Description:FIELD OF INVENTION
[001] The field of invention generally relates to photovoltaic (PV) solar plants. More specifically, it relates to a system and method for automatic isolation of string combiner from solar inverter.

BACKGROUND
[002] Photovoltaic (PV) solar technology has seen significant growth over recent years as an efficient and sustainable for generating renewable energy. Solar PV systems are widely adopted for residential, commercial, and industrial applications, with installations ranging from rooftop solar panels to large-scale solar farms. As PV systems expand globally, there is a growing focus on enhancing their reliability, efficiency, and safety to meet increasing energy demands and ensure operational security.
[003] Currently, existing systems do not succeed in providing automatic isolation of the String Combiner Box (SCB) from the solar inverter in the event of a fault. In conventional systems, a DC isolator is commonly placed at the output of the SCB, enabling for manual disconnection of the DC source for maintenance or operational purposes. However, this design lacks the ability to automatically isolate the SCB from the inverter in case of electrical faults, such as ground faults. When such a fault occurs between the SCB and the inverter, the inverter may detect the issue and disconnect its internal circuits. However, the connection between the SCB and the inverter remains live, which can lead to high-current discharge and even short circuits, particularly in high-risk areas like rooftop installations. This limitation not only compromises system safety but also risks damage to equipment and potential hazards to personnel.
[004] Other existing systems have tried to address this problem. However, their scope was limited to manual isolation techniques or partial fault detection mechanisms that do not fully disconnect the SCB from the inverter. These methods often require human intervention, which can delay the response to a fault and may be ineffective in remote or hard-to-access locations. Additionally, some systems attempt to isolate only specific sections, but they fail to prevent heavy current discharge from other connected strings, which can lead to safety risks and potential equipment damage.
[005] Thus, in light of the above discussion, it is implied that there is need for a system and method for automatic isolation of string combiner from a solar inverter, which is reliable and does not suffer from the problems discussed above.
 
OBJECT OF INVENTION
[006] The principal object of this invention is to provide a system and method for automatic isolation of at least one string combiner from a solar inverter.
[007] Another object of the invention is to enable fault-specific isolation through an integrated DC molded case circuit breaker (MCCB) with a shunt trip coil.
[008] Another object of the invention is to provide a monitoring system through an inverter control card to continuously detect fault conditions in the photovoltaic solar unit.
[009] Another object of the invention is to reduce the need for manual intervention in fault isolation processes within solar power systems.
[0010] Another object of the invention is to prevent damage to the solar inverter and other system components by quickly isolating faulty sections.
[0011] Another object of the invention is to enhance the safety of photovoltaic solar systems, especially in installations with challenging access, such as rooftop or remote solar arrays.
[0012] Another object of the invention is to provide a robust system that integrates seamlessly with existing photovoltaic system components.

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] Figure 1 depicts/illustrates a block diagram of a system for isolating at least one String Combiner Box (SCB) from a solar inverter, in accordance with an embodiment;
[0016] Figure 2 depicts/illustrates a circuit diagram of a DC molded case circuit breaker (MCCB) , in accordance with an embodiment;
[0017] Figure 3 depicts/illustrates a circuit diagram for multiple DCMCCB’s, in accordance with an embodiment;
[0018] Figure 4 illustrates a method for isolating at least one String Combiner Box (SCB) from a solar inverter, in accordance with an embodiment.

STATEMENT OF INVENTION
[0019] The present invention discloses a system and method for automatic isolation of at least one string combiner from a solar inverter. The system comprises at least one solar panel string configured to generate a DC output, which is received by an SCB. The SCB consolidates the DC outputs into a single combined DC output and transmits it through a DC molded case circuit breaker (MCCB) with an integrated shunt trip coil. The DC MCCB is positioned between the SCB and the solar inverter and is configured to trip automatically in response to a tripping signal.
[0020] An inverter control card, disposed in the solar inverter, continuously monitors the PV solar unit for fault conditions, such as ground faults or short circuits. Upon detection of a fault, the control card transmits a fault-specific tripping signal to the shunt trip coil in the DC MCCB, thereby isolating the SCB from the inverter. This automated fault detection and isolation system reduces the need for manual intervention, enhances safety, and protects the solar inverter and related components from potential damage. The invention integrates seamlessly with existing PV system components, ensuring reliable and efficient operation.
 
DETAILED DESCRIPTION
[0021] 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.
[0022] The present invention relates to a system and method for automatically isolating a String Combiner Box (SCB) from a solar inverter in photovoltaic solar power systems. The system comprises solar panel strings generating DC power, an SCB that consolidates these DC outputs, a DC molded case circuit breaker (MCCB) with an integrated shunt trip coil, and an inverter control card within the solar inverter. The inverter control card continuously monitors for fault conditions, such as ground faults or short circuits, and, upon detection, sends a tripping signal to the MCCB. This signal activates the shunt trip coil in the MCCB, causing it to trip and isolate the SCB from the inverter. By automating the fault detection and isolation process, the invention enhances safety, reduces the need for manual intervention, and protects the inverter and other components from potential damage.
[0023] Figure 1 depicts/illustrates a system 100 comprising at least one solar panel string 102, at least one String Combiner Box 104, a DC molded case circuit breaker (MCCB) 106, a solar inverter 108, an inverter control card 110 and an inverter main DC input bus 112.
[0024] In an embodiment, the at least one solar panel string 102 arranged in an array, each solar panel string 102 is configured to generate a DC output. Each solar panel string 102 is configured to receive sunlight and convert it into DC electricity through photovoltaic cells. The solar panel array 100 generates a cumulative DC output which is fed to the String Combiner Box 104. Solar panel array 100 may vary in configuration, comprising at least one of monocrystalline, polycrystalline, or thin-film solar panels, among others, to suit different environmental and efficiency requirements.
[0025] In an embodiment, the String Combiner Box 104 is configured to receive DC outputs from the solar panel strings 102 and consolidate these outputs into a single combined DC output. The String Combiner Box 104 comprises multiple input terminals for receiving DC outputs from each solar panel string 102. The consolidated DC output from the String Combiner Box 104 is then transmitted to the DC molded case circuit breaker 106. String Combiner Box 104 may incorporate additional components, such as fuses and surge protection devices, to enhance safety and reliability of the DC output before it reaches the DC molded case circuit breaker 106.
[0026] In an embodiment, the DC molded case circuit breaker 106 is connected to the output of the String Combiner Box 104 and comprises an integrated shunt trip coil. DC molded case circuit breaker 106 is configured to automatically trip and isolate the String Combiner Box 104 from the solar inverter 108 in case of fault conditions, such as ground faults or short circuits. The shunt trip coil in the DC MCCB 106 enables circuit breaker to receive a tripping signal from the inverter control card 110, enabling for automated isolation without manual intervention. Alternatives to the DC molded case circuit breaker 106 may comprise other types of circuit breakers with shunt trip functionality that are suitable for handling high DC currents typical in photovoltaic unit.
[0027] In an embodiment, the solar inverter 108 is configured to receive the single consolidated DC output from the String Combiner Box 104 through the DC MCCB 106. Solar inverter 108 converts the DC power to alternating current (AC) power, making it suitable for grid use or powering AC loads. Inverter 108 comprises an inverter control card 110 and an inverter main DC input bus 112, both essential to invention’s fault detection and isolation functionality. Solar inverter 108 may comprise additional features, such as maximum power point tracking (MPPT) and temperature control mechanisms, to enhance performance and reliability in different operating conditions.
[0028] In an embodiment, the inverter control card 110 is disposed within the solar inverter 108 and is configured to monitor the DC power flow from the String Combiner Box 104. Inverter control card 110 detects fault conditions, such as ground faults or short circuits, within the photovoltaic solar unit. Upon detecting a fault condition, inverter control card 110 transmits a fault-specific tripping signal to the shunt trip coil in the DC MCCB 106, causing the DC MCCB 106 to trip and isolate the String Combiner Box 104 from the solar inverter 108. The inverter control card 110 may comprise advanced monitoring capabilities, such as real-time data analysis, and is compatible with various photovoltaic system configurations to ensure effective fault detection.
[0029] In an embodiment, the inverter main DC input bus 112 is part of the solar inverter 108 and is configured to receive the DC output from the String Combiner Box 104 via the DC MCCB 106. In case of a fault condition, the inverter main DC input bus 112 is isolated from the String Combiner Box 104 due to the tripping action of the DC MCCB 106, thereby preventing any further current flow from the String Combiner Box 104 to the solar inverter 108. This isolation protects the solar inverter 108 and associated components from potential damage caused by fault conditions.
[0030] In an example the system 100 comprises an array of solar panel strings 102 arranged on a rooftop installation to maximize sunlight exposure. Each solar panel string 102 is made of monocrystalline solar cells, chosen for their high efficiency. The combined DC output from these solar panel strings 102 is fed into a String Combiner Box 104 located near the solar panel string 102. The String Combiner Box 104 consolidates the DC output into a single DC output, which is then sent to a DC molded case circuit breaker 106 for safety control.
[0031] In this configuration, the DC MCCB 106 comprises a shunt trip coil that receives tripping signals from an inverter control card 110 disposed within the solar inverter 108. In case a ground fault is detected, the control card 110 transmits a tripping signal, causing the DC MCCB 106 to trip and disconnect the String Combiner Box 104 from the inverter main DC input bus 112 in the solar inverter 108. This ensures safe disconnection without manual intervention, protecting the system from potential electrical hazards.
[0032] In another example the system 100 is deployed in a large-scale solar farm where each solar panel string 102 comprises polycrystalline cells. The DC outputs from each solar panel string 102 are directed into the String Combiner Box 104, which consolidates the output into a single DC output for transmission to the DC MCCB 106. The DC MCCB 106 in this embodiment is configured to handle high DC currents typical of large-scale installations. The shunt trip coil in the DC MCCB 106 receives fault-specific tripping signals from the inverter control card 110 upon detection of a short circuit condition. The control card 110 continuously monitors the DC power flow to ensure any fault is quickly detected and isolated by tripping the DC MCCB 106, thus protecting the inverter main DC input bus 112 in the solar inverter 108 from overcurrent damage.
[0033] Figure 2 depicts/illustrates a circuit configuration for the DC molded case circuit breaker (MCCB) 106 with integrated shunt trip coil, along with the arrangement of the input and output terminals in the String Combiner Box 104.
[0034] In an embodiment, the DC molded case circuit breaker (MCCB) 106 is positioned to control the main DC output from the positive and negative busbars. MCCB 106 is equipped with an integrated shunt trip coil that enables remote tripping functionality. In case of fault conditions, the shunt trip coil receives a tripping signal from the inverter control card (not shown in Fig. 2), which activates the MCCB 106 to isolate the DC output. The MCCB 106, therefore, serves as a protective mechanism by disconnecting the String Combiner Box 104 from the downstream solar inverter.
[0035] In an embodiment, the shunt trip coil in the MCCB 106 is configured to receive a tripping signal, which prompts the MCCB 106 to trip and disconnect the SCB 104. This coil acts as the control component for the MCCB, enabling the inverter control card to trigger isolation automatically, without manual intervention.
[0036] Fig. 3 depicts/illustrates a configuration of multiple DC molded case circuit breakers (MCCBs) 106a, 106b, 106c, and 106d connected in series, each equipped with a shunt trip coil.
[0037] In an embodiment, the multiple DC MCCB is configured to manage a separate circuit path within the photovoltaic system. The MCCBs are connected in a configuration that enables coordinated tripping, controlled by the shunt trip coil. The primary function of each MCCB is to isolate its respective circuit path upon receiving a tripping signal, thereby preventing current flow and protecting the associated components in case of a fault. A primary shunt trip coil is positioned at the start of the series of MCCBs, labeled as 106a. This coil is responsible for receiving the tripping signal from an inverter control card (not shown in Fig. 3). Upon receiving this signal, the shunt trip coil activates and simultaneously initiates the tripping of MCCBs 106a, 106b, 106c, and 106d. This arrangement ensures that all connected MCCBs isolate their respective circuits in response to a single fault condition detected by the inverter control card.
[0038] In a large photovoltaic solar installation, multiple SCBs may be connected to a single inverter. If a ground fault is detected in one section, the inverter control card sends a signal to the primary shunt trip coil. The primary shunt trip coil activates MCCBs 106a, 106b, 106c, and 106d, isolating each associated SCB or section from the inverter, thus preventing damage across multiple circuits. This coordinated isolation minimizes risk of fault propagation and enhances the safety and reliability of the photovoltaic unit.
[0039] While the depicted configuration shows four MCCBs in series, alternative setups may comprise fewer or more MCCBs depending on the specific requirements of photovoltaic installation. Additionally, each MCCB may have its dedicated shunt trip coil, enabling for selective tripping based on the fault location, if more granular control is needed.
[0040] In an example, the system 100 utilizes thin-film solar panel strings 102, which are arranged in an array on a remote location with limited accessibility. The String Combiner Box 104 consolidates the DC outputs and sends them through the DC MCCB 106 to the solar inverter 108. In this configuration, the inverter control card 110 is equipped with remote monitoring capabilities, enabling for real-time monitoring and fault detection from a central control station. When the control card 110 detects a fault condition, such as an overvoltage, it sends a tripping signal to the shunt trip coil in the DC MCCB 106. The MCCB 106 automatically trips to isolate the String Combiner Box 104 from the solar inverter 108, thereby preventing further current flow through the inverter main DC input bus 112 and ensuring system's safety without requiring on-site intervention.
[0041] In an example the system 100 is installed in a solar plant setting where the solar panel strings 102 are arranged as part of a compact solar array. The String Combiner Box 104 consolidates the DC output from each solar panel string 102 and passes it through the DC MCCB 106 to the solar inverter 108. The inverter control card 110 is configured to detect both ground faults and temperature anomalies. Upon detecting a ground fault or temperature anomaly in the DC power flow, the inverter control card 110 transmits a tripping signal to the shunt trip coil in the DC MCCB 106. This causes the DC MCCB 106 to trip and disconnect the SCB 104 from the inverter main DC input bus 112 in the solar inverter 108, thereby ensuring a quick and automated isolation response to protect the residential solar system from potential hazards.
[0042] Figure 4 illustrates a method 400 for isolating at least one String Combiner Box (SCB) from a solar inverter. The method begins with generating a DC output from at least one solar panel string arranged in an array, as depicted at step 402. Subsequently, the method 400 discloses receiving and consolidating the DC outputs from the at least one solar panel string at into the SCB and consolidating the DC outputs into a single combined DC output, as depicted at step 404. Thereafter, the method 400 discloses transmitting the single combined DC output from the SCB to the solar inverter through a DC molded case circuit breaker (MCCB) having with an integrated shunt trip coil, as depicted at step 406. Thereafter, the method 400 discloses monitoring, by an inverter control card disposed in the solar inverter, for fault conditions in the photovoltaic solar unit, as depicted at step 408. Thereafter, the method 400 discloses detecting a fault condition by the inverter control card, as depicted at step 410. Thereafter, the method 400 discloses communicating a tripping signal from the inverter control card to the shunt trip coil in the DC MCCB upon detection of the fault condition, as depicted at step 412. Thereafter, the method 400 discloses tripping automatically the DC MCCB in response to the tripping signal, thereby isolating the SCB from the solar inverter, as depicted at step 414.
[0043] The advantages of the current invention include:
[0044] The invention provides automated detection and isolation of the String Combiner Box (SCB) from the solar inverter in response to fault conditions, ensuring quick and safe disconnection without manual intervention.
[0045] By isolating the SCB from the inverter upon detecting faults such as ground faults or short circuits, the system minimizes the risk of electrical hazards, protecting both equipment and personnel.
[0046] The invention enables continuous monitoring and quick isolation of faulty sections, reducing the likelihood of damage to critical components and ensuring stable, uninterrupted operation.
[0047] With automated fault detection and isolation, the need for manual intervention is significantly minimized, making the system particularly beneficial for installations in remote or difficult-to-access locations.
[0048] The DC molded case circuit breaker (MCCB) isolates the SCB from the inverter main DC input bus in case of faults, preventing fault currents from damaging the inverter and other connected components, thus extending their lifespan.
[0049] The integrated shunt trip coil in the DC MCCB enables for a rapid response to faults, ensuring that isolation occurs immediately upon fault detection, which helps prevent fault escalation.
[0050] The system is compatible with various types of solar panels, comprising monocrystalline, polycrystalline, and thin-film panels, making it adaptable for diverse photovoltaic installations.
[0051] The inverter control card continuously monitors the DC power flow and detects specific faults, enabling proactive monitoring and easier diagnostics, which can streamline maintenance efforts.
[0052] By isolating only the affected SCB rather than shutting down the entire system, the invention reduces downtime and maintains operational continuity for unaffected sections of the solar installation.
[0053] The quick isolation of faulty sections prevents further damage and reduces maintenance and repair costs associated with electrical faults, making the system more economical in the long term.
[0054] The invention is applicable to both large-scale solar farms and small residential solar systems, providing a scalable and efficient solution for different photovoltaic setups.
[0055] Applications of the current invention include:
[0056] The invention is highly suitable for large solar farms where multiple String Combiner Boxes (SCBs) and extensive solar panel arrays are used. The automated fault isolation system ensures quick response to faults, reducing the risk of widespread system failures and minimizing maintenance downtime.
[0057] For rooftop solar systems, particularly in commercial or industrial settings, the invention provides enhanced safety by automatically isolating faulty SCBs, which is crucial for installations in hard-to-access areas. This makes it ideal for urban solar deployments on buildings.
[0058] In remote or off-grid solar installations, such as those in rural areas or isolated locations, the invention reduces the need for manual fault handling, which may be challenging due to limited accessibility. The automated isolation and fault detection system enables for reliable operation with minimal human intervention.
[0059] The invention can be applied in residential solar systems to protect home inverters and other critical components. By providing automatic isolation in case of faults, it enhances safety for residential users and ensures continuous power availability for unaffected sections.
[0060] For floating solar farms installed on water bodies, where accessibility is even more challenging, the invention's automated fault detection and isolation features are beneficial. This application reduces the risk of electrical hazards in these unique environments and simplifies maintenance.
[0061] The invention is ideal for solar microgrids, which often operate in distributed configurations. By isolating faulty SCBs within the microgrid, the system maintains power flow to other parts of the network, ensuring stability and reliability across the grid.
[0062] Utility-scale solar installations can benefit from the invention’s quick fault response and isolation capabilities, protecting the infrastructure from faults and reducing downtime. The invention’s ability to work with high DC currents typical of large installations makes it a valuable asset for utility providers.
[0063] In agricultural applications, solar panels are often spread across large tracts of land. The invention enables for efficient fault management and reduces the risk of damage to inverters and other equipment, which is essential for maintaining continuous power supply for agricultural needs.
[0064] In industrial environments where solar power is used to support manufacturing or other energy-intensive operations, the invention provides robust protection for inverters and associated systems, enhancing operational stability and reducing potential disruptions.
[0065] For hybrid systems that combine solar with other energy sources, such as wind or battery storage, the invention ensures that faults in the solar portion are isolated without affecting the overall system, supporting seamless integration with other renewable energy sources.
[0066] 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.
, Claims:We claim:
1. A system for isolating at least one String Combiner Box (SCB) from a solar inverter, comprising:
at least one solar panel string (102) arranged in an array, wherein each solar panel string (102) is configured to generate a DC output;
the at least one String Combiner Box (SCB) (104) to receive and consolidate the DC output from the at least one solar panel string (102) into a single DC output;
a DC molded case circuit breaker (MCCB) (106) connected to the SCB (104), the DC MCCB (106) comprising an integrated shunt trip coil to trip and isolate the SCB from the solar inverter (108);
the solar inverter (108) configured to receive the single DC power from the SCB (104) through the DC MCCB (106); and
an inverter control card (110) disposed in the solar inverter (108), to detect a fault condition in a photovoltaic solar unit and to transmit a tripping signal to the DC MCCB (106) to isolate the SCB (104) from the solar inverter (108).

2. The system as claimed in claim 1, wherein the inverter control card (110) is configured to transmit a fault-specific tripping signal to the shunt trip coil in the DC MCCB (106) upon detection of a fault condition, thereby causing the DC MCCB (106) to automatically isolate the SCB (104) from the solar inverter (108).

3. The system as claimed in claim 1, wherein the inverter control card (110) is configured to monitor the DC power flow from the SCB (104) to detect at least one of ground fault, and short circuits in the PV unit.

4. The system as claimed in claim 1, wherein the DC MCCB (106) is connected between the SCB (104) and the solar inverter (108), to enable isolation of the SCB (104) from the solar inverter (108) upon detection of a fault condition.

5. A method for isolating at least one String Combiner Box (SCB) (104) from a solar inverter (108), comprising:
generating a DC output from at least one solar panel string (102) arranged in an array;
receiving and consolidating the DC output from the at least one solar panel string (102) into the SCB (104);
transmitting the single DC output from the SCB (104) to the solar inverter (108) through a DC molded case circuit breaker (MCCB) (106) with an integrated shunt trip coil;
monitoring, by an inverter control card (110) disposed in the solar inverter (108), for fault conditions in the photovoltaic solar unit;
detecting a fault condition by the inverter control card (110);
communicating a tripping signal from the inverter control card (110) to the shunt trip coil in the DC MCCB (106) upon detection of the fault condition;
tripping the DC MCCB (106) in response to the tripping signal, thereby isolating the SCB (104) from the solar inverter (108).

6. The method as claimed in claim 5, comprising monitoring the DC power flow from the SCB (104) by the inverter control card (110) to detect at least one of a ground fault and a short circuit in the photovoltaic solar unit.

7. The method as claimed in claim 5, comprising enabling isolation of the SCB (104) from the inverter (108) upon fault detection by connecting the DC MCCB (106) between the SCB (104) and the solar inverter (108).

8. The method as claimed in claim 5, comprising activating the shunt trip coil in the DC MCCB (106) by the inverter control card (110) in response to detecting a ground fault condition between the SCB (104) and the solar inverter (108).

Date: 15th November, 2024 Signature:

Name of signatory: Nishant Kewalramani
(Patent Agent) IN/PA number: 1420