Power Converter for a Solar Panel

Abstract

A solar array power generation system includes a solar array electrically connected to a control system. The solar array has a plurality of solar modules, each module having at least one DC/DC converter for converting the raw panel output to an optimized high voltage, low current output. In a further embodiment, each DC/DC converter requires a signal to enable power output of the solar modules.

Claims

1-19. (canceled)

20. A system comprising: a plurality of photovoltaic modules; an energy storage device; and an inverter coupled to the plurality of photovoltaic modules and the energy storage device, wherein the inverter is configured to: draw photovoltaic power from the plurality of photovoltaic modules, draw stored power from the energy storage device, convert the photovoltaic power and the stored power to alternating-current (AC) power, and provide, via an inverter output, the AC power to a load.

21. The system of claim 20, wherein each photovoltaic module of the plurality of photovoltaic modules comprises a DC-to-DC power converter configured to adjust operation of the photovoltaic module to a maximum power point.

22. The system of claim 20, wherein the plurality of photovoltaic modules and the energy storage device are connected to an input of the inverter.

23. The system of claim 20, wherein the system is configured to operate in a first mode and a second mode, and wherein: in the first mode the inverter is configured to draw the photovoltaic power from the photovoltaic modules, convert the photovoltaic power to the AC power, and provide the AC power to the load; and in the second mode the inverter is configured to draw the stored power from the energy storage device, convert the stored power to the AC power, and provide the AC to the load.

24. The system of claim 23, wherein: in the first mode, the energy storage device is configured to charge; and in the second mode, the energy storage device is configured to discharge.

25. The system of claim 23, wherein the system is configured to: provide, in the first mode, additional AC power from a utility grid to the load, and switch to the second mode based on an interruption of the additional AC power from the utility grid to the load.

26. The system of claim 25, wherein, in the second mode during the interruption of the additional AC power, the stored power drawn by the inverter is sufficient to meet a power demand of the load for at least twenty seconds.

27. The system of claim 25, further comprising an electrical switch, wherein in the second mode, the inverter is configured to draw the stored power from the energy storage device before the electrical switch is actuated.

28. The system of claim 27, wherein, based on the electrical switch being actuated, the plurality of photovoltaic modules are configured to adjust the photovoltaic power to meet a power demand of the load.

29. The system of claim 23, wherein the system is configured to operate as an uninterruptible power supply.

30. The system of claim 23, wherein the energy storage device is a capacitor.

31. The system of claim 23, wherein the energy storage device is a battery.

32. The system of claim 23, wherein the energy storage device has a nominal 48V output.

33. A system comprising: a plurality of photovoltaic modules, an energy storage device, and an inverter; wherein: the inverter is configured to convert photovoltaic direct-current (DC) power received from the plurality of photovoltaic modules and interim DC power received from the energy storage device to alternating-current (AC) power, and provide the AC power to a load; and the energy storage device is configured to: based on additional AC power received by the load from a utility grid, charge to store the interim DC power from additional photovoltaic DC power received from the plurality of photovoltaic modules; and based on an interruption of the additional AC power to the load from the utility grid, discharge the interim DC power to the inverter.

34. The system of claim 33, wherein the interim DC power is sufficient to meet a power demand of the load while the additional AC power is interrupted.

35. The system of claim 34, wherein the interim DC power is sufficient to meet the power demand of the load for at least twenty seconds.

36. The system of claim 35, wherein the energy storage device is a capacitor or a battery.

37. The system of claim 34, further comprising an electrical switch, wherein: the energy storage device is configured to discharge the interim DC power to the inverter before actuation of the electrical switch; and the plurality of photovoltaic modules is configured to meet the power demand of the load after the actuation of the electrical switch.

38. The system of claim 34, wherein: the plurality of photovoltaic modules is configured to meet the power demand of the load after the interim DC power is discharged by the energy storage device to the inverter.

39. The system of claim 38, wherein the system is configured to provide an uninterrupted supply of the AC power sufficient to meet the power demand of the load before and after the interruption of the additional AC power to the load from the utility grid.

40. The system of claim 33, wherein each of the plurality of photovoltaic modules comprises a solar panel and a DC-to-DC power converter configured to adjust operation of the solar panel a maximum power point.

41. A method comprising: generating, with a plurality of photovoltaic modules, photovoltaic DC power; discharging, from an energy storage device, interim DC power; converting, with an inverter, the interim DC power and the photovoltaic DC power to an alternating-current (AC) power; and providing the AC power to a load.

42. The method of claim 41, wherein the energy storage device and the plurality of photovoltaic modules are connected at a DC input of the inverter.

43. The method of claim 41, further comprising, tracking a maximum power point of each of the plurality of photovoltaic modules.

44. The method of claim 41, further comprising: determining that the load is receiving additional AC power from a utility grid; based on the determining, charging the energy storage device to store the interim DC power from additional photovoltaic DC power received from the plurality of photovoltaic modules; and detecting an interruption of the additional AC power from the utility grid to the load, wherein the discharging, from the energy storage device, of the interim DC power is based on the detecting of the interruption.

45. The method of claim 44, wherein the discharging of the interim DC power from the energy storage device is sufficient to meet a power demand of the load during the interruption of the additional AC power from the utility grid to the load.

46. The method of claim 45, wherein the discharging of the interim DC power from the energy storage device is sufficient to meet the power demand of the load during the interruption of the additional AC power from the utility grid to the load for at least twenty seconds.

47. The method of claim 45, further comprising: adjusting, with the plurality of photovoltaic modules, the photovoltaic DC power to meet the power demand of the load after the interim DC power is discharged and during the interruption of the additional AC power from the utility grid to the load.

48. The method of claim 47, further comprising: actuating an electronic switch, wherein the adjusting is in response to the actuating.

49. The method of claim 47, further comprising: providing an uninterrupted supply of the AC power sufficient to meet the power demand of the load before and after the interruption of the additional AC power from the utility grid to the load.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] So that those having ordinary skill in the art to which the disclosed system appertains will more readily understand how to make and use the same, reference may be had to the drawings wherein:

[0025] FIG. 1 is a schematic diagram of a conventional solar panel array installation;

[0026] FIG. 2 is a schematic diagram of a solar panel army installation constructed in accordance with the subject disclosure; and

[0027] FIG. 3 is a schematic diagram of another solar panel army installation constructed in accordance with the subject disclosure.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0028] The present invention overcomes many of the prior art problems associated with solar arrays. The advantages, and other features of the systems and methods disclosed herein, will become more readily apparent to those having ordinary skill in the art from the following detailed description of certain preferred embodiments taken in conjunction with the drawings which set forth representative embodiments of the present invention and wherein like reference numerals identify similar structural elements.

[0029] Referring to FIG. 2, an improved solar array power generation system is referred to generally by the reference numeral 110. As will be appreciated by those of ordinary skill in the pertinent art, the system 110 utilizes some similar components as the system 10 described above. Accordingly, like reference numerals preceded by the numeral “1” are used to indicate like elements whenever possible. The system 110 includes a roof mounted solar array 120 electrically connected to a control system 140. The solar array 120 has a plurality of solar modules 130a-n. Each solar module 130a-n has a corresponding DC/DC converter 131a-n for converting the raw panel output to a nominal 400 VDC output. Thus, the modules 130 may be easily connected in parallel and, in turn, connected to the control system 140 by a relatively small, safe, high voltage, low current cable (not shown). The resulting 400 VDC level is more suitable for the creation of 120 or 240 VAC than, for example, a 12 VDC car battery. Another advantage realizable by use of the converters 131 is that relatively high switch frequencies can be employed to significantly reduce the size and filtering requirements of the system 110.

[0030] In a further embodiment, the DC/DC converters 131 include MPPT. The DC/DC converter 131 with MPPT maximizes the module output according to the present operating conditions of the solar module 130. For example, module 130a may be temporarily shaded by a cloud or object while module 130c is receiving direct sunlight. Under such circumstances, the performance characteristics of panels 130a and 130c would be different, e.g., the optimum power settings for each panel would not be the same. The corresponding DC/DC converters 131a and 131c would uniquely adjust the module's operation such that modules 130a and 130c will produce the maximum power possible individually. Accordingly, the maximum power output of the solar array 120 is maximized and fewer modules 130 may be employed to produce comparable power to prior art systems.

[0031] In a preferred embodiment, each module 130 contains thirty-two cells divided into two groups of sixteen. A diode (not shown) is commonly disposed between each group of sixteen cells to prevent reverse current flow during shady conditions and other events which may cause variation in panel output. A plurality of DC/DC converters 131 regulate the output of each group of sixteen cells of the module 130 by picking up the output at the diode. Thus, the advantages of the subject disclosure may be utilized in new and existing solar modules by retrofit. In still another embodiment, the DC/DC converters 131 are connected to maximize the output of each cell of the module 130.

[0032] In a further embodiment, the DC/DC converters 131 are also configured to require a signal from the control system 140 to output power. If the panel 130 is not receiving this signal, then the default mode of no power output is achieved. Consequently, installers can handle panels 130 on a sunny day without concern for the live power generated thereby.

[0033] The control system 140 is also improved by further simplification in the preferred system 110. The control system 140 includes a central inverter 144 having a single DC/AC inverter 147. The DC/AC inverter 147 prepares the raw power from the solar array 120 for use by the load 126 or sale to the utility company via the utility grid 128. In the preferred embodiment, the inverter 147 is a relatively simple, low dynamic range, off-the-shelf high voltage inverter for dropping the voltage down and creating the desired frequency. Since the DC/DC converters 131 regulate the power outage from the solar panels 130, the control system 140 can be optimized for efficiency since a very small input voltage range is required for operation. In an embodiment where the solar array 120 outputs 400 VDC, a standardized inverter 147 can be used to beneficially and significantly reduce the wiring complexity and, thereby, the cost of the control system 140. In a further embodiment, galvanic isolation can be maintained in the standardized inverter 147. Accordingly, the control system 140 is further simplified.

[0034] Referring now to FIG. 3, as will be appreciated by those of ordinary skill in the pertinent art, the system 210 utilizes the same principles of the system 110 described above. Accordingly, like reference numerals preceded by the numeral “2” instead of the numeral “1”, are used to indicate like elements. An optional energy storage device 250 is disposed between the control system 240 and the solar array 220. In one embodiment, the energy storage device 250 is a high voltage flywheel energy storage system which ideally operates at 400V. Accordingly, the output of the DC/AC inverter 247 is matched to optimize the operating efficiency of the high voltage flywheel. Acceptable 6 kWh high voltage energy flywheels are available from Beacon Power Corporation in Wilmington, Mass. In another embodiment, the energy storage device 250 is a conventional battery.

[0035] In still another embodiment, the energy storage device 250 is a capacitor and the system 210 acts as an uninterruptible power supply. The capacitor 250 charges during normal operation as the solar array 220 and utility grid 228 provide power to the load 226. In a system with a conventional battery, such operation would shorten the life of the battery as is known to those of ordinary skill in the pertinent art. However, with a capacitor such short life is avoided.

[0036] During an interruption of utility grid power, the capacitor discharges to provide interim power to the load 226 until an electronic switch (not shown) can be actuated to allow the solar array 220 to meet the demand of the load 226. It is envisioned that the capacitor will be able to meet the demand for at least twenty seconds although advantages would be provided by a capacitor with only a few seconds of sustained power output. Thus, the power output from the solar array 220 can still be accessed even when the utility grid 228 is down. In a further embodiment, the capacitor is what is commonly known as an electro-chemical capacitor or ultra capacitor. The capacitor may be a carbon-carbon configuration, an asymmetrical carbon-nickel configuration or any suitable capacitor now known or later developed. An acceptable nominal 48V, 107F ultra capacitor is available from ESMA of the Troitsk Moscow Region in Russia, under model no. 30EC104U.

[0037] In another embodiment, an alternative energy source such as a conventional fuel burning generator, fuel cell or other suitable alternative acts as a backup in combination with a solar array.

[0038] While the invention has been described with respect to preferred embodiments, those skilled in the art will readily appreciate that various changes and/or modifications can be made to the invention without departing from the spirit or scope of the invention as defined by the appended claims.