EA038040B1 - Method (embodiments) and system for increasing the efficiency of a photovoltaic device - Google Patents

Abstract

Provided are methods and system for increasing the efficiency of a photovoltaic device. The system comprises a voltage source means for switching by alternating between applying a voltage signal with a positive magnitude to the photovoltaic device during a first predetermined time interval and suspending application of the voltage signal to the photovoltaic device during a second predetermined time interval. The voltage signal as able to generate an electric field across the photovoltaic device for increasing an output current produced by the photovoltaic device and/or an output power produced by the photovoltaic device.

Description

Cross-reference to related claims

This application claims priority over US Provisional Application No. 61/943127, filed February 21, 2014; US Provisional Application No. 61/943134, filed February 21, 2014; US Provisional Application No. 61/947326, filed March 3, 2014; US Provisional Application No. 62/022087, filed July 8, 2014, the disclosures of which are incorporated by reference in their entirety and for all purposes.

Technology area

The present invention generally relates to photovoltaic devices, and more specifically, but not exclusively, to systems for maximizing the generated power or energy and the overall efficiency of one or more solar cells, for example, by supplying and regulating an external electric field on the solar cells.

Background of the invention

A solar cell (also called a photovoltaic cell) is an electrical device that converts light energy into electricity through a process known as the photoelectric effect. When exposed to light, a solar cell can generate and maintain an electrical current without being connected to any external voltage source. The most common solar cell consists of a pn junction 110 made of semiconductor materials (eg, silicon), such as in solar cell 100 shown in FIG. 1. For example, pn junction 110 comprises a thin wafer composed of an ultrathin layer of n-type silicon on top of a thicker layer of p-type silicon. Where these two layers are in contact, an electric field (not shown) is generated near the top surface of solar cell 100 and diffusion of electrons occurs from a region of high electron concentration (n-type side of pn junction 110) to a region of low electron concentration (p side -type pn-junction 110).

The pn junction 110 is sandwiched between two conductive electrodes 101a, 101b. The top electrode 101a is either transparent to incident (solar) radiation or does not completely cover the top of the solar cell 100. The electrodes 101a, 101b can serve as ohmic metal-semiconductor contacts that are connected to an external load 30 that is connected in series. Although the load is shown only as resistive, load 30 may also contain both resistive and reactive components. Typically, several solar cells 100 can be connected together (in series and / or in parallel) to form a solar cell panel 10 (as shown in FIG. 2). With reference to FIG. 2 shows a typical installation configuration using at least one solar panel 10. The solar cell panels 10 can be connected either in parallel, as shown in FIG. 2, either in series or in a combination of connections and connected to a load such as inverter 31. Inverter 31 may contain both active and reactive components.

Returning to FIG. 1, when a photon hits the solar cell 100, the photon either passes directly through the solar cell material, which typically occurs at lower photon energies; either reflected from the surface of the solar cell; or preferably absorbed by the solar cell material if the photon energy is higher than the band gap of silicon, generating an electron-hole pair.

If a photon is absorbed, its energy is transferred to an electron in the solar cell material. Usually this electron is in the valence band, is closely bound by covalent bonds with neighboring atoms and, therefore, cannot travel far. The energy transferred to the electron by the photon excites the electron into the conduction band, where it can move freely within the solar cell 100. The covalent bond, of which the electron was previously a part, now has one less electron - this is called a hole. The absence of a covalent bond allows the bound electrons of neighboring atoms to move into the hole, leaving behind another hole. Thus, the hole can also efficiently travel through the solar cell 100. Thus, the photons absorbed in the solar cell 100 create movable electron-hole pairs.

The mobile electron-hole pair diffuses or drifts towards the electrodes 101a, 101b. Typically, an electron diffuses / drifts towards the negative electrode and a hole diffuses / drifts towards the positive electrode. Diffusion of carriers (eg electrons) is caused by random thermal motion until the carrier is trapped by electric fields. Carrier drift is caused by the electric fields generated in the active region of the solar cell 100. In thin film solar cells, the predominant type of carrier separation is drift due to the electrostatic field of the pn junction 110 across the entire thickness of the thin film solar cell. However, for thicker solar cells that have virtually no electric field in the active region, diffusion is the predominant type of carrier separation. The diffusion length of minority carriers (i.e., the length that photogenerated carriers can travel before they recombine) must be greater in thicker solar cells.

Ultimately, electrons that are created on the n-type side of pn-junction 110, accumulated at pn-junction 110 and flown to the n-type side, can provide power for external load 30 (via electrode 101a) and return to the p-type side (through the electrode 101b) of the solar cell 100. After returning to the p-type side, the electron can recombine with the hole, which was either created as an electron-hole pair on the p-type side, or flew through the pn junction 110 from the side n-type.

As shown in FIG. 1, the electron-hole pair travels in a circular path from the point of creation of the electron-hole pair to the point where the electron-hole pair accumulates on the electrodes 101a, 101b. Since the path traversed by an electron-hole pair is long, there are enough opportunities for an electron or hole to recombine with another hole or electron, such recombination leads to a loss of current in any external load.30 In other words, when creating an electron-hole pair one of the carriers can reach the pn junction 110 (stored carrier) and contribute to the current generated by the solar cell 100. Alternatively, the carrier can recombine without making a net contribution to the cell current. The recombination charge results in a decrease in quantum efficiency (i.e., the percentage of photons that are converted to electrical current in the case of solar cell 100) and hence the overall efficiency of solar cell 100.

The cost of a solar cell 100 or solar panel 10 is typically quoted in dollars per watt of peak electrical power that can be generated under normalized conditions. Highly efficient solar cells reduce solar energy costs. Many solar system or power plant costs are proportional to the amount of solar cells required as well as the area (land) required to install the panels. A solar cell with a higher efficiency will reduce the number of solar cell panels required for a given power output and the required area for deploying the system. This reduction in the number of panels and the space they occupy could reduce the overall cost of the power plant, even if the elements themselves are more expensive.

The ultimate goal is to make the cost of generating solar energy comparable to or less than traditional power plants that use natural gas, coal and / or fuel oil to generate electricity. Unlike most traditional power generation facilities that require large centralized power plants, solar power systems can be deployed to large centralized locations by utilities on commercial buildings to help recover energy costs, and even on a residential building by location. Recent attempts to reduce costs and improve the efficiency of solar cells include testing different materials and different fabrication technologies used for solar cells. Another approach attempts to enhance the depletion region formed around pn junction 110 to enhance the movement of charge carriers through solar cell 100. For example, see U.S. Patent No. 5,215,599, Hingorani et al. (Hingorani), filed May 3, 1991, and patent US No. 8466582, Fornage (Fornage), filed December 2, 2011, claiming priority as of the filing date of December 3, 2010, the descriptions of which in full and for all purposes are incorporated in this application by reference.

However, these traditional approaches to enhancing the movement of charge carriers through the solar cell 100 require modifications to the basic design of the solar cell 100. Hingorani and Fornage, for example, disclose the application of an external electric field to the solar cell using a modified solar cell design. Applying an external electric field requires a voltage applied between the electrodes, inducing an electric field (described in more detail below with reference to Equation 2). Without changing the basic structure of the solar cell 100, supplying voltage to the existing electrodes 101a, 101b of the solar cell 100 short-circuits the supplied voltage through the external load 30. To put it another way, supplying voltage to the electrodes 101a, 101b of the solar cell 100 is ineffective for generating an external electric field and increasing movement of charge carriers. Accordingly, traditional approaches, such as those disclosed in Hingoriani and Fornage, necessarily modify the basic design of the solar cell 100, for example, by inserting an external (and electrically insulated) set of electrodes into the base of the solar cell 100. There are several disadvantages to this approach.

For example, external electrodes must be placed on the solar cell 100 during the manufacturing process, it is practically impossible to modify the external electrodes on an existing solar cell or panel. This modification of the manufacturing process significantly increases production costs and decreases production yield. In addition, placing external electrodes located on the face or the side on which the rays are incident of the solar cell 100 reduces the optical energy that reaches the solar cell 100, thereby resulting in a lower output power.

As a further disadvantage, significant voltages must be applied to the outer electrodes of the solar cell 100 to result in significant improvements in the output power of the solar cell 100. Fornage, for example, discloses that voltages of the order of 1000 V must be applied to the external electrodes for the applied electric field to be effective and to increase the output power of the solar cell 100. The magnitude of this voltage requires special training for maintenance, as well as additional high-voltage equipment and wiring that does not currently exist in existing or new solar panel systems. As an example, an insulating layer between the outer electrodes and the solar cell 100 must be sufficient to withstand the high applied voltage. In the event of a failure of the insulating layer, there is a significant risk of damage not only to the solar cell 100, but also to all solar cell panels 10 connected in series or parallel with respect to the failed solar cells, as well as to the external load 30 (or inverter 31).

As an additional disadvantage, different lighting conditions (eg, due to clouds covering the sun and / or normal weather fluctuations) can cause instability in the power output of conventional solar cells and solar cell panels. For example, referring to FIG. 2, the inverter 31 generally requires a static, unchanging input voltage and current. As shown in FIG. 2, the solar panels 10 provide the input voltage and current to the inverter 31. However, time varying lighting conditions can cause the output power of the solar panels 10 to fluctuate (eg, on the order of a few seconds or less).

The fluctuation of the voltage and current supplied to the inverter 31 reduces the quality of the output power by the inverter 31, for example, in terms of frequency, voltage and harmonic content. Traditional measures to combat changing lighting conditions involve placing batteries or capacitors at the input of the inverter 31 and, unfortunately, only minimizes these changes.

In view of the above, there is a need for an improved solar cell system and method for increasing efficiency and power output, for example, by increasing the mobility of electron-hole pairs in order to overcome the aforementioned difficulties and disadvantages of conventional solar cell systems.

The essence of the invention

The present invention relates to systems for optimizing the power output of a photovoltaic device. In accordance with a first aspect disclosed in this application, a method for controlling a photovoltaic device is described, the method including supplying a first component of a voltage signal to the photovoltaic device, the first component representing an on state for generating an external electric field on the photovoltaic device; and supplying a second component of the voltage signal to the photovoltaic device, the second component representing a shutdown cycle.

In some embodiments of the disclosed method, supplying the first component includes supplying a high voltage with a time varying voltage pulse from a circuit of the voltage pulse generating device, and supplying the second component includes disabling the circuit of the device for generating voltage pulses.

In some embodiments of the disclosed method, supplying the first component includes connecting the voltage source and the photovoltaic device in a first position of a switch located between the voltage source and the photovoltaic device, and wherein said supplying the second component includes disconnecting the voltage source and the photovoltaic device in the second position switch. In some embodiments of the disclosed method, the method further includes monitoring the output voltage of the photovoltaic device with a voltage sensor connected in parallel to the photovoltaic device, and monitoring the output current of the photovoltaic device using a current sensor connected in series between the photovoltaic device and a load supplied by the photovoltaic device.

In some embodiments of the disclosed method, the method further includes adjusting, by a control circuit connected to the voltage source, at least one of the magnitude, duration, and frequency of the first component to maximize output power based on said tracking.

In accordance with another aspect disclosed in this application, a method for controlling a photovoltaic device is disclosed, including: providing connection of a voltage source to the photovoltaic device;

supplying a voltage signal generated by the voltage source to the photovoltaic device, the voltage signal having a first state for generating an external electric field on the photovoltaic device and a second state representing a shutdown cycle.

In some embodiments of the disclosed method, providing a voltage source includes providing at least one of the following:

circuitry for generating voltage pulses for connection to a photovoltaic device to provide a time-varying voltage pulse across the photovoltaic device, the time-varying voltage pulse providing a first state and a second state;

switch for connection between the voltage source and the photovoltaic device, the switch connects the voltage source and the photovoltaic device in the first position to generate the first state and disconnects the voltage source and the photovoltaic device in the second position to generate the second state.

In some embodiments of the disclosed method, applying a voltage signal includes applying an output voltage of a high voltage source of a circuit of a voltage pulse generating device to a photovoltaic device when a switching transistor of a circuit of a voltage pulse generating device is in an on state to generate a first state and continuing said application. the output voltage of the high voltage source until the pulse generator of the circuit of the voltage pulse generating apparatus turns the switching transistor into an off state to generate a second state.

In some embodiments of the disclosed method, the method further includes providing connection of the control circuit to at least one of the following: a switch and a circuit for generating voltage pulses.

In some embodiments of the disclosed method, the method further includes providing a voltage sensor connected in parallel with the photovoltaic device to monitor the output voltage of the photovoltaic device, and connecting a current sensor in series between the photovoltaic device and the photovoltaic device load to monitor the output current of the photovoltaic device.

In some embodiments of the disclosed method, the method further includes monitoring the output voltage and the output current, and adjusting, with the control circuit, the magnitude of the first state to maximize the output power based on said tracking.

In some embodiments of the disclosed method, applying a voltage signal includes generating an external electric field with at least one of a first direction or a second direction, wherein the first direction and polarity of the internal electrodes of the photovoltaic device are in the same direction to increase the power output of the photovoltaic device, and the second direction is in the opposite direction to the polarity of the inner electrodes to reduce the power output.

In some embodiments of the disclosed method, providing a voltage source includes providing a voltage source connected to at least one of the following: a solar cell, solar cell array, solar cell array, and solar cell array.

In accordance with another aspect disclosed herein, a method for controlling a photovoltaic device is disclosed, including: providing connection of the device for generating voltage pulses to the photovoltaic device;

supplying a voltage signal generated by the voltage pulse generating device to the photovoltaic device, the voltage signal having a first state for generating an external electric field on the photovoltaic device and a second state representing a shutdown cycle.

In some embodiments of the disclosed method, applying a voltage signal includes applying an adjustable voltage to a photovoltaic device.

In some embodiments of the disclosed method, the method further includes connecting one or more inductors in series between the voltage pulse generating device and the photovoltaic device load to block frequencies of the voltage signal to the load that are greater than a predetermined frequency.

In some embodiments of the disclosed method, the method further includes controlling at least one of the frequency and duration of the first state and the second state, using a control circuit connected to the device for generating voltage pulses.

In accordance with another aspect disclosed in this application, there is disclosed a method for controlling a photovoltaic device, including: providing connection of a first port of the switch to the photovoltaic device;

providing connection of the second port of the switch to the load supplied by the photovoltaic device;

providing connection of the third port of the switch to the voltage source, and the switch can operate in the first position with the establishment of a current path between the photovoltaic device and the voltage source and in the second position with the establishment of a current path between the photovoltaic device and the load;

- 4 038040 supplying a voltage signal generated by a voltage source to the photovoltaic device when the switch is in the first position, the voltage signal having a first state for generating an external electric field on the photovoltaic device when the switch is in the first position and a second state for providing electrical isolation between the voltage source and the load when the switch is in the second position.

In some embodiments of the disclosed method, providing a first switch port connection includes providing a first switch port to a photovoltaic device.

In some embodiments of the disclosed method, the method further includes controlling at least one of the frequency and duration of switching between the first position and the second position with a switch controller connected to the dip switch.

In some embodiments of the disclosed method, the method further includes providing connection of a device to reduce any voltage attenuation of the first component between the load and the photovoltaic device.

In some embodiments of the disclosed method, applying a voltage signal includes applying an adjustable voltage to a photovoltaic device.

In some embodiments of the disclosed method, the method further includes controlling at least one of the following: frequency, magnitude and duration of the first state and the second state using a control circuit connected to a voltage source and a switch based on the output current of the photovoltaic device measured by the sensor current connected in series between the photovoltaic device and the load, and the output voltage of the photovoltaic device measured by a voltage sensor connected in parallel to the photovoltaic device.

Brief description of graphic materials

FIG. 1 is an exemplary top level cross-sectional view illustrating an embodiment of a prior art solar cell.

FIG. 2 is an exemplary high-level block diagram illustrating one embodiment of a prior art solar cell array using the solar cells shown in FIG. one.

FIG. 3 is an exemplary high-level block diagram illustrating an embodiment of a solar cell control system.

FIG. 4 is an exemplary block diagram illustrating an alternative embodiment of the solar cell control system shown in FIG. 3, in which the array of solar panels is connected to a voltage source through a switch.

FIG. 5A-D show exemplary waveforms at the inputs and outputs of a switch used with the solar cell array shown in FIG. 4 illustrating applied voltage versus time.

FIG. 6 is an exemplary block diagram illustrating yet another alternative embodiment of the solar cell driving system shown in FIG. 3, in which an array of solar cell panels is connected to the circuit of a voltage pulse generating device.

FIG. 7 illustrates an exemplary waveform used with the solar array array of FIG. 6 illustrating applied voltage versus time.

FIG. 8 is an exemplary block diagram illustrating one embodiment of the circuit of the voltage pulse generating apparatus shown in FIG. 6.

FIG. 9A is an exemplary block diagram illustrating an alternative embodiment of the solar cell driving system shown in FIG. 4, in which the solar cell control system includes a control circuit.

FIG. 9B is an exemplary block diagram illustrating a state diagram for the control circuit shown in FIG. 9A.

FIG. 10A is an exemplary block diagram illustrating an alternative embodiment of the solar cell driving system shown in FIG. 6, in which the solar cell control system comprises a control circuit.

FIG. 10B is an exemplary block diagram illustrating a state diagram for the control circuit shown in FIG. 10A.

FIG. 11A-C are exemplary waveforms illustrating an embodiment of the improved output current relationship of the photovoltaic device shown in FIG. 3 on the applied voltage, pulse repetition rate and pulse duration.

It should be noted that the figures are not to scale, and that elements of similar structures or functions are generally identified with the same reference numerals for purposes of illustration.

- 5 038040 all shapes. It should also be noted that the figures are only intended to facilitate describing the preferred embodiments. These figures do not reflect every aspect of the described embodiments and do not limit the scope of the present invention.

Detailed Description of Preferred Embodiments

Since currently available solar cell systems cannot maximize the output power of a photovoltaic cell, a solar cell system that increases the mobility of electron-hole pairs and reduces the current during recombination in a semiconductor material may be in demand and provide the basis for a wide range of solar cell systems with in order to increase the efficiency and output power of solar cells made in the form of a solar cell panel. This result can be achieved in accordance with one embodiment disclosed herein with a solar cell control system 3 00 as shown in FIG. 3.

Referring to FIG. 3, the solar cell control system 300 is suitable for use with a wide range of photovoltaic devices. In one embodiment, the solar cell control system 300 may be suitable for use with the solar cell 100 shown in FIG. 1. For example, solar cell 100 can represent any suitable generation of solar cells, such as crystalline silicon-based cells (first generation), thin-film solar cells including amorphous silicon cells (second generation), and / or third-generation cells. The solar cell control system 300 can advantageously be used with any generation of solar cell 100 without structural changes and associated disadvantages. In another embodiment, the solar cell control system 300 may be suitable for use with multiple solar cells 100, such as the solar cell panels 10 shown in FIG. 2. As previously discussed, multiple solar cells 100 can be connected (in series and / or in parallel) together to form a solar cell panel 10. Solar panels 10 can be mounted on a support structure (not shown) by ground-based, roof-mounted, sun-tracking systems, fixed rods, and so on, and can be used for both ground-based and spaceborne devices. Likewise, the solar cell control system 300 can advantageously be used with any generation of solar panel 10 without structural changes to solar panel 10 and associated disadvantages.

As shown in FIG. 3, the photovoltaic device 200 interacts with an electric field 250. In some embodiments, the polarity of the electric field 250 can be applied either in the same direction or in the opposite direction with the polarity of the electrodes 101a, 101b (shown in FIG. 1) in the photovoltaic device 200. For example if the electric field 250 is applied in the same direction as the polarity of the electrodes 101a, 101b in the photovoltaic device 200, the electric field 250 acts on the electron-hole pairs in the photovoltaic device 200, applying a force -e ^- E or h ⁺ E to the electron or hole, respectively, thereby accelerating the mobility of an electron and a hole in the direction of the corresponding electrodes. Alternatively, if the polarity of the electric field 250 is reversed, the mobility of the electron-hole pairs in the photovoltaic device 200 is reduced, thereby increasing the recombination current in the photovoltaic device 200. Accordingly, the efficiency of the photovoltaic device 200 can be reduced as desired, for example, to control the output the power of the photovoltaic device 200. In addition, the electric field 250 supplied to the photovoltaic device 200 can be static or time-varying as desired. In the case where the electric field 250 changes over time, the electric field 250 has a time-averaged value that is different from zero. In other words, the net force acting on the electrons and holes is nonzero to provide increased mobility of the electron-hole pairs of the photovoltaic device 200.

For the conventional solar cell 100 shown in FIG. 1, in the absence of an external load 30 (shown in FIG. 1), an external voltage can be applied to the electrodes 101a, 101b of the solar cell 100 to create an electric field 250. In one embodiment, the electric field 250 (e.g., between electrodes 101a, 101b) is defined by Equation 1:

E = (Equation 7)

In Equation 1, E is the electric field 250, VApp is the voltage applied externally to the photovoltaic device 200, Vp is the output voltage of the photovoltaic device 200 (e.g., ~ 30 V), and t is the thickness of the semiconductor material in the photovoltaic device 200 from electrode 101a to 101b. For example, suppose Va _pp -V _p = 200 V (nominal) and the thickness t is approximately 0.02 cm, the electric field 250 is approximately 10 kV / cm. As can be seen from Equation 1, by decreasing the thickness t of the photovoltaic device 200 (eg, less than 0.01 cm), stronger electric fields 250 can be obtained using the same or lower voltages.

- 6 038040

As discussed above, the photovoltaic device 200 typically supplies an external load, such as the load 30 of the solar cell 100. Referring to Equation 1, if the external voltage VApp is applied directly to the photovoltaic device 200 that powers the external load 30, the external load 30 may contain active components that draw current from the applied voltage source VApp. In other words, applying an external voltage V _App to the photovoltaic device 200 can efficiently deliver power to the common circuit, as represented by Equation 2:

_Input power = (yy (Equation 2)

In Equation 2, RL is the impedance of the external load 30. In some cases, the input power may be significantly greater than the output power of the photovoltaic device 200. Accordingly, the photovoltaic cell control system 300 is configured to supply an electric field 250 to the photovoltaic device 200 without introducing more energy. than the photovoltaic device 200 is capable of producing, or more energy than would be obtained by applying an electric field to the photovoltaic device 200.

The solar cell control system 300 can supply an external voltage VApp to the photovoltaic device 200 using any suitable means described herein, including using a switch 55 as shown in FIG. 4. Referring to FIG. 4, photovoltaic device 200 may represent any number of photovoltaic devices such as solar cell 100 and / or solar cell panels 10 as shown. The solar cell panels 10 are connected to a switch 55, such as a single pole, double throw (or three way) switch, as shown. In one embodiment, switch 55 is also connected to a voltage source 50 and an external load RL (eg, shown as inverter 31). The inverter 31 can convert direct voltage and current to alternating voltage and current, which are generally compatible with the voltage and frequency with conventional AC power grids. The output frequency of the inverter 31 and the AC current / voltage amplitude may vary depending on country, location and local grid requirements.

Voltage source 50 may include any suitable means for maintaining a constant voltage, including ideal voltage sources, controlled voltage sources, and so on. However, in some embodiments, such as the embodiment shown below with reference to FIG. 9A, voltage source 50 may have a modifiable, adjustable output voltage (eg, time varying voltage). A switch control 45 (or controller) is connected to the switch 55 to control the duration of the connection and / or the switching frequency, for example, between the voltage source 50 and the inverter 31 with solar panel 10. Switch controller 45 may be preset to operate with a fixed switching duration D and switching frequency f (shown in FIGS. 5A-C). The voltage supplied in the first position of the switch 55 can be fixed and dependent on the voltage source 50. In some embodiments, the voltage applied by the voltage source 50, the duration D of the connection, and / or the switching frequency f may be predetermined and / or varied depending on the load conditions.

For example, switch 55 connects solar panels 10 to voltage source 50 in a first position (as indicated by the arrow in switch 55 in FIG. 4). When connected in the first position, the voltage source 50 applies a voltage VAPP to the electrodes 101a, 101b (shown in FIG. 1) of the solar panels 10 and induces an electric field 250 (shown in FIG. 3) to each solar panel 10. After the electric field 250 has been generated on the solar panel 10, the switch 55 is switched to connect the solar panels 10 to the inverter 31 (i.e., the load RL) in the second position. Accordingly, the voltage source 50 can provide an electric field 250 without being simultaneously connected to the solar panels 10 and the inverter 31. Thus, again with reference to Equation 2, the application of the external voltage VAPP does not allow the load RL (for example, the inverter 31) to draw current directly from the source 50 voltage.

Applying an electric field 250 to the solar panel 10 can increase the current and output of the solar panels 10 by a predetermined amount when subsequently connecting the solar panels 10 to the inverter 31 in the second position. The predetermined value depends on the intensity of the light incident on the solar panels 10, the voltage VAPP applied to the solar panels 10 by the voltage source 50, the thickness of the solar panels 10, the frequency f with which the voltage source 50 is connected to the solar panels 10, and the factor filling the switching process between the first position and the second position, the duty cycle is defined as the time interval when the solar panels 10 are connected to the voltage source 50, divided by the 1 / f switching time (i.e., multiplied by the frequency f or divided by the entire signal period). It should be noted that the switching time D, switching frequency f, and duty cycle are all such interrelated quantities that determining the values of any two of the quantities allows a third quantity to be determined. For example, setting the switching frequency and duty cycle allows the switching time D to be determined. For example, under high light intensity conditions, the increase in output power can be in the order of 20%; in low light conditions - 50 +%.

The embodiment shown in FIG. 4, advantageously provides an electric field 250 on the photovoltaic device 200 without the need to modify solar cell panels 10 and / or solar cells 100 to provide additional external electrodes. In some embodiments, an energy storage device, such as a capacitor 41, an inductor 42, and / or a battery 43, may be placed in front of the inverter 31 to suppress any voltage dips observed by the inverter 31 while the switch 55 is in the first position. Accordingly, while the inverter 31 (i.e., the load) is disconnected from the solar panels 10, when the switch 55 is in the first position and an electric field 250 is generated on the solar panel 10 (i.e., for the switching time D shown 6A-D), the power storage device powers the inverter 31 to maintain the current flowing during this switching interval. In other words, the energy storage device can be discharged while the solar panels 10 are disconnected from the inverter 31.

Thus, it is not required to continuously apply a constant voltage from the voltage source 50, which in turn creates an electric field 250, in order to see the improvement in the output power of the solar panels 10. For example, with a switching time D of nominally 10-2000 ns, a VApp of nominally 100-500 + V and a switching frequency f of 20 μs, a duty factor of nominally 0.1-10% may be used. Inductor 42, capacitor 41, and / or battery 43 are selected to be of sufficient size to provide sufficient discharge while the solar panels 10 are disconnected and an electric field 250 is applied to the solar panels 10 without causing voltage attenuation at the inverter output 31.

For example, the size of the capacitor 41 that is placed in parallel with the load (eg, inverter 31) is determined by the acceptable voltage drop that the inverter 31 can tolerate during the switching time D. For example, if the voltage drop during the switching time D should not be less than 90% of the maximum voltage generated by the photovoltaic device 200, the capacitor should be sized according to Equation 3:

C ₄ i =, ~ ^D --- (Equation 3) ⁴¹ R _L ln (Max7) ^v '

In equation 3: D is the duration of the connection of the switch to the voltage source 50 and MaxV is the required percentage of the maximum voltage, (for example, 90% in the above example). Inductance and / or battery can be calculated in a similar way.

FIG. 5A shows the control voltage of the switch controller 45 versus time for activating and controlling the switch 55 using the photovoltaic cell driver system 300 shown in FIG. 4. In this example, solar panels 10 are disconnected from inverter 31 and connected to voltage source 50 in a first position of switch 55 for a duration D that repeats every 1 / f s. FIG. 5B shows the voltage of the voltage source 50 provided by the switch 55 in the first position as a function of time. FIG. 5C shows the output voltage of the switch 55 of the solar panels 10 (in parallel connection) versus time at the output of the switch 55, which is connected to the inverter 31 in the second position. Similarly, in FIG. 5D shows the voltage versus time at the output of the switch 55, which is connected to an inverter 31 having a capacitor 41 connected therebetween.

The voltage drop received by the inverter 31 shown in FIG. 5D, at the end of the switching duration D assumes the voltage drop discussed above. The voltage drop depends on the size of capacitor 41, inductor 42, and / or battery 43. In one example of a system 300 that does not include capacitor 41, inductor 42, or battery 43, the voltage applied to the input of inverter 31 acts as an output voltage shown in FIG. 5C. FIG. 6 depicts an alternative embodiment of the photovoltaic control system 300 shown in FIG. 3. Referring to FIG. 6, photovoltaic device 200 may represent any number of photovoltaic devices such as solar cell 100 and / or solar cell panels 10 as shown. As shown, solar panels 10 are connected in parallel, but can also be connected in series and in any combination of connections.

A voltage pulse generating device 60, such as a high voltage pulse generator, may apply a time varying voltage pulse 71 (as shown in FIG. 7) to one or more solar cell panels 10. In one embodiment, the duration DP of the voltage pulse 71 may be short, nominally 10-2000 ns, and the magnitude may be large, nominally 100-500 + V. In the embodiment shown in FIG. 6, applied voltages, pulse width and pulse repetition rate are clamped to a predetermined level to ensure optimal performance under the selected operating conditions. For example, referring to FIG. 6 and 7, the voltage pulse 71 has a duration DP of approximately 1000 ns, this voltage pulse 71 is repeated with a period of 1 / f. The length DP of the voltage pulse 71 and the frequency f of the voltage pulse 71 are selected such that the reactance of the inductor in the voltage inverter 31 represents a high impedance for the voltage pulse generating device 60, this high impedance allows a high voltage to develop at the electrodes 101a, 101b ( shown in Fig. 1) solar panels 10 and not be short-circuited by the inverter 31.

In addition, inductors in series (not shown) can be placed at the input of the inverter 31, these series inductors are capable of supporting the input current of the inverter 31 and act as a high frequency choke so that the voltage pulses 71 are not attenuated (or actually short-circuited). active component of the inverter 31. The duty cycle (pulse time / pause time) can be nominally 0.1-10%.

The strength of the electric field 250 applied to the photovoltaic device 200 depends on the design of the photovoltaic device 200, for example, the thickness of the photovoltaic device 200, the material and dielectric constant of the photovoltaic device 200, the maximum breakdown voltage of the photovoltaic device 200, etc. For the voltage pulse 71 shown in FIG. 7, Fourier analysis of this waveform results in a train of pulses with frequencies ω = nω _o , where ω _o = 2πf, and the pulse power is given by Equation 4:

oo (Equation 4) sin ηπτ

7 (ω) = 2πτ V _App ) ---- Ζ — ι ηπτ

Η = —οο

In equation 4, n is a series of integers from -da to + yes. Accordingly, the zero-order pulse (i.e. n = 0) has a constant component, which is closed through the resistive load RL. The first order of the voltage pulse 71 applied to the solar panel 10 is V _App (1-DP / f), where DP / f is the duty cycle, DP is the pulse duration, and f is the pulse repetition rate. Since the inductance of the inverter 31 acts as a high impedance Z on the voltage pulse 71 generated according to the embodiment of FIG. 6, a high voltage pulse 71 develops on each of the solar panels 10, which in turn creates a high electric field 250 on the solar panels 10.

As shown in FIG. 6, the voltage inverter 31 is an external load RL. However, the external load RL can contain purely active components, so the set of inductors can be placed in series with the load RL to act as a high frequency choke so that the voltage pulse 71 (and the electric field 250) is applied to the solar panel 10.

Any number of circuits may be used in the voltage pulse generator 60 to deliver the desired voltage pulse 71. One such exemplary circuit used in the voltage pulse generating apparatus 60 is shown in FIG. 8. As shown, the device 60 for generating voltage pulses includes a pulse generator 61 (not shown), a high voltage source 69 (not shown), and a switching transistor 68 for applying a high voltage pulse 71 to the solar panels 10 (for example, switching the output voltage of the source 69 high voltage solar panel 10) shown in FIG. 6. The voltage pulse generating device 60 shown in FIG. 8 includes a device that transmits electrical signals between two electrically isolated circuits using light, such as an optocoupler 62, to isolate the pulse generator 61 from the high voltage switching transistor 68.

Advantageously, the optocoupler 62 prevents a high voltage (eg, from a high voltage source 69) from influencing the pulse signal 71. The optocoupler circuit 62 is shown with pins 1-8 and is shown as part of the input circuitry of the voltage pulse generating device 60.

A bias voltage source 63 (not shown) provides a voltage (for example, 15 VDC) to the optocoupler 62 to provide the necessary bias for the optocoupler 62. Capacitor 64 isolates the bias voltage source 63, creating an AC path for any signal after the bias source is distorted. to optocoupler 62. Pins 6 and 7 of optocoupler 62 are outputs of the switching signal of optocoupler 62 used to drive high voltage switching transistor 68. Diode 66, such as a silicon zener diode, is used to hold the switching threshold of switching transistor 68 above the operating point of diode 66, eliminating any noise from accidentally turning on the switching transistor 68. Resistor 67 sets the bias point for the gate G and emitter E of the switching transistor 68. When the voltage applied to the terminals

9 038040 and 7 of the optocoupler 62 exceeds the threshold set by the resistor 67, the switching transistor 68 opens and a current flows between the collector C and the emitter E of the high voltage switching transistor 68. Accordingly, the high voltage switching transistor 68 provides an applied high voltage for the solar panels 10 until the input control pulse of the pulse generator 61 falls below a set threshold value on G of the high voltage switching transistor 68, which stops current flow through the CG, closing the switching transistor. 68. As with the previous embodiments described above, applying an electric field 250 to the solar panel 10 can increase the current and power output of the solar panels 10 by a predetermined amount when subsequently connected to the inverter 31 (for example, depending on the intensity of the light incident on the solar panel 10, the voltage VAPP supplied to the solar panel 10 from the voltage source 50, the thickness of the solar panels 10, the DP pulse duration and the frequency f with which the voltage pulse 71 is applied to the solar panel 10 s, and so on). Likewise, under high light intensity conditions, the improvement in output power of solar panels 10 can be in the order of 20%; and in low light conditions it can be 50 +%.

The improvement in the performance of the photovoltaic device 200 interacting with the electric field 250 can be measured as an increase in the solar cell short-circuit current, Isc, as shown in Equation 5:

lsc = lease [1 + c (V (T, f), t, ε) * (p _max - p)] (Equation 5) where I _Base is the short-circuit current in the absence of an external electric field 250 and p _max is the maximum power optical radiation, whereby any additional power does not create any additional electron-hole pairs. Since the improvement in the output current of the solar cell is due to the influence of the electric field 250, the form ^c (^ (t, ί) Λ ^ε ) can be described by equation 6:

c (V (t, f), t, ε) = m (t, 8) V _A pp * (1-exp (T / T _o )) * exp (-f _d eca _y / 0 (Equation 6)

In equation 6, m (t, ε) depends on the photovoltaic device 200.

The improvement in the short circuit current I _sc due to the electric field 250 can be linear with the applied voltage V _App . The improvement observed with respect to the pulse repetition rate has a characteristic decay rate (1 / f _decay ) and is exponential with respect to the pulse repetition rate f. The improvement observed in pulse width T can also be exponential and describe how quickly the applied voltage V _App reaches its full value. The improvement observed in the pulse duration T depends on the characteristics of the voltage pulse generating device 60. The increase in short-circuit current I _sc as a function of the applied voltage V _App , pulse repetition frequency f and pulse duration T are shown in FIG. 11A-C, respectively.

FIG. 11A shows the expected improvement in short circuit current I _sc for solar panel 10 (shown in FIG. 2) as a function of the applied voltage pulse VAPP. As shown, the pulse width and pulse repetition rate are fixed, and the pulse voltage varies from 50 to 250 V. The improvement in the short-circuit current ΔI _SC increases nominally from 0.1 to 2 A. The change in the short-circuit current ΔI _SC depending on the applied voltage pulse V _APP for the first order is approximately linear. FIG. 11B shows the change in the improvement of the short circuit current ΔI _SC as a function of the pulse repetition rate for a fixed pulse width and a fixed pulse voltage. As shown in FIG. 11B, the improvement in the short circuit current ΔI _SC decreases from about 1.7 A to about 0.45 A as the pulse repetition rate increases from 10 to 100 in arbitrary units of time. This behavior is roughly exponential. FIG. 11C shows the change in the improvement of the short-circuit current ΔI _SC as a function of the pulse duration at a fixed pulse repetition rate and a fixed voltage pulse. For this example, the improvement in the short-circuit current M _SC increases from 0 to 1.2 A as the pulse width increases with time from 0 to 2000.

In each of the described embodiments, increasing the electric field 250 through the electrodes 101a, 101b of the solar cell 100 or solar panel 10 increases the efficiency of the solar cell 100 or panel 10, for example, up to the maximum electric field strength E _max . In other words, as soon as the electric field strength 250 reaches its maximum strength, the electron-hole recombination rate is minimized. Accordingly, it may be preferable to configure the control circuit of the photovoltaic device 200 to maximize the output current and voltage under various operating conditions.

For example, referring to FIG. 9A, current sensor 33 and voltage sensor 32 are shown connected to the photovoltaic cell control system 300 shown in FIG. 4. As shown, the current sensor 33 is connected in series between the solar panel 10 and the inverter 31. The sensor

- 10 038040 current can track the output current of the solar panel 10. Likewise, a voltage sensor is connected in parallel to the solar panels 10 and the inverter 31 to monitor the output voltage of the solar panel 10.

The control circuit 35 is connected to both the current sensor 33 via the control terminals 33a and to the voltage sensor 32 via the control terminals 32a. The current sensor 33 can be a built-in or inductive metering unit and measures the output current of the solar panels 10. Similarly, the voltage sensor 32 is used to measure the output voltage of the solar panels 10. The product of the current measured by the current sensor 33 and the voltage measured by the voltage sensor 32 is the output power transmitted from the solar panels 10 to the inverter 31. In some embodiments, the voltage sensor 32 may also serve as a power source for the control circuit 35 and only functions as long as the solar panels 10 are illuminated and provide sufficient power to activate the control circuit 35. The control circuit 35 is further connected to the switch 55 to determine the switching times and frequencies, described below with reference to FIG. 4.

The switching times and frequencies can be adjusted to apply the voltage V _App to the solar panel 10 so that both the current generated in the solar cell 100 and measured by the current sensor 33 and the voltage measured by the voltage sensor 32 are maximized at different operating conditions, such as different or varying lighting conditions.

In one embodiment, solar cell 10 does not initially generate power for supplying an electric field 250, such as at night or in thick clouds. As the solar cell panels 10 are illuminated (eg, in the morning), voltage and current are generated by the solar cell panels 10, and the terminals 32a begin to supply current and voltage to the control circuit 35. The control circuit 35 includes a low voltage logic power supply (not shown) to drive the control logic in the control circuit 35. The control circuit 35 also contains a power supply 50 for providing a high voltage power supply. Voltage source 50 has a variable output that can be adjusted by control circuit 35 and is responsible for supplying V _App to pin 38. The high output voltage V _App of control circuit 35 drives pin 38 and connects to switch 55. Pin 38 is used to supply voltage V _App via switch 55 on 10 solar panel. In this example, the control circuit 35 is configured not to supply any voltage V _App to the solar panel 10 until the solar panels 10 have generated enough power to activate both the low voltage logic power supply and the high voltage power supply.

In an alternative embodiment, the control circuit 35 may be configured to apply the electric field 250 and maximize the power output as the illumination increases and decreases during the day. The control circuit 35 may provide an electric field 250 and stabilize the output power of the solar panels 10 in accordance with any method described above, including the process 9000 shown in FIG. 9B.

Referring to FIG. 9B, process 9000 includes power initialization at step 900. Sufficient power must be present at the output of the solar panels 10 to activate both the low voltage logic power supply that drives the control logic in the control circuit 35 and the high voltage power supply required to supply the high voltage to terminal 38 and through switch 55. Alternatively, the control circuit 35 may be powered by an external source (not shown) - for example, a battery, capacitor, external AC power supply - which allows the low voltage logic power supply to operate and circuit 35 control to track the output of the solar panels 10 until the solar panels 10 generate enough power to ensure that the electric field 250 is supplied to the solar panels 10 with increasing power output. After the control circuit 35 is started, all parameters (for example, the applied high voltage V _App , the switching duration D and the switching frequency f) are initialized. In one embodiment, the applied high voltage V _{App is} set to zero, and the switching duration D and the switching frequency f are set to nominal values: D = To and f = f _o . All check indices: n, i, and j, are initialized to zero values. Then, in step 901, the control circuit 35 determines whether the voltage measured by the voltage sensor 32 is higher or lower than a predetermined minimum v _min and whether the current measured by the current sensor 33 is greater than a predetermined minimum, i _min . The combination of v _min and i _min was chosen such that the solar panels 10, defined as illuminated, generate a certain nominal percentage, for example 5%, of their average nominal power, which is sufficient generated power to power the power supply 50 in the control circuit 35 to increase the output power of the solar panels 10. If the control circuit 35 determines that both the measured current and the voltage are higher than the respective predetermined minima, then the circuit 35

- 11 038040 control is currently operational, and the process 9000 goes to block 903; otherwise, process 9000 transitions to an idle state at block 902 and returns to block 900.

In step 903, the control circuit 35 measures the current flowing to the inverter 31 with the current sensor 33, the voltage across the inverter 31 with the voltage sensor 32, and calculates the power (nominal, current x voltage) supplied through the inverter 31. The reference index n increases to n + 1. In step 904, the control circuit 35 compares V _App with V _max . V _max can be a predetermined value and is the maximum voltage that can be applied to the solar panel 10 without damaging either the solar panel 10 or the inverter 31. Depending on the type of solar panel 10, V _{max is} usually between 600 and 1000 V. If the value of V _{App is} less than V _max , then the process 9000 goes to block 906; otherwise, process 9000 waits at block 905.

In step 906, the control circuit 35 increases the applied high voltage V _App by nΔV and activates the switch 55. Activation of the switch 55 disconnects the solar panels 10 from the inverter 31 and connects the solar panels 10 to V _App from the control circuit 35 at the terminals 38. For this For example, the ΔV may be a fixed voltage drop of 25V, although larger or smaller voltage drops may be used. The voltage VApp applies an electric field 250 on the solar panel 10 in such a way that the strength of the electric field 250 is proportional to the applied voltage VApp. The duration of the connection of solar panels 10 with V _App in the control circuit 35 is chosen so as not to interrupt the operation of the inverter 31. For this example, the duty factor is chosen to be 5% (solar panels 10 with 5% of the time are connected to V _App in the control circuit 35 ) and the default switching time is nominally 1000 ns. Alternative switching times can be used if desired. The control circuit 35 again receives the measurement of the current flowing to the inverter 31 by the current sensor 33, obtains a voltage measurement on the inverter 31 by the voltage sensor 32, and recalculates the power transmitted through the inverter 31.

In step 908, the control circuit 35 compares the output of the solar panels 10 with the most recent measurement before VApp is supplied to the solar panel 10. If the power has increased, then the process 9000 returns to block 901 and repeats. The voltage supplied to terminal 38 is increased by ΔV, either as long as the applied high voltage V _App is greater than V _max , or until an increase in the applied high voltage V _App increases the output of the solar panels 10. V _{max is} defined here as the maximum voltage that can be applied to a solar panel without causing any harm. Depending on the type of solar panel 10, V _max is typically about 600 to 1000 V. In both cases, process 9000 waits in step 905. The duration of the idle state can be from a few seconds to several minutes.

After wait block 905, process 9000 continues to block 907. If the power measured through pins 32a and 33a has not changed, index n decreases (n = n-1), applied voltage V _App at pins 38 to solar panel (s) 10 decreases by ΔV and control circuit 35 activates switch 55. Process 9000 continues to block 909 where output power is measured by current sensor 33 and voltage sensor 32. If the output shows a drop, the process 9000 continues to block 910. If the output power has increased, the process 9000 returns to block 907 and the applied voltage VApp continues to decrease until the output of the solar panels 10 stops decreasing. Process 9000 continues to block 910. At block 910, control circuit 35 increases the duration when switch 55 is connected to solar panel 10 at terminal 38 in the first position discussed above. The time interval when the switch 55 is connected to the voltage source 50 is increased by the amount. The switch 55 is activated, and the output power of the solar panels 10 is again monitored by the current sensor 33 and the voltage sensor 34. Process 9000 proceeds to condition 912 to determine if the output of the solar panels 10 is increasing. If so, then the process 9000 goes to block 910 and the duration when the solar panels 10 are connected to the voltage source 50 is increased again. The switching duration will increase until the output power of the solar panels 10 reaches its maximum (or until it reaches a fixed limit of duration, for example 3-5 μs), whereby changes in the switching duration caused by the control circuit 35 are stopped. However, if in step 912 the control circuit 35 determines that an increase in the switching duration D results in a decrease in the output power measured by the current sensor 33 and the voltage sensor 32, the process 9000 proceeds to step 911, and the switching duration D decreases by repeating steps 911 and 913 until the output power of the solar panels 10 is maximized again. After the control circuit 35 determines that the switching duration has been optimized for the maximum output of the solar panels 10 by repeating steps 910 through 913, process 9000 continues to step 914.

In step 914, the control circuit 35 begins to increase the connection frequency f at which the switch 55 is connected to the control circuit 35. The frequency f at which the switch 55 is connected to the voltage source 50 is increased by jΔf from the original _{switching frequency f o} so that f = f _o + jAf. In step 914, a switch 55 is connected between terminal 38 and the solar panels 10 at the new frequency, f, and the output of the solar panels 10 is again monitored by the current sensor 33 and the voltage sensor 34. Process 9000 continues to block 916. If the output of solar panels 10 has increased, process 9000 continues to block 914 and the frequency at which solar panels 10 are coupled to voltage source 50 is increased again. The frequency of the connection will increase until the output power of the solar panels 10 reaches its maximum, or to the maximum frequency f _max , causing the process 9000 to continue to block 915. At block 914, the frequency at which the switch 55 is connected to the source 50 high voltage at pin 38 is now reduced by the amount jAf, and switch 55 is reactivated and the output of the solar panels 10 is monitored again by current sensor 33 and voltage sensor 32. At this point, the control circuit 35 decides whether decreasing the connection frequency increases the output power of the solar panels 10 in step 917. If so, the process 9000 returns to step 915. Alternatively, if the switching frequency reaches some minimum frequency f _min , the process 9000 proceeds to block 918 to wait.

In step 918, after the output power of the solar panels 10 is maximized, the control circuit 35 goes into a standby state for a period of time. The timeout period can be seconds or minutes. After waiting at block 918, the process 9000 continues to block 901 where the process 9000 again begins to vary the voltage, switch connection time and switching frequency from the previous optimized values to check if the solar panels 10 are still operating at their maximum output power levels. The supplied voltage 50 from the control circuit 35, the switching duration and the switching frequency are all varied during operation throughout the day to ensure that the solar panels 10 are operating at their maximum power output under the operating conditions of a particular day.

If in step 901 the voltage measured by the voltage sensor 32 falls below a predetermined minimum v _min and the current measured by the current sensor 33 falls below a predetermined minimum i _min , then the control circuit 35 will remove any voltage on the lines 38 and the control circuit 35 will proceed to step 902 to wait before returning to block 900 (in which the system reinitializes all parameters and indexes). Process 9000 will alternate steps 900-901-902-900 until both the voltage measured by voltage sensor 32 and current measured by current sensor 33 exceed v _min and i _min, respectively, causing process 9000 to transition from from step 901 to step 903.

Various finite machines can be implemented in the control circuit 35 to obtain similar results and are covered by this disclosure. However, the process 9000 described above preferably minimizes the applied voltage V _App to the lowest possible value so that the product of the current measured by the current sensor 33 and the voltage measured by the voltage sensor 32 is maximized. The applied voltage V _App fluctuates, that is, changes by small amounts both up and down - during operation during the day, in order to account for changes in the power of optical radiation p incident on the solar cell 100, solar panel 10 or multiple solar panels 10 during the day so that the maximum power output can always be maintained.

Most of the steps outlined above in the 9000 process are designed to address adiabatic changes in illumination that occur slowly over time intervals of several minutes or hours. In an alternative embodiment, if the luminance fluctuations occurred at a higher rate of change, the process 9000 may be configured to minimize high frequency fluctuations in the DC output power supplied to the inverter by attempting to keep the DC output power from changing at a too high rate of change, therefore improving the quality of the inverter.

In another example, referring to FIG. 10A, current sensor 33 and voltage sensor 32 are shown connected to the photovoltaic cell control system 300 shown in FIG. 6. As shown, the current sensor 33 is connected in series between the solar panel 10 and the inverter 31. The current sensor 33 can monitor the output current of the solar panel 10. Likewise, a voltage sensor 32 is connected in parallel to the solar panels 10 and an inverter 31 to monitor the output voltage of the solar panel 10.

The control circuit 36 is connected to both the current sensor 33 via the control terminals 33a and to the voltage sensor 32 via the control terminals 32a. The current sensor 33 can be a built-in or inductive metering unit and measures the output current of the solar panels 10. Similarly, the voltage sensor 32 is used to measure the output voltage of the solar panels 10. The product of the current measured by the current sensor 33 and the voltage measured by the voltage sensor 32 allows the output power supplied from the solar panels 10 to the inverter 31 to be calculated. In some embodiments, the voltage sensor 32 may

- 13 038040 also serve as a power source for the control circuit 36 and only functions as long as the solar panels 10 are illuminated and provide sufficient power to activate the control circuit 36. A control circuit 36 is further connected to a voltage pulse generating device 60 to control the amplitude of the voltage pulse V _App , the _{pulse width D P} and the pulse repetition rate f discussed with reference to FIG. 6. The _{pulse duration D P} , the pulse repetition rate f and the voltage V _{App of the} pulse applied to the solar panel 10 can be controlled and adjusted so that both the current generated in the solar panel 10 and measured by the current sensor 33 and the voltage measured by the voltage sensor 32 has been maximized under different operating conditions, such as different or varying lighting conditions.

In one embodiment, solar cell 10 does not initially generate power for supplying an electric field 250, such as at night or in thick clouds. As the solar panels are illuminated (for example, in the morning hours), voltage and current are generated by the solar panels 10 and the terminals 32a begin to supply current and voltage to the control circuit 36. The control circuit 36 includes a low voltage logic power supply (not shown) to drive the control logic in the control circuit 36. The pulse generating circuit 60 includes both a low voltage and a high voltage power supply (not shown). The high voltage power supply in the voltage pulse generating device 60 has a variable output that can be controlled by the control circuit 36 and is responsible for supplying V _App to the solar panel 10. In this example, the control circuit 36 is configured not to supply any voltage to the solar panel 10 until sufficient power has been generated by the solar panels 10 to activate both the low voltage logic power supply and the high voltage power supply in the device. 60 to generate pulses. In an alternative embodiment, the control circuit 36 is configured to control the electric field 250 and maximize the power output as the illumination increases and decreases during the day. The control circuit 36 may control the electric field 250 supplied by the voltage pulse generating device 60 and stabilize the output power of the solar panels 10 in accordance with any method described above, including the process 10000 shown in FIG. 10B.

Referring to FIG. 10B, process 10000 includes initializing power at step 1000. Sufficient power must be present at the output of the solar panels 10 to activate both the low voltage logic power supply that drives the control logic in the control circuit 36 and the low and high voltage power supplies in the device 60 to generate voltage pulses. Alternatively, the control circuit 36 may be powered by an external source (not shown) such as a battery, a large capacitor, an external AC power supply that allows the low voltage logic power supply to operate, and the control circuit 36 monitors the output of the solar panels 10 to until they have enough power to ensure the supply of an electric field 250 to the solar panel 10 with increasing power output. After the control circuit 36 is started, all parameters are initialized (eg, applied high voltage V _App , pulse duration D _P, and pulse repetition rate f). In one embodiment, the applied high voltage V _{App is} set to zero and the _{pulse width D P} and the pulse repetition rate f are set to nominal values: Op = _to and f = f _o . All check indices - n, i, and j - are initialized to zero values.

Then, in step 1001, the control circuit 36 determines whether the voltage measured by the voltage sensor 32 is higher or lower than a predetermined minimum v _min , and whether the current measured by the current sensor 33 is greater than a predetermined minimum, i _min . The combinations of v _min and i _min were chosen so that solar panels 10, defined as illuminated, generate some nominal percentage, for example 5%, of their average nominal power, which is sufficient generated power to power the high voltage power supply to increase the output the power of the panels is 10 solar cells. If the control circuit 36 determines that both the measured current and the voltage are above the respective predetermined minima, then the current process 10000 proceeds to step 1003; if not, then the process 10000 goes to the standby state 1002 and returns to step 1000. In step 1003, the control circuit 36 measures the current flowing to the inverter 31 using the current sensor 33, the voltage across the inverter 31 using the voltage sensor 32, and calculates the power, transmitted through the inverter 31 (nominally IxV). The check index n is increased to n + 1. At block 1004, process 10000 compares V _App to V _max . V _max is a predetermined value and is the maximum voltage that can be applied to the panels without damaging either the panel 10 or the inverter 31. If V _{App is} less than V _max , then the process 10000 goes to step 1006; otherwise, process 10000 waits at block 1005.

In step 1006, the control circuit 36 provides a signal to the device 60 for generating pulses on

- 14 038040 voltage to increase the applied high voltage V _App by the value nAV and sends a signal to the device 60 for generating voltage pulses to apply a voltage pulse to the solar panel 10. For this example, ΔV may be a fixed voltage drop of 25V, although larger or smaller voltage drops could be used. The voltage V _App applies an electric field 250 across the solar panel 10, and the strength of the electric field 250 is proportional to the applied voltage V _App . For this example, the pulse width D _P is chosen to be 1000 ns and the pulse repetition rate is chosen to be 20 µs. Other pulse widths and pulse repetition rates can also be selected. The control circuit 36 again receives the measurement of the current flowing to the inverter 31 by the current sensor 33, obtains a voltage measurement on the inverter 31 by the voltage sensor 32, and recalculates the power transmitted through the inverter 31.

In step 1008, the control circuit 36 compares the output of the solar panels 10 with the most recent measurement before VApp is applied to the solar panel 10. If the power has increased, the process 10000 returns to step 1001 and repeats. The applied voltage V _{App is} increased by ΔV until either the applied high voltage V _App is greater than V _max , or an increase in the applied high voltage V _App increases the output power of the solar panels 10. V _{max is} again defined here as the maximum voltage that can be applied to the solar panel 10 without causing any harm, and depending on the type of solar panel, it is generally between about 600 and 1000 V. In both cases process 10000 waits at block 1005. The duration of the wait state can range from a few seconds to several minutes. After wait block 1005, process 10000 continues to block 1007.

If the power measured through terminals 32a and 33a has not changed, the index n decreases (n = n-1), the applied voltage pulse V _App decreases by the amount ΔV, and the control circuit 36 activates the device 60 to generate the pulses. Process 10000 continues to block 1009 where the output power is measured by a current sensor 33 and a voltage sensor 32. If the output shows a drop, the process 10000 continues to 1010. If the output is increased, the process 10000 returns to 1007 and the applied voltage VApp continues to decrease until the output of the solar panels 10 stops decreasing. Process 10000 goes to block 1010.

At 1010, the control circuit 36 begins to increase the voltage pulse width _{D P.} The voltage pulse duration D _P is increased by an amount. The voltage pulse generator 60 is activated and the output of the solar panels 10 is monitored again by the current sensor 33 and the voltage sensor 34. Process 10000 transitions to state 1012 to determine if the output of the solar panels 10 is increasing. If so, then the process 10000 goes to block 1010, and the duration D _P of the voltage pulse 71 is increased again. The pulse duration D _P will increase until the output power of the solar panels 10 reaches a maximum or until it reaches a fixed duration limit, for example, until a pulse width of 5 μs is reached, resulting in changes in the switching duration due to the control circuit 36 , stop. However, if it is determined in step 1012 that increasing the pulse width results in a decrease in the output power measured by the current sensor 33 and the voltage sensor 32, the process 10000 proceeds to step 1011. The pulse width is decreased by repeating steps 1011 and 1013 until the output power of the solar panels 10 will not increase to the maximum again. After the control circuit 36 determines that the pulse width has been optimized for the maximum output power of the solar panels 10, proceeding from step 1010 to step 1013, the process proceeds to step 1014.

In step 1014, the control circuit 36 increases the frequency of the voltage pulses. The voltage pulse frequency increases by jAf from the initial switching frequency fo, so that f = f _o + jΔf. In step 1014, voltage pulses are applied by the device 60 to generate voltage pulses on the solar panel 10 at a new frequency f, and the output of the solar panels 10 is again monitored by the current sensor 33 and the voltage sensor 34. Process 10000 then continues to block 1016.

If the output power of the solar panels 10 is increased, the process 10000 goes back to block 1014, and the frequency at which the voltage pulses are applied to the solar panel 10 increases again. The increase in the frequency of the voltage pulses will increase until the output power of the solar panels 10 reaches the maximum, or to the maximum frequency f _max , whereby the process 10000 continues to step 1015. At step 1014, the frequency of the voltage pulses is now reduced by the amount j∆f. and the switch of the voltage pulse generating device 60 is activated again, and the output of the solar panels 10 is again monitored by the current sensor 33 and the voltage sensor 32. At this point, the control circuit 36 determines whether decreasing the voltage pulse frequency increases the output of the solar panels 10 in step 1017. If so, the process 10000 returns to step 1015. Alternatively, if the switching frequency reaches some minimum frequency f _min , process 10000 goes to block 1018, which is a pending state.

At 1018, after the output power of the solar panels 10 has been maximized, the process 10000 goes into a standby state for a period of time. The timeout period can be seconds or minutes. After waiting at block 1018, the process 10000 continues to block 1001, where the control circuit 36 again begins to vary the pulse voltage, pulse width and pulse repetition rate from the previous optimized values to check if the solar panels 10 are still operating at their maximum output levels. power. Pulse amplitude V _App , pulse width and pulse repetition rate all change during operation throughout the day to ensure that the solar panels 10 are operating at their maximum power output under operating conditions on a particular day.

If in step 1001 the voltage measured by the voltage sensor 32 falls below a predetermined minimum v _min and the current measured by the current sensor 33 falls below a predetermined minimum i _min , then the control circuit 36 will stop the voltage pulse generating device 60 and the process 10000 will go to step 1002, an idle state, and then at step 1000, where the system reinitializes all parameters and indexes. The process 10000 will go from step 1000 to 1001, to 1002, to 1000 until the voltage measured by the voltage sensor 32 and the current measured by the current sensor 33 are greater than v _min and i _min, respectively, causing the process 10000 to go from block 1001 to block 1003. Various end machines may be implemented in control circuitry 36 to obtain similar results and are covered by this disclosure. However, the process 10000 described above preferably minimizes the applied _{voltage pulse V App} to the lowest possible value so that the product of the current measured by the current sensor 33 and the voltage measured by the voltage sensor 32 is maximized. The applied voltage pulse V _App fluctuates - that is, changes by small amounts both up and down - during operation during the day to account for changes in the power of optical radiation p falling on a solar cell 100, solar panel 10 or multiple solar panels 10 elements during the day so that the maximum output power can always be maintained.

The steps outlined in process 10,000 can address adiabatic changes in illumination that occur slowly over time intervals of several minutes or hours. In an alternative embodiment, if the luminance fluctuations occurred at a higher rate of change, process 10000 may be configured to minimize high frequency fluctuations in the DC output power supplied to the inverter by attempting to keep the DC output from changing at a too high rate of change, hence improving the quality of the inverter.

The described embodiments are susceptible of various modifications and alternative forms, and their specific examples have been shown by way of example in the drawings and are described in detail in this application. However, it should be understood that the described embodiments should not be limited to the specific forms or the methods disclosed, but rather, the present invention covers all modifications, equivalents and alternatives.

Claims (53)

CLAIM 1. A system for increasing the efficiency of a photovoltaic device, comprising a voltage supply means for switching between supplying a voltage signal to the photovoltaic device during the first predetermined time interval and stopping the voltage signal supply to the photovoltaic device during a second predetermined time interval, and the voltage signal includes itself at least one positive-amplitude voltage pulse to generate an electric field on the photovoltaic device to increase the output current generated by the photovoltaic device and / or the output power generated by the photovoltaic device. 2. The system of claim 1, wherein said voltage supply means comprises a constant voltage source for supplying a voltage signal as a constant voltage signal and switching means for connecting said DC voltage supply means to the photovoltaic device. 3. The system of claim 2, wherein said constant voltage supply means is configured to supply a constant voltage signal with a potential of 100 to 500 V, inclusive. 4. The system according to claim 2 or 3, wherein said switching means is configured to supply a constant voltage signal to the photovoltaic device during a first predetermined time interval and to stop supplying a constant voltage signal to the photovoltaic device. - 16 038040 food during the second set time interval. 5. A system according to any one of claims 2 to 4, wherein said switching means is configured to switch between closing the current path between said DC voltage supply means and the photovoltaic device during a first predetermined time interval and opening said current path during a second predetermined interval time. 6. The system of claim 5, wherein said switching means is configured to supply a constant voltage signal to the photovoltaic device through a current path for a first predetermined time interval. 7. A system according to any one of claims 2 to 6, wherein said switching means comprises at least one single pole, double throw switch, at least one switching transistor, or a combination thereof. 8. A system as claimed in any one of claims 2-7, wherein the photovoltaic device is configured to provide increased output current and / or increased output power to the load. 9. The system of claim 8, wherein said switching means is capable of being connected to a load, wherein the photovoltaic device is configured to provide increased output current and / or increased output power to the load for a first predetermined time and a second predetermined time. 10. The system according to claim 8 or 9, wherein said switching means comprises a two-position switching means with a first terminal for connection to said DC voltage supply means, a second terminal for connecting to a load and a common terminal for connecting to a photovoltaic device, configured to set a first current path between said DC voltage supply means and the photovoltaic device for a first predetermined time; and establishing a second current path between the photovoltaic device and a load for a second predetermined time. 11. The system of claim 10, wherein said switching means is configured to provide increased output current and / or increased output power to the load for a first predetermined time. 12. A system according to any one of claims 1 to 11, in which said voltage supply means comprises a controlled voltage supply means for supplying a voltage signal as a controlled voltage signal, a periodic voltage supply means for supplying a voltage signal as a periodic voltage signal, a controlled voltage supply means voltage to supply a voltage signal as a time-varying voltage signal, or a combination of both. 13. A system according to any one of claims 1 to 12, wherein said voltage supply means is configured, during a first predetermined time interval, to supply a voltage signal to a plurality of photovoltaic devices generating an electric field on said plurality of photovoltaic devices to increase the output current generated by the photovoltaic device. device, and / or the output power generated by the specified plurality of photovoltaic devices. 14. The system of claim 13, wherein the plurality of photovoltaic devices are arranged in a series configuration, a parallel configuration, or a combination thereof. 15. A system as claimed in any one of claims 1-14, wherein said voltage supply means is configured to provide a voltage signal as a periodic voltage signal for generating an electric field on the photovoltaic device. 16. A system according to any one of claims 1-15, in which the voltage signal has an amplitude in the range from 100 to 500 V, a frequency in the range from 20 to 200 kHz, a period in the range from 5 to 50 μs, a nominal duty cycle in the range from 0.1 to 10%, or a combination thereof. 17. The system according to any one of claims 1-16, further comprising control means for adjusting the first duration of the first predetermined time interval, the second duration of the second predetermined time interval, the duty cycle of the first and second predetermined time intervals, the first pulse repetition rate of the first predetermined time interval, the second pulse repetition rate of the second predetermined time interval or their combination. 18. The system according to claim 17, in which said control means is configured to maintain the first duration in the first range of duration from 10 to 2000 ns, the second duration in the second range of duration from 10 to 2000 ns, the duty cycle of the voltage pulse in the range from 0, 1 to 10% or combinations thereof. 19. The system of claim 17 or 18, wherein said control means is at least partially integrated into the voltage supply means. 20. The system according to any one of claims 1-19, further comprising control means for adjusting the frequency of the voltage signal supplied to the photovoltaic device, the magnitude of the voltage signal supplied to the photovoltaic device, the period of the voltage signal supplied to the photovoltaic device, the pulse repetition rate of the voltage signal applied to the photovoltaic device, the duty cycle of the voltage signal applied to the photo- - 17 038040 electrical device, the duration of the voltage signal applied to the photovoltaic device, or combinations thereof. 21. The system according to claim 20, in which said control means is configured to maintain a frequency in the range from 20 to 200 kHz, a value in the range from 100 to 500 V, a period in the range from 5 to 50 μs, a duty factor in the range from 0 , 1 to 10%, duration in the range from 10 to 2000 ns, or their combination. 22. The system of claim 20 or 21, wherein said control means is configured to adjust frequency, magnitude, period, repetition rate, duty cycle, duration, or a combination thereof at least in part based on the output current of the photovoltaic device and / or the output voltage of the photovoltaic device. 23. A system according to any one of claims 20-22, further comprising measuring means for measuring the output current of the photovoltaic device and / or the output voltage of the photovoltaic device, said control means being configured to adjust the frequency, magnitude, period, repetition rate, duty cycle, duration or a combination thereof based at least in part on the measured output current and / or the measured output voltage. 24. The system of claim 23, wherein said measuring means includes a current sensor configured to measure an output current and connected in series between the photovoltaic device and a load supplied by the photovoltaic device, and / or a voltage sensor configured to measure the output voltage and connected in parallel to the photovoltaic device. 25. A system according to any one of claims 20-24, wherein said control means is configured to control the electric field, output current, output power, or a combination thereof by adjusting the voltage signal. 26. The system of claim 25, wherein said control means is configured to maximize the output current of the photovoltaic device and / or the output power of the photovoltaic device. 27. A system according to any one of claims 20 to 26, wherein said control means is at least partially integrated into said voltage supply means. 28. A system according to any one of claims 1 to 27, wherein the photovoltaic device is configured to provide increased output current and / or increased output power to the load. 29. The system of claim 28, wherein the load is configured to convert the increased output current and / or increased output power generated by the photovoltaic device into AC or AC power. 30. The system of claim 29, wherein the load comprises an inverter. 31. The system of claim 29 or 30, wherein the load is electrically isolated from the photovoltaic device in the RF region. 32. The system of any one of claims 28 to 31, wherein the load is electrically isolated from the photovoltaic device via a capacitor, inductor, battery, or a combination thereof. 33. A system according to any one of claims 28 to 32, further comprising energy storage means for reducing the voltage drop across the load during a first predetermined time interval. 34. The system of claim 33, wherein said energy storage means comprises a capacitor, an inductor, a storage battery, or a combination thereof. 35. The system of claim 33 or 34, wherein said energy storage means is configured to store an output current and / or output power generated by the photovoltaic device in a second mode of said switching means. 36. The system of claim 35, wherein said energy storage means is configured to control the load through the stored output power and / or the stored output current for a first predetermined time interval. 37. The system of claim 36, further comprising isolation means for electrically isolating the load from the photovoltaic device in the RF region while controlling the load with said energy storage means. 38. The system of claim 37, wherein said isolation means comprises a choke, capacitor, inductor, battery, or a combination thereof. 39. The system according to any one of claims 1 to 38, in which the increase in the output current and / or output power generated by the photovoltaic device is based on the intensity of light incident on the photovoltaic device, the thickness of the photovoltaic device, the duration of the voltage signal during the first predetermined time interval , the frequency of the voltage signal. 40. A system according to any one of claims 1 to 39, wherein said voltage supply means is connected to one or more existing electrodes of the photovoltaic device. 41. A system according to any one of claims 1 to 40, in which said voltage supply means is configured to supply a voltage signal to the photovoltaic device without structural - 18 038040 changes to the photovoltaic device. 42. A system according to any one of claims 1 to 41, wherein the photovoltaic device comprises a solar cell, a solar cell array, a solar cell panel, a solar cell array, or a combination thereof. 43. A system as claimed in any one of claims 1 to 42, wherein generating an electric field is capable of increasing the output current and / or output power of the photovoltaic device by up to 50% in low light conditions. 44. A system according to any one of claims 1 to 42, wherein the generation of the electric field is capable of increasing the output current and / or the output power generated by the photovoltaic device by more than 50% in low light conditions. 45. A system according to any one of claims 1 to 44, wherein the generation of the electric field is capable of increasing the output current and / or the output power generated by the photovoltaic device by up to 20% under high light intensity conditions. 46. A system as claimed in any one of claims 1 to 45, wherein the generation of the electric field is capable of increasing the output current and / or the output power of the photovoltaic device by 20 to 50%. 47. A system according to any one of claims 1 to 45, wherein the generation of the electric field is capable of increasing the output current and / or the output power generated by the photovoltaic device by more than 50%. 48. A method for increasing the efficiency of a photovoltaic device, comprising the steps of providing a voltage supply means; and connecting the voltage supply means to the photovoltaic device, said voltage supply means being configured to switch between supplying a voltage signal to the photovoltaic device during the first predetermined time interval and stopping the voltage signal supply to the photovoltaic device during the second predetermined time interval, the voltage signal turning on into at least one positive amplitude voltage pulse to generate an electric field on the photovoltaic device to increase the output current generated by the photovoltaic device and / or the output power generated by the photovoltaic device. 49. The method of claim 48, wherein the voltage supply means is configured to be connected to the load to provide increased output current and / or increased output power to the load during a second predetermined time interval. 50. The method of claim 48, wherein the voltage supply means is configured to be connected to the load to provide increased output current and / or increased output power to the load during a first predetermined time interval and during a second predetermined time interval. 51. A method for increasing the efficiency of a photovoltaic device, comprising the steps of connecting the photovoltaic device to a voltage supply means configured to switch between supplying a voltage signal to the photovoltaic device during a first predetermined time interval and stopping the supply of a voltage signal to the photovoltaic device during a second predetermined time interval, wherein the voltage signal includes at least one voltage pulse with a positive amplitude for generating an electric field on the photovoltaic device to increase the output current generated by the photovoltaic device and / or the output power generated by the photovoltaic device. 52. The method of claim 51, further comprising the step of connecting the photovoltaic device to the load, the photovoltaic device being configured to provide increased output current and / or increased output power to the load during a second predetermined time interval. 53. The method according to claim 51, further comprising the step of connecting the photovoltaic device to the load, wherein the photovoltaic device is configured to provide increased output current and / or increased output power supplied to the load during a first predetermined time interval and for the second specified time interval.