Abstract:
A method for testing a photovoltaic panel connected to an electronic module. The electronic module includes an input attached to the photovoltaic panel and a power output. The method activates a bypass to the electronic module. The bypass provides a low impedance path between the input and the output of the electronic module. A current is injected into the electronic module thereby compensating for the presence of the electronic module during the testing. The current may be previously determined by measuring a circuit parameter of the electronic module. The circuit parameter may be impedance, inductance, resistance or capacitance.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a continuation of U.S. patent application Ser. No. 13/015,219, filed on Jan. 27, 2011, which is a continuation-in-part application of U.S. patent application Ser. No. 12/314,115 filed on Dec. 4, 2008, (now issued as U.S. Pat. No. 8,324,921) the disclosures of which are included herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to production testing of photovoltaic panels, and more specifically to testing of photovoltaic panels which include integrated circuitry. 
       DESCRIPTION OF RELATED ART 
       [0003]    Current voltage (IV) characteristics of a conventional photovoltaic panel are measured using a flash tester. The flash tester measures electrical current characteristics of a photovoltaic panel during a single flash of light of duration typically within one millisecond emitted by the flash lamp. The measurement procedure is based on known properties of a reference photovoltaic panel which has been independently calibrated in an external laboratory. The external laboratory has determined accurately the short circuit current corresponding to standard test conditions (STC) using an AM1.5G spectrum. AM1.5G approximates a standard spectrum of sunlight at the Earth&#39;s surface at sea level at high noon in a clear sky as 1000 W/m2. “AM” stands for “air mass” radiation. The ‘G’ stands for “global” and includes both direct and diffuse radiation. The number “1.5” indicates that the length of the path of light through the atmosphere is 1.5 times that of the shorter path when the sun is directly overhead. During flash testing homogeneity of irradiance over the photovoltaic panel is obtained by a 6-meter distance between the flash lamp and the photovoltaic panel. 
         [0004]    Reference is now made to  FIG. 2  which illustrates a conventional flash testing system  7 . The flash testing system  7  includes a photovoltaic panel  10 , flash tester  17  and a flash lamp  16 , placed inside a closed lightproof cabin  19  which is painted black inside. Alternatively, black curtains minimize the intensity of reflections towards photovoltaic panel  10  from the interior surfaces of the cabin. The homogeneity of irradiance over area of photovoltaic panel  10  is measured by placing an irradiance sensor in various positions of the measurement plane. During the flash testing procedure, a flash tester  17  is connected to the output of photovoltaic panel  10 . The measurement procedure starts with a flash test of a reference photovoltaic panel. The short circuit current is measured during an irradiance corresponding to AM1.5G. The reference photovoltaic panel is then exchanged for the test photovoltaic panel. During a subsequent flash, the irradiance sensor triggers a current-voltage (IV) measurement procedure at the same irradiance as during the measurement of the reference photovoltaic panel. 
         [0005]    Conventional photovoltaic panels are typically connected together in series to form strings and the strings are optionally connected in parallel. The combined outputs of the connected photovoltaic panels are typically input to an inverter which converts the generated direct current voltage to alternating current of the grid. Recently, photovoltaic panels have been designed or proposed with integrated circuitry. 
         [0006]    Reference is now made to  FIG. 1  which illustrates schematically a photovoltaic system  14  with a circuit or electronic module  12  integrated with a photovoltaic panel  10 . The term “electronic module” as used herein refers to electronic circuitry integrated at the output of the photovoltaic panel. The “electronic module” itself may be of the prior art or not of the prior art. A representative reference (Cascade DC-DC Converter Connection of Photovoltaic Modules, G. R. Walker and P. C. Sernia,  Power Electronics Specialists Conference,  2002. (PESC02), Vol. 1 IEEE, Cairns, Australia, pp. 24-29) proposes use of DC-DC converters integrated with the photovoltaic panels. The DC-DC converter integrated with the photovoltaic panel is an example of an “electronic module”. Other examples of “electronic modules” include, but are not limited to, DC-AC inverters and other power conditioning electronics, as well as sensing and monitoring electronics. 
         [0007]    Another reference of the present inventors which describes an example of photovoltaic system  14  including photovoltaic panel  10  integrated with electronic module  12  is US20080143188, entitled “Distributed Power Harvesting Systems Using DC Power Sources”. 
         [0008]    The “electronic module” herein may have electrical functionality, for instance for improving the electrical conversion efficiency of photovoltaic system  14 . Alternatively, “electronic module” as used herein may have another functionality unrelated to electrical performance. For instance in a co-pending patent application entitled, “Theft detection and Prevention in a Power Generation System”, the function of electronic module  12  is to protect photovoltaic system  12  from theft. 
         [0009]    Since a standard flash test cannot typically be performed on panel  10  after integration with electronic module  12 , for instance because the presence of module  12  affects the results of the standard test, it would be advantageous to have a system and method for flash testing of photovoltaic system 
         [0010]    The term “photovoltaic panel” as used herein includes any of: one or more solar cells, cells of multiple semiconductor junctions, solar cells connected in different ways (e.g. serial, parallel, serial/parallel), of thin film and/or bulk material, and/or of different materials. 
       BRIEF SUMMARY 
       [0011]    According to aspects of the present invention there is provided a method for testing a photovoltaic panel connected to an electronic module. The electronic module includes an input attached to the photovoltaic panel and a power output. The method activates a bypass to the electronic module. The bypass provides a low impedance path between the input and the output of the electronic module. A current is injected into the electronic module thereby compensating for the presence of the electronic module during the testing. The current may be previously determined by measuring a circuit parameter of the electronic module. The circuit parameter may be impedance, inductance, resistance or capacitance. The electronic module is preferably permanently attached to the photovoltaic panel. The activation of the bypass may be by externally applying either an electromagnetic field or a magnetic field. The electronic module may be either a DC to DC converter, DC to AC converter or maximum power point tracking converter. The electronic module performs maximum power point tracking to maximize power at either an input or an output of the electronic module. The bypass may include a reed switch, a reed relay switch, a solid state switch or a fuse. The bypass may include a fuse  30  which has a power supply connected direct across the fuse where a current flow from the power supply, de-activates the bypass by blowing the fuse. The bypass may typically include a solid state switch. The bypass may further include a fuse and a parallel connected switch which is disposed between and connected in parallel with the photovoltaic panel and the electronic module. A power supply unit is typically connected across the outputs of the electronic module and closing the switch, provides a low impedance path across the fuse, thereby blowing the fuse. The parallel-connected switch may be a silicon controlled rectifier, reed switch, solid state switch or reed relay. Blowing the fuse typically de-activates the bypass of the electronic module. De-activating the bypass is preferably performed by communicating with the electronic module. 
         [0012]    According to aspects of the present invention there is provided a device for testing a photovoltaic panel system including a photovoltaic panel connected to an electronic module. The electronic module includes at least one input attached to the photovoltaic panel and at least one power output. The device includes a bypass operatively attached to the electronic module. The bypass provides a low impedance path between the at least one power output and the at least one input of the electronic module. A current injector may be operatively attached to the electronic module. A circuit parameter analyzer is operatively attached to the electronic module. The circuit parameter analyzer is adapted to measure a circuit parameter of the electronic module. A processor may be operatively attached to the circuit parameter analyzer. The processor is preferably configured to program the programmable current injector based on the circuit parameter. The current may be determined by measuring a circuit parameter of the electronic module. The circuit parameter may be impedance, inductance, resistance or capacitance. 
         [0013]    The bypass may further include a bypass component which has at least one switch and at least one fuse. The bypass component typically connects the at least one power output and the at least one input of the electronic module. The at least one switch may be a magnetically activated reed switch, an electro-magnetically activated reed relay switch or a solid state switch. The electronic module typically performs maximum power point tracking. The electronic module may perform either: DC to DC conversion or DC to AC inversion. 
         [0014]    According to yet another aspect of the present invention there is provided a method for a device used whilst testing a photovoltaic panel system. The photovoltaic panel system includes a photovoltaic panel connected to an electronic module. The electronic module includes at least one input attached to the photovoltaic panel and at least one power output. The device typically includes a current injector operatively attached to the least one power output and to a test module; a circuit parameter analyzer operatively attached to the electronic module and a processor operatively attached to the circuit parameter analyzer. The method typically attaches a bypass to the electronic module. The bypass preferably provides a low impedance path between the at least one power output and the at least one input of the electronic module. Prior to testing the panel a circuit parameter of the least one power output is measured, followed by the current injector being programmed with a parameter based on the measuring. Injecting current and triggering the test module is typically performed simultaneously, thereby compensating for the presence of the electronic module during the triggering. 
         [0015]    The foregoing and/or other aspects will become apparent from the following detailed description when considered in conjunction with the accompanying drawing figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The invention is herein described, by way of example only, with reference to the accompanying drawings, wherein: 
           [0017]      FIG. 1  illustrates an electrical power generation system including a photovoltaic panel and electronic module. 
           [0018]      FIG. 2  illustrates a flash test module of the prior art. 
           [0019]      FIG. 3  illustrates a general equivalent circuit, representing the electronic module shown in  FIGS. 1 and 2  with a bypass applied, according to a feature of the present invention. 
           [0020]      FIG. 4  shows a flow chart of a method to flash test a photovoltaic panel according to an embodiment of the present invention. 
           [0021]      FIG. 5  is an activated bypass circuit, according to an embodiment of the present invention, of an electronic module connected to a photovoltaic panel and test module. 
           [0022]      FIG. 6  is a de-activated bypass circuit, according to an embodiment of the present invention of an electronic module connected to a photovoltaic panel. 
           [0023]      FIG. 7  is an activated bypass circuit, according to another embodiment of the present invention, of an electronic module connected to a photovoltaic panel and test module. 
           [0024]      FIG. 8  is a de-activated bypass circuit, according to another embodiment of the present invention of an electronic module connected to a photovoltaic panel. 
           [0025]      FIG. 8   a  is a de-activated bypass circuit using a fuse and power supply, according to another embodiment of the present invention of an electronic module connected to a photovoltaic panel. 
           [0026]      FIG. 8   b  is a de-activated bypass circuit using a fuse, power supply and silicone controlled rectifier (SCR), according to yet another embodiment of the present invention of an electronic module connected to a photovoltaic panel. 
           [0027]      FIG. 9  is an activated bypass circuit, according to yet another embodiment of the present invention, of an electronic module connected to a photovoltaic panel and test module. 
           [0028]      FIG. 10  is a de-activated bypass circuit, according to yet another embodiment of the present invention of an electronic module connected to a photovoltaic panel. 
           [0029]      FIG. 11  illustrates yet another way in which to de-activate bypass once a flash test has been performed according to a feature of the present invention. 
           [0030]      FIG. 12   a  shows a module connected to a compensation unit according to a feature of the present invention. 
           [0031]      FIG. 12   b  shows further details of the compensation unit shown in  FIG. 12   a , according to a feature of the present invention. 
           [0032]      FIG. 12   c  shows a simulation circuit, according to a feature of the present invention. 
           [0033]      FIG. 12   d  shows simulation results of a test circuit shown in  FIG. 12   c , according to a feature of the present invention. 
           [0034]      FIG. 12   e  shows another simulation circuit, according to a feature of the present invention. 
           [0035]      FIG. 12   f  shows the simulation results a test circuit shown in  FIG. 12   e , according to a feature of the present invention. 
           [0036]      FIG. 12   g  shows a simulation circuit, according to a feature of the present invention. 
           [0037]      FIG. 12   h  shows the compensated simulation results of a test circuit, according to a feature of the present invention. 
           [0038]      FIG. 12   i  which shows a method, according to a feature of the present invention. 
           [0039]      FIG. 12   j  which shows a method, according to a feature of the present invention. 
       
    
    
       [0040]    The foregoing and/or other aspects will become apparent from the following detailed description when considered in conjunction with the accompanying drawing figures. 
       DETAILED DESCRIPTION 
       [0041]    Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings; wherein like reference numerals refer to the like elements throughout. The embodiments are described below to explain the present invention by referring to the figures. 
         [0042]    Reference is now made back to  FIG. 1  which illustrates electrical power generation system  14 , including photovoltaic panel  10  connected to electronic module  12 . In some embodiments of the present invention, electronic module  12  is “permanently attached” to photovoltaic panel  10 . In other embodiments of the present invention, electronic module is integrated with photovoltaic panel  10  but is not “permanently attached” to photovoltaic panel  10 . The term “permanently attached” as used herein refers to a method or device for attachment such that physical removal or attempt thereof, e.g. of electronic module  12  from photovoltaic panel  10 , would result in damage, e.g. to electronic module  12  and/or panel  10 . Any mechanism known in the art for “permanently attaching” may be applied indifferent embodiments of the present invention. When electronic module  12  is permanently attached to the photovoltaic panel  10 , the operation of photovoltaic panel  10  ceases or connections thereof are broken on attempting to remove electronic module  12  from photovoltaic panel  10 . One such mechanism for permanently attaching uses a thermoset adhesive, e.g. epoxy based resin, and hardener. 
         [0043]    Referring to  FIG. 3 , an example of electronic module  12  is illustrated in more detail. Electronic module  12  connects photovoltaic panel  10  and test module  20 . Impedance Z 1  is the series equivalent impedance of electronic module  12 . Impedance Z 2  is the equivalent input impedance of electronic module  12 . Impedance Z 3  is the equivalent output impedance of electronic module  12 . Bypass link  40  when applied between the output of photovoltaic panel  10  and the input of test module  20  eliminates the effects of series equivalent impedance Z 1  during a flash test. With bypass link  40  applied, impedances Z 2  and Z 3  are connected in parallel with resulting shunt impedance Z T  given in Eq. 1. 
         [0000]    
       
         
           
             
               
                 
                   
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         [0000]    Where impedances Z 2  and Z 3  are both high in value, ZT will have an insignificant effect upon a flash test of photovoltaic panel  10 . 
         [0044]    Reference is made to  FIGS. 4 ,  5  and  6  which illustrate embodiments of the present invention.  FIG. 4  illustrates a flowchart for a method for flash testing a photovoltaic panel  10  by bypassing an electronic module  12  according to embodiments of the present invention.  FIGS. 5 and 6  are corresponding system drawings according to embodiments of the present invention of electrical power generation system  14 .  FIG. 5  illustrates bypass  40  when bypass  40  is activated. With reference to  FIG. 5 , a single pole single throw (SPST) switch  50  activated by magnetic field of magnet  52  connects the output of photovoltaic panel  10  and the input of test module  20  to bypass electronic module  12  during a flash test of photovoltaic panel  10 . SPST switch  50  in an embodiment of the present invention is a reed switch (for example, Part no: HYR 2031-1, Aleph America Corporation NV USA) or a reed relay, or a solid state switch. Bypass  40  of electronic module  12  is activated (step  201 ) by applying a magnetic field  52  to SPST switch  50  causing SPST switch  50  to close as shown in  FIG. 5 . The flash test is performed (step  203 ) using flash test module  20 . After the flash test of photovoltaic panel  10 , bypass  40  of electronic module  12  is de-activated by the removal of magnetic field  52  to SPST switch  50  (step  205 ).  FIG. 6  illustrates photovoltaic panel  10  connected to the input of electronic module  12 , with SPST switch  50  bypass de-activated (step  205 ). 
         [0045]    Reference is made to  FIGS. 7 and 8  which illustrate another embodiment of the present invention.  FIG. 7  illustrates bypass  40 . With reference to  FIG. 7 , a fuse  50   a  connects the output of photovoltaic panel  10  and the input of test module  20  to bypass electronic module  12  during a flash test of photovoltaic panel  10 . Referring back to  FIG. 4 , bypass  40  of electronic module  12  is activated (step  201 ) by virtue of fuse  50   a  being in an un-blown state as shown in  FIG. 7  and SPST switch  5   b  being open circuit. SPST switch  5   b  in an embodiment of the present invention is a reed switch (for example, Part no: HYR 2031-1, Aleph America Corporation NV USA) or a reed relay, or a solid state switch. The flash test is performed (step  203 ) using flash test module  20 . After the flash test of photovoltaic panel  10 , bypass  40  of electronic module  12  is de-activated (step  205 ).  FIG. 8  shows bypass  40  being de-activated (step  205 ).  FIG. 8  shows photovoltaic panel  10  connected to the input of electronic module  12  and a power supply unit (PSU)  13  applied across the output of electronic module  12 . SPST switch  5   b  is in a closed position because of the application of magnetic field  52 . 
         [0046]    Reference now made to  FIG. 11  which illustrates yet another way in which to deactivate bypass  40  (step  205 ) once a flash test has been performed (step  203 ) according to a feature of the present invention. Photovoltaic panel  10  is connected to the input of buck boost converter  12   a . The output of buck boost converter  12   a  is connected to PSU  13 . During deactivation of bypass  40  (step  205 ), a power line communication superimposed on the output of buck boost converter  12   a  via PSU  13 , a wireless signal applied in the vicinity of buck boost converter  12   a , or based on some logic circuitry—i.e. a specific supply voltage applied by PSU  13  causes MOSFETS G C  and G A  to turn on. MOSFETS G C  and G A  turned on causes a short circuit current I SC  to flow from PSU  13  and through fuse  50   a . The short circuit I SC  current blows fuse  50   a  making fuse  50   a  open circuit and bypass  40  is de-activated (step  205 ). 
         [0047]    The closure of SPST switch  5   b  and application of PSU  13  applied across the output of electronic module  12 , causes a short circuit current I SC  to flow from PSU  13  through fuse  50   a  and SPST switch  5   b . The short circuit I SC  current blows fuse  50   a  making fuse  50   a  open circuit and the removal of magnetic field  52  de-activates bypass  40  (step  205 ). 
         [0048]    An alternative way of de-activating bypass  40  (step  205 ) is shown in  FIG. 8   a .  FIG. 8   a  shows photovoltaic panel  10  connected to the input of electronic module  12  and a power supply unit (PSU)  13  applied across fuse  50   a . The application of PSU  13  across fuse  50   a , causes a short circuit current I SC  to flow from PSU  13  and through fuse  50   a . The short circuit I SC  current blows fuse  50   a  making fuse  50   a  open circuit and bypass  40  is de-activated (step  205 ). 
         [0049]    Another way of de-activating bypass  40  (step  205 ) is shown in  FIG. 8   b .  FIG. 8   b  shows photovoltaic panel  10  connected to the input of electronic module  12  and a power supply unit (PSU)  13  applied across the output of electronic module  12 . The anode and cathode of a silicon controlled rectifier (SCR)  15  is connected in parallel across the output of photovoltaic panel  10  and the input of electronic module  12 . The gate of an SCR  15  is connected inside electronic module  12  in such a way that the application of PSU  13  across the output of electronic module  12  causes a gate signal to be applied to the gate of SCR. A gate pulse applied to SCR  15  switches SCR  15  on. Alternative ways to get a pulse to the gate of SCR  15  include, power line communication superimposed on the output of electronic module  12  via PSU  13 , a wireless signal applied in the vicinity of electronic module  12 , or based on some logic circuitry—i.e. a specific supply voltage applied by PSU  13  causes a gate signal to be applied to SCR  15 . A gate signal applied to SCR  15  and application of PSU  13  applied across the output of electronic module  12 , causes a short circuit current I SC  to flow from PSU  13  through fuse  50   a  and SCR  15 . The short circuit I SC  current blows fuse  50   a  making fuse  50   a  open circuit and bypass  40  is de-activated (step  205 ). 
         [0050]    Reference is now made to  FIGS. 4 ,  9  and  10  which illustrate another embodiment of the present invention of electrical power generation system  14 , particularly applicable in cases when the resulting shunt impedance Z T  is small enough to disrupt the results of the flash test, such as being less than 1 Mega Ohm in electronic module  12 . Referring back to  FIG. 4 ,  FIG. 4  illustrates a flowchart for a method for flash testing a photovoltaic panel  10  by bypassing an electronic module  12  according to embodiments of the present invention.  FIG. 4  includes step  201  of activating a bypass, step  203  performing the flash and de-activating the bypass, step  205 . 
         [0051]      FIG. 9  illustrates bypass  40  when bypass  40  is activated. With reference to  FIG. 9 , a single pole double throw (SPDT) switch  70 , SPST switch  72  and SPDT switch  74 , activated by magnetic field of magnet  52 , connects the output of photovoltaic panel  10  and the input of test module  20  to perform the function of bypassing electronic module  12  during a flash test of photovoltaic panel  10 . SPDT switches  70  and  74  in an embodiment of the present invention is a reed switch (for example, Part no: HYR-1555-form-C, Aleph America Corporation Reno, Nev. USA) or a reed relay, or a solid state switch. SPDT switches  70  and  74  when activated by magnetic field  52  provide open circuit impedance in place of shunt impedance Z T  when electronic module  12  is being bypassed during a flash test of photovoltaic panel  10 . The bypass  40  of electronic module  12  is activated (step  201 ) by applying a magnetic field  52  to SPST switch  72  and SPDT switches  70  and  74  causing switch positions shown in  FIG. 9 . Next the flash test is performed (step  203 ) using flash test module  20 . After the flash test of photovoltaic panel  10 , the bypass of electronic module  12  is de-activated by the removal of magnetic field  52  to SPST switch  50  and SPDT switches  70  and  74  (step  205 ).  FIG. 10  shows photovoltaic panel  10  connected to electronic module  12  with SPST switch  50  and SPDT switches  70  and  74  de-activated (step  205 ). 
         [0052]    During operation of electrical power generation system  14 , DC power is produced by photovoltaic panel  10  and transferred to the input of electronic module  12 . Electronic module  12  is typically a buck-boost converter circuit to perform DC to DC conversion or an inverter converting DC to AC or a circuit performing maximum power point tracking (MPPT). 
         [0053]    Reference is now made to  FIG. 12   a  which shows a module  12   a  connected to compensation unit  17   a  according to a feature of the present invention. Photovoltaic panel  10  is connected to the input of buck boost converter  12   a . The output of buck boost converter  12   a  is connected to compensation unit  17   a  at terminals A and the other terminals B of unit  17   a  is connected to conventional flash tester  17 . Fuse  50   a  provides a low impedance serial path between panel  10  and conventional flash tester  17 /compensation unit  17   a . With bypass link  50   a  applied (i.e. fuse link  50   a  is not blown), the shunt impedance (Z T ) of circuit  12   a  connected to conventional flash tester  17 /compensation unit  17   a  comes from capacitors C 1  and C 2  now connected in parallel in circuit  12   a  via link  50   a . If the total value of capacitance (C 1 +C 2 ) is large (typically around 50 micro-farads), the low shunt impedance Z T  may have a significant effect on the result of a flash test performed by tester  17  on panels  10 . 
         [0054]    Reference now made to  FIG. 12   b  which shows further details of compensation unit  17   a  according to a feature of the present invention. Compensation unit  17   a  has a programmable current injector  130 , circuit analyzer  128  and processor  126 . 
         [0055]    Programmable current injector  130  has a voltage source E  1  which may be connected to an electronic module  12 / 12   a  using terminals A. A first positive terminal of voltage source E 1  and a first negative terminal of voltage source E  1  provides terminals A. The first positive terminal of voltage source E  1  is connected to node P. A second positive terminal and a second negative terminal of voltage source E 1  is connected across a series connection of capacitor C p  and resistance R p  at node M and ground. One end of capacitor C p  connects to node M and the other end of capacitor C p  connects to one end of resistor R p  at node N. The other end of resistor R p  connects to ground. A first positive terminal of current source G 2  connects to node P and a first negative terminal of current source G 2  connects to ground. Terminals B are provided from connecting to node P and ground. A second positive terminal of current source G 2  connects to node N and a second negative terminal of current source G 2  connects to ground. 
         [0056]    The input to circuit analyzer  128  is derived from node P. The output of circuit analyzer  128  goes into the input of processor  126 . Processor  126  has two outputs (shown by dotted lines) which program/control current source G 2  and voltage source E 1 . Circuit analyzer  128  measures a circuit parameter of electronic module  12 / 12   a . The circuit parameter measured by circuit analyzer  128  is preferably the shunt impedance of electronic module  12 / 12   a . Processor  126  is preferably configured to program/control current injector  130  using the circuit parameter measured by circuit analyzer  128 . 
         [0057]    Reference is now made to  FIG. 12   c  and to  FIG. 12   d  according to a feature of the present invention.  FIG. 12   c  shows a simulation circuit  121   a  which has a pulse generator  120  with an output voltage and current  124  connected to a test circuit  122   a . Simulation circuit  121  is an equivalent circuit representation of a flash testing system. Pulse generator  120  is the equivalent circuit representation of a flash lamp  16  used to irradiate a photovoltaic panel  10  and test circuit  122   a  being the equivalent circuit representation of a photovoltaic panel  10 . Pulse generator  120  has a voltage V 1  which is a pulse of typically 33 volts peak, rise and fall time of 0.01 milliseconds and pulse duration of 0.54 milliseconds. The pulse from voltage V  1  is applied to test circuit  122   a  via resistor R g  which is connected in series between voltage V  1  and test circuit  122   a . Test circuit  122   a  has a resistance Rpm which is connected in series between the output of pulse generator  120  and ground.  FIG. 12   d  shows the simulation results of test circuit  122   a  as output voltage and current  124  as a result of pulse V  1  being applied to test circuit  122   a . Output voltage and current  124  has a peak voltage of 27V and current of 5.4 A which are in phase. 
         [0058]    Reference is now made to  FIG. 12   e  and to  FIG. 12   f  according to a feature of the present invention.  FIG. 12   e  shows a simulation circuit  121   b  which has a pulse generator  120  with an output voltage and current  124  connected to a test circuit  122   b . Simulation circuit  121   b  has the same elements as shown in  FIG. 12   b  but with the addition of a capacitor C m  connected in parallel with resistor R pm  in test circuit  122   b . Capacitor C m  in test circuit  122   b  represents the total shunt capacitance for example of module  12   a  connected to panel  10 .  FIG. 12   f  shows the simulation results of test circuit  122   a  as output voltage and current  124  of test circuit  122   b  as a result of pulse V 1  (33 volts peak, rise and fall time of 0.01 milliseconds and pulse duration of 0.54 milliseconds) being applied to test circuit  122   b . Output voltage and current  124  are now not in phase with voltage (27V) lagging and current peaks which reach 40 A. 
         [0059]    Reference is now made to  FIG. 12   g ,  FIG. 12   h  and  FIG. 12   i  according to a feature of the present invention.  FIG. 12   g  shows a simulation circuit  121   c  which has a pulse generator  120  with an output voltage and current  124  connected to a test circuit  122   b . Simulation circuit  121   c  has the same elements as shown in  FIG. 12   e  but with the addition of compensation unit  17   a  connected in parallel with capacitor C m  in test circuit  122   b . Capacitance C m  represents the total shunt capacitance for example of module  12   a  connected to panel  10  with bypass  50   a  activated as an un-blown fuse link (step  1201 ). In compensation unit  17   a , circuit analyzer  128  measures a circuit parameter of test module  122   b . The circuit parameter measured by circuit analyzer  128  is preferably the shunt impedance of test module  122   b  or the shunt capacitance of test module  122   b . Processor  126  is preferably configured to program/control current injector  130  using the circuit parameter measured by circuit analyzer  128 . Compensation unit  17   a  can inject a current into test module  122   b  in order to compensate for the shunt capacitance of test module  122   b  (step  1203 ) when performing a flash test.  FIG. 12   h  shows the compensated output voltage and current  124  of test circuit  122   b  as a result of pulse V 1  (33 volts peak, rise and fall time of 0.01 milliseconds and pulse duration of 0.54 milliseconds) being applied to test circuit  122   b . Output voltage and current  124  are now in phase and output voltage and current  124  represents the current/voltage characteristics of resistance Rpm in test circuit  122   b.    
         [0060]    Reference is now made again to  FIGS. 12   a ,  12   b  and to  FIG. 12   j  which shows a method  1220 , according to an embodiment of the present invention. With link  50   a  activated as an un-blown fuse link (step  1201 ) a low impedance path exists between the input and the output of module  12   a . Prior to a flash test of panel  10  using tester  17 , located in compensation unit  17   a , is circuit analyzer  128  which measures (step  1223 ) a circuit parameter of the output of electronic module  12   a  with the input of module  12   a  connected to pane  110 . The circuit parameter measured by circuit analyzer  128  with fuse link  50   a  connected according to step  1221  may be the impedance of capacitors C 1  and C 2  in parallel with panel  10  and with flash tester  17  disconnected. Alternatively, the value of shunt impedance for module  12   a  may be measured (to provide a noted value) prior to attachment to panel  10 . Processor  126  is preferably configured to program (step  1225 ) and/or control current injector  130  using the circuit parameter measured by circuit analyzer  128  or from the noted value. With flash tester  17  operatively attached to compensation unit  17   a , module  12   a  and panel  10 , a flash test is performed where the current injection by compensation unit  17   a  simultaneously triggers (step  1227 ) a flash test of a panel using tester  17 . 
         [0061]    The definite articles “a”, “an” is used herein, such as “a converter”, “a switch” have the meaning of “one or more” that is “one or more converters” or “one or more switches”. 
         [0062]    Although selected embodiments of the present invention have been shown and described, it is to be understood the present invention is not limited to the described embodiments. Instead, it is to be appreciated that changes may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and the equivalents thereof.