic module Shadow grade so falls on the underlying surface that the outer border the shadow cast at the lower end of the photovoltaic module behind it lies.

at consideration of the current reflection throw should calculate the difference angle just always done so that the reflection throw behind it lying photovoltaic module either completely or not at all. Because one Partial certificate of the photovoltaic module with reflected sunlight is of very little use in terms of current efficiency, whereas the negative influences are still present due to rising temperatures.

Various Aspects of the invention are shown schematically in the drawings and are explained below by way of example.

It demonstrate:

1 a first embodiment of a photovoltaic system according to the invention in a side view;

2 the photovoltaic system according to 1 in top view;

3 the photovoltaic system according to 1 in front view;

4 a section of the photovoltaic system according to 1 in lateral view;

5 the clipping according to 4 in top view;

6 the clipping according to 5 after setting a differential angle;

7 the clipping according to 6 after setting the difference angle in lateral view;

8th a second embodiment of a photovoltaic system according to the invention in a side view;

9 the photovoltaic system according to 8th in top view;

10 a section of the photovoltaic system according to 8th in lateral view;

11 the clipping according to 10 when setting a first differential angle in lateral view;

12 the clipping according to 10 when setting a second differential angle in lateral view.

1 . 2 and 3 show a photovoltaic system 01 with one around an axis of rotation 02 rotatable frame 03 and a plurality of photovoltaic modules mounted on the rack 04 , The photovoltaic modules are in 5 rows of 13 photovoltaic modules 04 arranged in parallel one above the other, with the photovoltaic modules 04 in every row 05 are connected in series.

The photovoltaic modules 04 are on a rack level 06 arranged, with the frame level 06 with a frame height angle 07 opposite to a horizontal plane 08 is inclined. The individual photovoltaic modules 04 in turn are on the rack level 06 again with a module height angle 09 arranged inclined. Is the frame height angle 07 for example 8 ° and the module height angle 09 For example, 32 °, so there is a tendency of the photovoltaic modules 04 in total, compared to the horizontal plane 08 of 40 °. But because the frame level 06 itself is not inclined with the inclination angle of 40 °, but only the frame height angle 07 of 8 °, is the height of the photovoltaic system 01 relatively low.

How out 3 can be seen, is the frame level 06 also with a second frame height angle 10 inclined with respect to a second reference plane.

In 1 and 2 is schematic of the sunlight 11 indicated. To indicate the current solar radiation 11 relative to the arrangement of the photovoltaic modules 04 serves the elevation angle 12 which indicates the angle of solar radiation relative to the horizon. This elevation angle 12 is also specified or designated as height, elevation or altitude. Next, the geometry of the sunlight results from the in 2 indicated azimuth angle 13 , the horizontal angle of the sun's rays 11 relative to a particular compass, for example, the south direction 14 , indicates.

4 schematically shows a section of the photovoltaic system 01 with the frame level 06 and two photovoltaic modules 04 when the frame is aligned 03 in the direction of the current solar azimuth. This current solar azimuth results in an elevation angle 12a for the sunbeams 11a , Because the elevation angle 12a in the example shown is very flat, throws the front photovoltaic module 04a a partial shade 24 on the underlying photovoltaic module 04b , This partial shade 24 is the back end of the in 4 indicated shadow cast 14 The front photovoltaic module 04a on the underlying surface throws.

5 shows the two photovoltaic modules 04a and 04b and emerging from the sun's rays 11a resulting shadow 14a with partial shading 24 on the rear photovoltaic module 04b , The central axis 15a the photovoltaic modules 04a and 04b runs parallel to the solar azimuth and thus parallel to the sun's rays 11a , The partial shade 24 on the rear photovoltaic module 04b is in terms of the yield of electrical energy to the photovoltaic module 04b and at all the same height arranged photovoltaic modules extremely negative, because due to the special circuit of the photovoltaic modules 04b the on a photovoltaic module 04b the amount of electrical power consumed always depends on the area of the photovoltaic module that is irradiated with the weakest solar intensity.

To avoid the negative influence of the partial shade 24 can according to the invention the frame 03 with a difference angle 16 be positioned in a lagging or anticipatory manner. By this lagging or

Advance of the central axis 15b opposite to the solar azimuth is achieved that the geometry of the shadow cast 14 in the in 6 changed way. The length of the shadow cast 14b remains unchanged. Due to the changed irradiation direction of the sun's rays 11a relative to the rotated center axis 15b the photovoltaic modules 04a and 04b is achieved, however, that shortens the shadow in the corresponding section plane and thus a partial shading of the rear photovoltaic module 04b is avoided. As a result, by adjusting the difference angle accordingly 16 be achieved relative to the solar azimuth that the outer boundary 17 the shadow cast 14b from the front photovoltaic module 04a is caused, always at the bottom 18 behind the lying photovoltaic module 04b lies.

7 shows the clipping according to 6 in a side view along a sectional plane through the central axis 15 the photovoltaic modules 04 , It can be seen that in this projection plane the light beam 11 straight to the lower end 18 of the photovoltaic module 04b falls, so that a partial shading does not occur. In the corresponding section plane, therefore, there is another, apparent elevation angle 19 the sunbeams 11a , which is steeper than the elevation angle 12 without setting the differential angle 16 is.

8th and 9 show a second embodiment of a photovoltaic system 20 , their basic structure on the photovoltaic system 01 based. In addition, at the photovoltaic system 20 between the rows 05 of photovoltaic modules 04 still each reflection elements 21 arranged, with which sunlight as reflection throw on the photovoltaic modules 04 can be reflected.

In 10 is schematized the reflection throw 22 on a photovoltaic module 04 indicated. The reflection throw 22 and its areal limit result from the angle of incidence of the sun's rays 11b and the angle of inclination 23 the reflection elements 21 , In the 10 indicated situation of a partial overlap of the photo voltaikmoduls 04 with the reflection throw 22 is undesirable, because thereby the electrical power of the photovoltaic module 04 is not significantly increased, but an undesirable increase in temperature by the sunlight of the reflected light is unavoidable.

To avoid this undesirable effect can turn a differential angle 16 calculated and thus the elevation angle of the sun's rays 11b in the corresponding sectional plane parallel to the central axis 15 to be changed.

11 and 12 show the situation when setting different differential angles. At the in 11 shown situation by setting a certain differential angle complete coverage of the photovoltaic module 04 with the reflection throw 22a reached.

12 on the other hand shows the situation when setting a different differential angle of the frame 03 , resulting in a total reflection of sunlight 11b without reflection 22 on the photovoltaic module 04 can be achieved. The change in the elevation angle of the sun's rays 11b in each case only by rotation of the frame 03 around the axis of rotation 02 realized. An adjustment of the inclination of the reflection elements 21 or the photovoltaic modules 04 or the frame level 06 is not necessary.

Claims (15)

Photovoltaic system ( 01 . 20 ) for converting sunlight into electrical energy, wherein the photovoltaic system ( 01 . 20 ) a frame ( 03 ), on which several photovoltaic modules ( 04 ) on a rack level ( 06 ), and wherein the frame level ( 06 ) relative to a horizontal plane ( 08 ) with a frame height angle ( 07 ) and wherein the photovoltaic modules ( 04 ) at the rack level ( 06 ) with a module height angle ( 09 ) are mounted inclined, and wherein the frame ( 03 ) with a drive device rotatory about a vertical axis of rotation ( 02 ) is drivable to the frame ( 03 ) with a changeable frame angle relative to a specific cardinal direction ( 14 ), characterized in that in a control device of the photovoltaic system ( 01 . 20 ) at least one sun-state-dependent process parameter can be determined or derived, with a difference angle (from the sun-state-dependent process parameter ( 16 ), and wherein the frame is positioned at a frame angle resulting from the angular difference between the current azimuth angle ( 13 ) of the sun's rays ( 11 ) and the difference angle ( 16 ). Photovoltaic system according to claim 1, characterized in that in the control device of the photovoltaic system ( 01 . 20 ) the current shadow ( 14 ), the at least one photovoltaic module ( 04 ) due to its inclination with the module height angle ( 09 ) is caused on the surface lying behind in the direction of irradiation, can be determined or derived as a sun-state-dependent process parameter, the calculation of the actual difference angle ( 16 ) depending on the current shadow ( 14 ) he follows. Photovoltaic system according to claim 1 or 2, characterized in that on the frame ( 03 ) of the photovoltaic system ( 20 ) at least one reflection element ( 21 ) is attached with at least one reflector surface, wherein with the reflection element ( 21 ) additional sunlight as a reflection ( 22 ) to at least one photovoltaic module ( 04 ) can be reflected. Photovoltaic system according to claim 3, characterized in that in the control device of the photovoltaic system ( 20 ) the current reflection ( 22 ) is determinable or derivable as a sun-state-dependent process parameter, the calculation of the actual difference angle ( 16 ) depending on the current reflection ( 22 ) he follows. Photovoltaic system according to one of claims 1 to 4, characterized in that several on the rack level ( 06 ) at a height next to each other in a row ( 05 ) arranged photovoltaic modules ( 04 ) are electrically connected in series. Photovoltaic system according to one of claims 1 to 5, characterized in that the frame plane ( 06 ) with a frame height angle ( 07 ) from 6 ° to 10 °, in particular with a frame height angle ( 07 ) of 8 °, is inclined. Photovoltaic system according to one of claims 1 to 6, characterized in that the photovoltaic modules ( 04 ) at the rack level ( 06 ) with a module height angle ( 09 ) from 25 ° to 35 °, in particular with a module height angle ( 09 ) of 32 °, are inclined. Photovoltaic system according to one of claims 1 to 7, characterized in that the frame plane ( 06 ) relative to a horizontal plane ( 08 ) in the direction of rotation additionally by a second frame height angle ( 10 ) is inclined. Method for operating a photovoltaic system ( 01 . 20 ) for converting sunlight into electrical energy, wherein the photovoltaic system ( 01 . 20 ) a frame ( 03 ), on which several photovoltaic modules ( 04 ) on a rack level ( 06 ), and wherein the frame level ( 06 ) relative to a horizontal plane ( 08 ) with a rack height angle ( 07 ) and wherein the photovoltaic modules ( 04 ) at the rack level ( 06 ) with a module height angle ( 09 ) are mounted inclined, and wherein the frame ( 03 ) with a drive device rotatory about a vertical axis of rotation ( 02 ) is drivable to the frame ( 03 ) with a changeable frame angle relative to a specific cardinal direction ( 14 ), with the following method steps: a) determination or derivation of at least one sun-state-dependent process parameter, b) calculation of a current differential angle ( 16 ) as a function of the current position-dependent process parameter, c) activation of the drive device for positioning the frame ( 03 ) to a current frame angle resulting from the angular difference between the current azimuth angle ( 13 ) of the sun's rays ( 11 ) and the difference angle ( 16 ). A method according to claim 9, characterized in that in step a) the current shadow ( 14 ), the at least one photovoltaic module ( 04 ) due to its inclination with the module height angle ( 09 ) is caused on the surfaces behind it in the direction of irradiation, is determined or derived as a sun-state-dependent process parameter, and in step b) the calculation of an actual difference angle ( 16 ) depending on the current shadow ( 14 ) he follows. A method according to claim 10, characterized in that the calculation of the current differential angle ( 16 ) depending on the shadow ( 14 ) is done in such a way that the shadow ( 14 ) of a photovoltaic module ( 04a ) due to the positioning of the frame ( 03 ) with the difference angle ( 16 ) no partial shade ( 24 ) on a photovoltaic module lying behind in the direction of irradiation ( 04b ) caused. Method according to claim 11, characterized in that the calculation of the actual difference angle ( 16 ) depending on the shadow ( 14 ) is done in such a way that the shadow ( 14 ) of the photovoltaic module ( 04a ) due to the positioning of the frame ( 03 ) causes a shadow with the difference angle whose outer limit ( 17 ) permanently at the lower end ( 18 ) of the photovoltaic module lying behind in the direction of irradiation ( 04b ) lies. Method according to one of claims 9 to 12, characterized in that in step a) the current reflection ( 22 ) to at least one photovoltaic module ( 04 ), which by reflection of sun rays ( 11 ) on at least one reflection element ( 21 ), is determined or derived, and in step b) the calculation of an actual difference angle ( 16 ) depending on the current reflection ( 22 ) he follows. Method according to claim 13, characterized in that the calculation of the actual difference angle ( 16 ) depending on the reflection ( 22 ) such that the reflection ( 22 ) of the reflection element ( 21 ) the respectively assigned photovoltaic module ( 04 ) over the entire photovoltaic area. Method according to claim 13, characterized in that the calculation of the actual difference angle ( 16 ) depending on the reflection ( 22 ) such that the reflection ( 22 ) of the reflection element ( 21 ) the respectively assigned photovoltaic module ( 04 ) did not shine.