Description:[001] The field of invention generally relates to potential induced degradation (PID) detection and reversal in solar modules. More specifically, it relates to a system and method for potential induced degradation detection based on solar module positioning, its reversal and control by real time monitoring on supervisory control and data acquisition (SCADA).

BACKGROUND
[002] Potential-Induced Degradation (PID) is a common phenomenon that causes solar module strings to lose up to 80% of their power generation. Power reduction can happen over time or within days or weeks of installation.
[003] Typically, if the positive terminal of the string is used as system ground and the mounting structure is connected to the earth potential, the cell closest to the positive terminal has the least negative potential with respect to earth and thus the least PID effect.
[004] On the other hand, the cell closest to the negative terminal will have a high negative potential relative to the grounded structure and will experience the most PID. As a result, cells, modules, and panels will experience PID based on their position in the string.
[005] The PID process in the solar module can grow very quickly, affecting the overall performance of the solar module system in the shortest amount of time.
[006] Therefore, it is essential to detect and address the PID problem in its early stages, to ensure solar module performance over the entire system. Furthermore, PID can be prevented and recovered on system level altogether.
[007] Currently, existing systems do not succeed in real time monitoring of PID in solar modules as a preventive control measure to mitigate and reverse PID effect.
[008] Other existing systems have tried to address this problem. However, their scope was limited to usage of solar modules which are resistant to PID. As a result, the cost will be higher due to use of more expensive encapsulating materials, anti-reflective coatings, and other materials.
[009] Thus, in light of the above discussion, it is implied that there is need for a system and method for PID detection and reversal based on solar module positioning, which is reliable and does not suffer from the problems discussed above.

OBJECT OF INVENTION
[0010] The principal object of this invention is to provide a system and method for PID detection and reversal based on solar module positioning.
[0011] A further object of the invention is to provide a system and method for real time monitoring of PID in solar modules as a preventive control measure to mitigate and reverse PID effect.
[0012] Another object of the invention is to increase the solar module performance by reversing the PID effect.

BRIEF DESCRIPTION OF FIGURES
[0013] This invention is illustrated in the accompanying drawings, throughout which, like reference letters indicate corresponding parts in the various figures.
[0014] The embodiments herein will be better understood from the following description with reference to the drawings, in which:
[0015] Fig. 1 depicts/ illustrates a general block diagram of system for PID detection and reversal based on solar module positioning, in accordance with an embodiment of the present disclosure;
[0016] Fig. 2 depicts/ illustrates a block diagram representation of components enclosed in the system for PID detection and reversal based on solar module positioning, in accordance with an embodiment of the present disclosure;
[0017] Fig. 3a depicts/ illustrates a pictorial representation of fuse and inverter, in accordance with an embodiment of the present disclosure;
[0018] Fig. 3b depicts/ illustrates a negative grounding kit in ABB inverter, in accordance with an embodiment of the present disclosure;
[0019] Fig. 4a depicts/ illustrates a negative to ground voltage status in the inverter before fuse replacement, in accordance with an embodiment of the present disclosure;
[0020] Fig. 4b depicts/ illustrates a negative to ground voltage status in the inverter after fuse replacement, in accordance with an embodiment of the present disclosure;
[0021] Fig. 5a depicts/ illustrates a negative to ground voltage and resistance measurement in the inverter before fuse replacement, in accordance with an embodiment of the present disclosure;
[0022] Fig. 5b depicts/ illustrates a negative to ground voltage and resistance measurement in the inverter after fuse replacement, in accordance with an embodiment of the present disclosure;
[0023] Fig. 6a depicts/ illustrates a scatter plot of modules degradation based on positioning on structure for Srinivaspur site, in accordance with an embodiment of the present disclosure;
[0024] Fig. 6b depicts/ illustrates a scatter plot of modules degradation based on positioning on structure for Kanakagiri site, in accordance with an embodiment of the present disclosure;
[0025] Fig. 7a depicts/ illustrates a graphical representation of expected and average power degradation for Srinivaspur site, in accordance with an embodiment of the present disclosure;
[0026] Fig. 7b depicts/ illustrates a graphical representation of expected and average power degradation for Kanakagiri site, in accordance with an embodiment of the present disclosure;
[0027] Fig. 8 depicts/ illustrates a method for PID detection and reversal based on solar module positioning, in accordance with an embodiment of the present disclosure;

STATEMENT OF INVENTION
[0028] The present invention discloses a system and method for PID detection and reversal based on solar module positioning. The system comprises at least one user device, at least one solar string module, a PID detection and reversal module and a communication network. The at least one solar string module is configured to connect a group of solar modules in series.
[0029] The at least one user device comprises a PID analysis unit, an alert unit, a SCADA unit, a communication unit, a processing unit, and a memory unit. The PID detection and reversal module comprises a testing module and a switching module.
[0030] The testing module is configured to detect potential induced degradation (PID) based on solar module positioning on the structure. The PID analysis unit is configured to analyze the power degradation percentage based on module positioning on the structure. The alert unit is configured to generate alerts based on detection of module degradation in a solar module system.
[0031] The switching module is configured to reverse the PID effect by switching the polarity from the negative side of the string to the positive side of the string, by switching the position of the solar modules. The SCADA unit is configured to facilitate real-time monitoring of PID effect and negative grounding for the inverter as well as a history of the inverter's events to determine the health of the inverter's negative grounding.
 
DETAILED DESCRIPTION
[0032] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and/or detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0033] The present invention discloses a system and method for PID detection and reversal based on solar module positioning. The present invention discloses a method for testing the solar modules for power degradation. Further, the power degradation can be reversed by switching the affected modules from the negative side of the string to the positive side of the string.
[0034] Fig. 1 depicts/ illustrates a general block diagram of system for PID detection and reversal based on solar module positioning, in accordance with an embodiment of the present disclosure;
[0035] In an embodiment, the system 100 comprises at least one user device 102, at least one solar string module 104, a PID detection and reversal module 106 and a communication network 108.
[0036] In an embodiment, the at least one user device 102 may comprise one or more of wearable device, mobile phones, PDA, smartphones, smart band, smart watch, laptop, computer, etc.
[0037] The at least one solar string module 104 configured to connect a group of solar modules in series. The at least one solar string module 104 is further connected to a string monitoring box (SMB).
[0038] The PID detection and reversal module 106 is configured to detect and reverse the PID effect in the at least one solar string module 104.
[0039] The communication network 108 of the at least one user device 104 may include wired and wireless communication, including but not limited to, GPS, GSM, LAN, Wi-Fi compatibility, Bluetooth low energy as well as NFC. The wireless communication may further comprise one or more of Bluetooth (registered trademark), ZigBee (registered trademark), a short-range wireless communication such as UWB, a medium-range wireless communication such as Wi-Fi (registered trademark) or a long-range wireless communication such as 3G/4G or WiMAX (registered trademark), according to the usage environment.
[0040] Fig. 2 depicts/ illustrates a block diagram representation of components enclosed in the system for PID detection and reversal based on solar module positioning, in accordance with an embodiment of the present disclosure;
[0041] The at least one user device 102 comprises a PID analysis unit 202, an alert unit 204, a SCADA unit 206, a communication unit 208, a processing unit 210, and a memory unit 212.
[0042] The PID analysis unit 202 is configured to analyze the power degradation based on solar module positioning. According to the PID analysis, the negative side of the strings degrades power by an average of 2% more than the positive side of the string. The negative side of the modules suffers from high negative polarity-related power degradation due to PID effect. Using scatter plots and other excel features, the results of the IV test were examined to verify the hypotheses. In an embodiment, any software application that is known in the art may be utilized to analyze the results of an IV test.
[0043] The alert unit 204 is configured to generate alerts based on detection of module degradation in a solar module system. The alert unit 204 may trigger alert when the degradation crosses a predefined limit. The predefined limit may be customized by the user through the user device 102.
[0044] In an embodiment, the alert unit 204 may be resided within the user device 102. In another embodiment, the alert unit 204 may be resided within the PID detection and reversal module 106.
[0045] The SCADA unit 206 is configured to facilitate real-time monitoring of PID effect and negative grounding for the inverter 304 as well as a history of the inverter's 304 events to determine the health of the inverter's 304 negative grounding.
[0046] The solar module system is vulnerable to PID-induced degradation if there is negative to ground voltage at the inverter end, which must be zero in order for the PID effect to not be present. Therefore, it is necessary to monitor the negative to ground voltage and the condition of the negative to ground fuse for PID monitoring. This monitoring is a precautionary measure to have better PID control.
[0047] In an embodiment, the communication unit 208 of the user device 102 may include wired and wireless communication, including but not limited to, GPS, GSM, LAN, Wi-Fi compatibility, Bluetooth low energy as well as NFC. The wireless communication may further comprise one or more of Bluetooth (registered trademark), ZigBee (registered trademark), a short-range wireless communication such as UWB, a medium-range wireless communication such as Wi-Fi (registered trademark) or a long-range wireless communication such as 3G/4G or WiMAX (registered trademark), according to the usage environment.
[0048] In an embodiment, the processing unit 210 may comprise one or more of microprocessors, circuits, and other hardware configured for processing. The processor 210 is configured to execute instructions stored in the memory unit 212 as well as communicate with user devices 102 via the communication unit 208.
[0049] In an embodiment, the memory unit 212 of the user device 102 comprises one or more volatile and non-volatile memory components which are capable of storing data and instructions to be executed.
[0050] The PID detection and reversal module 106 comprises a testing module 214 and a switching module 216.
[0051] The testing module 214 is configured to detect potential induced degradation (PID) based on solar module positioning on the structure. The testing module 214 may comprise at least one of an IV-Tester, an EL Imaging, an Infrared (IR) or Thermography, and a statistical mathematical method among others.
[0052] In the preferred embodiment, IV-Tester is used for detecting PID. I-V tester is configured to sweep an electrical load connected to the solar module or string and measure both the current and voltage at multiple points during the sweep.
[0053] In an embodiment, the PID detection and reversal module 106 may be resided within the user device 102. In another embodiment, the PID detection and reversal module 106 may be a stand-alone device.
[0054] The switching module 216 is configured to switch the polarity from the negative side of the string to the positive side of the string, by switching the position of the modules.
[0055] The switching of position of modules may be done either manually or automatically.
[0056] Fig. 3a depicts/ illustrates a pictorial representation of fuse and inverter, in accordance with an embodiment of the present disclosure;
[0057] Each solar module is connected in series to the inverter 304. The inverter 304 combines all the direct current received from each individual solar module and, at once, converts it into alternating current.
[0058] For an early detection of PID in the solar module, negative grounding is enabled in the inverters 304. All the inverters are monitored at the SCADA unit 206 for real time monitoring. In a healthy negative ground fuse, the negative to ground voltage at the inverter should be zero. If the fuse 302 blows, however, the negative to ground value will be roughly 330V, which also puts the solar module system at risk of PID.
[0059] The negative grounding fuse 302 normally gets blown in case of ground fault tripping of the inverter, which is a protection that prevents and detects current leakage via some loose connection or grounding of the cables, connectors, and water ingress during rain. Under ideal conditions, the inverters must not run when the fuse 302 is blown. However, it has been observed in some makes and specifications of inverters that the inverters continue to run even when the fuse 302 is blown, leading to a negative to ground voltage of almost 330 volts flowing in the system and a PID effect in modules. Once the fuse 302 is blown, the inverter runs without ground fault protection, increasing the risk of potential discharge via the module frame, causing PID.
[0060] In an embodiment, the historical data of fuse 302 failure for inverters 304 are analyzed, which will help to prevent PID by proper negative grounding control. The historical data is obtained from SCADA unit 206 via a daily report. If the negative to ground voltage is above zero, then the negative grounding function of the inverter is not working, which could be due to the negative grounding fuse blowing, putting the module system at risk of potential induced degradation. Thus, by actively checking the report daily, it can be confirmed if the inverter negative grounding fuse protection is enabled.
[0061] In the preferred embodiment, the inverter 304 used may be SG2500 Sungrow Inverter 304. It will run even when there is leakage current, which leads to PID losses. The SCADA unit 206 detects this anomaly in real time.
[0062] Furthermore, if inverter 304 is running with leakage current, this also leads to reduction in inverter lifetime as well. The SCADA unit 206 can also monitor such leakage current on real time.
[0063] Additionally, the generation losses due to inverter tripping on fuse 302 failure cases will be restored faster than earlier, due to real time monitoring at the SCADA unit 206.
[0064] Fig. 3b depicts/ illustrates a negative grounding kit in ABB inverter, in accordance with an embodiment of the present disclosure;
[0065] In an embodiment, a negative grounding kit is available in ABB inverters, to counter the existing PID losses. The negative input of the inverter is provided with a fuse 302 connection and grounded via means of a scalable resistor 306. Current and voltage measurement are taken as shown in the fig. 3b.
[0066] Fig. 4a depicts/ illustrates a negative to ground voltage status in the inverter before fuse replacement, in accordance with an embodiment of the present disclosure;
[0067] The negative to ground voltage greater than 0V indicates fuse 302 failure.
[0068] Fig. 4b depicts/ illustrates a negative to ground voltage status in the inverter after fuse replacement, in accordance with an embodiment of the present disclosure;
[0069] The negative to ground voltage of 0V indicates healthy solar modules.
[0070] Fig. 5a depicts/ illustrates a negative to ground voltage and resistance measurement in the inverter before fuse replacement, in accordance with an embodiment of the present disclosure;
[0071] Fig. 5b depicts/ illustrates a negative to ground voltage and resistance measurement in the inverter after fuse replacement, in accordance with an embodiment of the present disclosure;
[0072] The negative to ground voltage and resistance measurement are made available at the SCADA unit 206 in real time, which helps to monitor real time data and prevent PID effect due to negative grounding fail.
[0073] Fig. 6a depicts/ illustrates a scatter plot of modules degradation based on positioning on structure for Srinivaspur site, in accordance with an embodiment of the present disclosure;
[0074] The modules on the far end of the string as shown in fig 6a is showing higher degradation, which is the negative side of the string and that can be attributed to PID related degradation. The table 1 below depicts the power degradation percentage of solar string module.

Module count % Power degradation
0 to 10 5.35%
11 to 20 7.30%
Table 1: Power degradation % in Srinivaspur site

[0075] Fig. 6b depicts/ illustrates a scatter plot of modules degradation based on positioning on structure for Kanakagiri site, in accordance with an embodiment of the present disclosure;
[0076] In fig 6b there is no clear trend of power degradation for the modules along positive or negative side of the string, the power degradation is showing uniform trend, showing no PID induced degradation for Kanakagiri site where the modules have been switched to control the PID. Same can be seen from the average power degradation value in table 2 given below.
Module count % Power degradation
0 to 10 4.31%
11 to 20 4.35%
Table 2: Power degradation % in Kanakagiri site

[0077] Fig. 7a depicts/ illustrates a graphical representation of expected and average power degradation for Srinivaspur site, in accordance with an embodiment of the present disclosure;
[0078] For Srinivaspur site, there is significant increase in the power degradation on the negative side of the strings, showing significant PID induced power degradation presence. Power delta of almost 2% was observed between positive and negative side of the string.
[0079] Fig. 7b depicts/ illustrates a graphical representation of expected and average power degradation for Kanakagiri site, in accordance with an embodiment of the present disclosure;
[0080] For Kanakagiri site, no difference between the negative and positive side string degradation has been observed, the site is showing lower power degradation than expected. Power delta of just 0.04% was observed, showing no PID induced degradation.
[0081] Fig. 8 depicts/ illustrates a method for PID detection and reversal based on solar module positioning, in accordance with an embodiment of the present disclosure;
[0082] The method 800 begins with testing the solar string modules for module degradation by using a testing module, as depicted at step 802. Subsequently, the method 800 discloses analyzing the module degradation of solar string modules by using an analysis unit, as depicted at step 804. Thereafter, the method 800 discloses switching the position of solar modules for reversing the module degradation by using a switching module, as depicted at step 806. Thereafter, the method 800 discloses monitoring the module degradation and negative side grounding voltage of inverter in real time as a preventive control measure by using a SCADA unit, as depicted at step 808.
[0083] The advantages of the current invention include detection and reversal of PID induced module degradation and increase in the solar module performance.
[0084] An additional advantage is that the real time monitoring of inverter negative side grounding voltage in SCADA.
[0085] Applications of the current invention include solar module PID induced degradation detection, reversal & real time monitoring.
[0086] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the scope of the embodiments as described here.

, C , Claims:We claim:
1. A system (100) for PID detection and reversal based on solar module positioning, comprising:
at least one solar string module (104) configured to connect a group of solar modules;
a PID detection and reversal module (106) configured to detect and reverse the potential induced degradation in the at least one solar string module (104); and
at least one user device (102) that is in communication with the PID detection and reversal module (106), wherein the at least one user device (102) comprises:
a PID analysis unit (202) configured to analyze the power degradation of the at least one solar string module (104) based on module positioning; and
a SCADA unit (206) configured to facilitate real-time monitoring of PID effect and negative grounding for an inverter (304).

2. The system (100) as claimed in claim 1, wherein the at least one solar string module (104) is connected to a string monitoring box (SMB).

3. The system (100) as claimed in claim 1, wherein the at least one user device (102) comprises an alert unit (204) configured to generate alerts based on detection of module degradation in the system (100).

4. The system (100) as claimed in claim 1, wherein the PID detection and reversal module (106) comprises:
a testing module (214) configured to test the solar modules for potential induced degradation (PID) based on solar module positioning on the structure; and
a switching module (216) configured to reverse module degradation by switching the polarity of the at least one solar string module (104) from the negative side of the string to the positive side of the string, by switching the position of the at least one solar string module (104).

5. The system (100) as claimed in claim 1, wherein the SCADA unit (206) is configured to monitor the negative to ground voltage and resistance measurement of the inverter (304) in real time to prevent PID effect due to negative grounding fail.

6. A method (800) for PID detection and reversal based on solar module positioning, comprising:
testing at least one solar string module (104) for module degradation;
analyzing a module degradation of the at least one solar string module (104);
switching the position of the at least one solar string module (104) for reversing the module degradation;
monitoring the module degradation and negative side grounding voltage of inverter (304) in real time as a preventive control measure;

7. The method (800) as claimed in claim 6, comprising:
testing the at least one solar string module (104) for module degradation by using a testing module (214);
analyzing the module degradation of the at least one solar string module (104) by using a PID analysis unit (202);
switching the position of the at least one solar string module (104) for reversing the module degradation by using a switching module (216);
monitoring the module degradation and negative side grounding voltage of inverter (304) in real time as a preventive control measure by using a SCADA unit (206);

8. The method (800) as claimed in claim 6, comprising connecting the at least one solar string module (104) to a string monitoring box (SMB).

9. The method (800) as claimed in claim 6, comprising configuring the at least one user device (102) to generate alerts based on detection of module degradation in a solar module system by using an alert unit (204).

10. The method (800) as claimed in claim 6, comprising configuring the SCADA unit (206) to monitor the negative to ground voltage and resistance measurement of the inverter (304) in real time to prevent PID effect due to negative grounding fail.