METHOD FOR INCREASING THE ENERGY OUTPUT OF AN ALREADY INSTALLED SOLAR POWER PLANT, SOLAR POWER PLANT RETROFITTING SYSTEM AND SOLAR POWER PLANT

Abstract

A method for increasing the energy output of an already installed solar power plant is provided including at least one first solar panel, which is absorbing sunlight in a first frequency band, wherein a semi-transparent second solar panel, which absorbs light in a second frequency band, is mounted on top of at least one of the at least one first solar panel and connected to a power electronics device of the solar power plant including at least one solar inverter, wherein the first and second frequency bands do not or only partially overlap such that the second solar panel allows at least a part of the light of the first frequency band to pass.

Claims

1. A method for increasing an energy output of an already installed solar power plant comprising at least one first solar panel, which is absorbing sunlight in a first frequency band, wherein at least one semi-transparent second solar panel, which absorbs light in a second frequency band, is mounted on top of at least one of the at least one first solar panel and connected to a power electronics device of the solar power plant comprising at least one solar inverter, wherein the first frequency band and the second frequency bands do not or only partially overlap such that the at least one semi-transparent second solar panel allows at least a part of a light of the first frequency band to pass, the method comprising: for at least one of the at least one semi-transparent second solar panel, installing an electronic adaptation device, which disables the at least one semi-transparent second solar panel or reduces an output when a power input capacity of the power electronics device is exceeded.

2. The method according to claim 1, wherein the at least one first solar panel comprises silicon solar cells and/or the at least one semi-transparent second solar panel comprises perovskite solar cells.

3. The method according to claim 1, wherein the at least one semi-transparent second solar panel, which comprises at least one positive terminal and at least one negative terminal, is connected to the power electronics device at least partly using a separate cable to a cable of the at least one first solar panel.

4. The method according to claim 1, wherein, before the at least one semi-transparent second solar panel is put into operation, the at least one inverter is replaced or supplemented by at least one new inverter to increase a power input capacity of the power electronics device.

5. The method according to claim 1, wherein the at least one first solar panel is only partly covered by the at least one semi-transparent second solar panel and/or an orientation of the at least one first solar panel and the at least one semi-transparent second solar panel is changed to match a power input capacity of the power electronics device.

6. The method according to claim 1, wherein the at least one first solar panel has a sun tracking unit for orienting the at least one first solar panel according to a current position of the sun, wherein a control program for a sun tracking unit is modified depending on a power input capacity of the power electronics device.

7. The method according to claim 1, wherein the electronic adaptation device comprises an attenuator and/or a shortcut switch.

8. A solar power plant retrofitting system for a solar power plant having at least one first solar panel, which absorbs light in a first frequency band, the solar power plant retrofitting system comprising at least one semi-transparent second solar panel, which absorbs light in a second frequency band, to be mounted on top of at least one of the at least one first solar panel and a connection means to connect the at least one semi-transparent second solar panel to a power electronics device of the solar power plant comprising at least one solar inverter, wherein the first frequency band and the second frequency bands do not or only partially overlap such that the at least one semi-transparent second solar panel allows at least a part of a light of the first frequency band to pass, wherein at least one of the at least one semi-transparent second solar panel comprises an electronic adaptation device to disable the at least one semi-transparent second solar panel or to reduce an output when a power input capacity of the power electronics device of the solar power plant is exceeded.

9. The solar power plant retrofitting system according to claim 8, wherein the at least one semi-transparent second solar panel comprises perovskite solar cells.

10. The solar power plant retrofitting system according to claim 8, wherein the at least one semi-transparent second solar panel comprises at least one positive terminal and at least one negative terminal and the connection means comprise at least one cable for connection to the power electronics device.

11. The solar power plant retrofitting system according to claim 8, wherein at least one of the at least one semi-transparent second solar panel is dimensioned to only partly cover the at least one first solar panel.

12. The solar power plant retrofitting system according to claim 8, wherein the electronic adaptation device comprises an attentuator and/or a shortcut switch.

13. A solar power plant having been retrofitted using a solar power plant retrofitting system according to claim 8 and/or the method.

14. The solar power plant according to claim 13, wherein the at least one first solar panel comprises silicon solar cells.

Description

BRIEF DESCRIPTION

[0034] Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

[0035] FIG. 1 shows a principle drawing of an already installed solar power plant;

[0036] FIG. 2 shows a solar power plant retrofitting system according to embodiments of the invention;

[0037] FIG. 3 shows a schematical drawing explaining fundamental steps of a method according to embodiments of the invention;

[0038] FIG. 4 shows a first solar panel oriented with respect to the sun;

[0039] FIG. 5 shows a combination of first and second solar panels and their orientation with respect to the sun;

[0040] FIG. 6 shows an embodiment of an interface of a second solar panel; and

[0041] FIG. 7 shows a graph showing solar power production and tracking angle over time of a day.

DETAILED DESCRIPTION

[0042] FIG. 1 is a principle drawing of an embodiment of an already installed, operational solar power plant 1. The solar power plant 1 comprises multiple first solar panels 2, each comprising multiple solar cells 3. In this embodiment, the solar cells 3 are silicon solar cells, that is, the solar panel 2 is silicon-based.

[0043] The solar system 1 may also comprise a rack or stand 4 for the solar panels 2, for example for positioning them in a certain orientation on the ground or, in other cases, on a roof or the like. Optionally, the rack or stand 4 may comprise a sun tracking unit 5 to change orientation of the solar panel 2 over time according to the current position of the sun.

[0044] The solar panels 2 may further comprise an interface 6, for example a junction box, which has, not shown in FIG. 1, at least one positive terminal and at least one negative terminal. These terminals can be used to connect cable 7, which connects the solar panel 2 to a power electronics device 8, in particular to at least one solar inverter 9 of the power electronics device 8. The power electronics device 8 may comprise further components, for example a transformer 10. The power electronics device 8 connects the solar power plant 1 to an electric grid 11.

[0045] The operation of the solar power plant 1 may be controlled a central control device 12, usually associated with or integrated into the power electronics device 8. The power electronics device 8 may, for example, be provided in a dedicated building, or, regarding smaller solar power plants, in a cabinet or the like.

[0046] FIG. 2 shows a solar power plant retrofitting system 13 according to embodiments of the current invention, which can be used to increase efficiency of power conversion of sunlight to electrical power and thus energy output of an already-installed and operational solar power plant 1. The solar power plant retrofitting system 13 comprises second solar panels 14, 15, which may have different sizes, wherein, in this case, the second solar panels 14 cover the complete light incidence surface of a first solar panel 2 and the second solar panels 15 only cover half of the light incidence surface of a first solar panel 2. The second solar panels 14, 15, are semi-transparent in the sense that at least a first frequency band of the solar spectrum absorbed and converted by the solar cells 3 of the first solar panels 2 is, at least partially, transmitted through the second solar panels 14, 15, whose solar cells 16 absorb a second frequency band of the solar spectrum, which does not (or only slightly) overlap with the first frequency band, for electric power generation In this embodiment, the solar cells 16 of the second solar panels 14, 15 are perovskite solar cells, whose band gap has been tuned such that the perovskite-based absorber material absorbs in the second frequency band. The second solar panels 14, 15 further comprise an interface 17 having at least one positive and at least one negative terminal.

[0047] In an exemplary concrete embodiment, the silicon solar cells 3 may use a first frequency band in the visible to infrared spectrum, for example 500-800 nm wavelength, such that the perovskite solar cells 16 may use a second frequency band, for example, in the ultraviolet spectrum.

[0048] Due to the semi-transparent configuration of the second solar panels 14, 15, they may be installed on top of the first solar panels 2 to yield an increased efficiency for the combination of the two panels 2 and 14, 15. For example, the semi-transparent second solar panel 14 may transmit 97-98% of the sunlight in the first frequency band to the first solar panel 2, wherein the shadowing effect of 2-3% is overcompensated by the electrical power generated by the second solar panel by absorbing sunlight in the second frequency band. In summary, a power conversion efficiency increase is provided by retrofitting the first solar panel 2 of the already operational and installed solar power plant 1 with second solar panels 14, 15 of the solar power plant retrofitting system 13. To mount the second solar panels 14, 15 onto the first solar panel 2, the solar power plant retrofitting system 13 further comprises fixing means 18, which are exemplarily shown as brackets, but may also comprise glue, framing profiles and the like. To connect the second solar panels 14, 15 to the power electronics device 8, in particular the at least one solar inverter 9, connection means 19, in particular cables 20, may further be part of the solar power plant retrofitting system 13.

[0049] FIG. 3 illustrates basic steps of a method according to embodiments of the invention, wherein a solar power plant retrofitting system 13 is used to retrofit a solar power plant 1 already in operation, hence increasing the energy output. As can be seen on the left, a second solar panel 14 is installed on top of the first solar panel 2 according to arrow 21, such that, as shown on the right of FIG. 3, a combination 22 of solar panels 2, 14 results, with the first solar panel 2 underneath the second solar panel 14 mounted on top of the first solar panel 2. If the power transport capacity, in this case the current capacity, of the already existing cables 7 would be exceeded by connecting both panels 2, 14 of the combination 22 to the inverter 9, the cable 20 may be used to fully connect the second solar panel 14 to the inverter 9, as indicated by the dashed line 23. If, however, the already existing cable 7 is configured to carry the current of both solar panels 2, 14, a shorter cable 20 may be used to connect to the cable 7, as indicated by the dotted line 24.

[0050] While some solar power plants 1 may not use the full power input capacity of their at least one solar converter 9, such that the additional power generated by the second solar panels 14, 15 may be accepted at all times, in some cases, there may be a risk of temporarily exceeding the power input capacity of the at least one solar converter 9 of the already-installed solar power plant 1. In such a case, embodiments of the invention propose multiple approaches, which may also be used additionally, that is, complementing each other. For example, as has already been explained with regard to FIG. 2, for at least a part of the first solar panels 2, smaller second solar panels 15 may be used, reducing the amount of additional electric power generated. However, it is also conceivable to only retrofit a part of the first solar panels 2 with second solar panels 14, 15. In particular, the number of solar panels 2 to be retrofitted and the size of the respective second solar panels 14, 15 may specifically be chosen such that the peak power generation expected matches the maximum power input capacity of the power electronics device 8, in particular the at least one solar inverter 9. It is noted that, in another approach, a previously installed solar inverter 9 may also be replaced or a new solar inverter 9 added to increase the maximum power input capacity of the power electronics device 8.

[0051] FIGS. 4 and 5 illustrate a further approach. As shown in FIG. 4, the already installed first solar panel 2 of the not yet retrofitted solar power plant 1 has a certain orientation with respect to the sun 25, in particular chosen to maximize power generation over the day. In the case that power generation improvement after mounting the second solar panel 15 cannot be fully utilized due to insufficient inverter power input capacity, the orientation, in particular the angle and spatial configuration, can be modified, as indicated by arrow 26 of FIG. 5 and the adapted orientation of the combination 22 of first solar panel 2 and second solar panel 14. This change in orientation may be effected before or after mounting the second solar panel 14. The change in orientation leads to a lower maximum in the power generation profile of the combination 22 at the peak sunlight hours, however, the power generation may be increased at other times due to a more optimal orientation with respect to the sun 25.

[0052] FIG. 6 shows an approach according to embodiments of the invention for limiting the maximum power output of a combination 22. In the interface 17, in this case, an electronic adaptation device 27 is provided, which may be a short circuit switch and/or an attenuator. The electronic adaptation device 27 may be controlled by a control unit 28 of the interface 17 and/or the control device 12 of the solar power plant 1, to which it may be connected. In any case, information from sensors 29, for example current sensors measuring the electrical current produced by both the first solar panel 2 and the second solar panel 14, 15, may be evaluated to decide whether a limit value is exceeded. In this case, the electronic adaptation device 27 is controlled to reduce power output, i.e. the electrical current provided at positive terminal 30 and negative terminal 31 of interface 17, by attenuation, in particular using a certain electrical resistance, or even short-circuiting the whole second solar panel 14, 15. If a connection to the control device 12 is used, a more sophisticated control method depending on power generation over all combinations 22 (and optionally non-retrofitted first solar panels 2) may also be implemented.

[0053] As already indicated regarding FIG. 1, in some solar power plants 1, sun tracking devices 5 may be used. In another approach to limit the peak power generation of the solar panels 2, 14, 15 according to the maximum power input capacity of the power electronics device 8, the control program for the sun tracking units 5 may also be modified, as exemplarily indicated in the graph of FIG. 7, wherein the curve 32 indicates the power generation of a combination 22 of first and second solar panels 2, 14, 15 over a day. As can be seen, in a time interval 33, a limit 34 is exceeded, if the sun tracking device 5 always optimally follows the position of the sun 25, as indicated by dashed curve 35. If, however, at least in the time interval 33, sun tracking is modified, for example as indicated by curve 36, that is, a non-optimal orientation with respect to the sun 25 is chosen, the generated power may be kept at or below the limit 34. The limit 34 indicates a power generation value which, if complied with by all combinations 22, ensures that the maximum power input capacity or the power electronics device 8 is not exceeded.

[0054] Although the present invention has been disclosed in the form of embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

[0055] For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.