1. Product Overview

The PV combiner box is a core device that connects the PV module array to the inverter, widely used in solar photovoltaic power generation systems. In a large-scale PV system, a large number of PV modules must be connected in series and parallel to achieve the desired voltage and current levels. The main function of the PV combiner box is to perform primary combining of the inputs from the PV module strings, reducing the number of cables connecting the PV array to the inverter, optimizing system structure, and improving system reliability and maintainability.

The product is widely used in large-scale centralized PV power stations, distributed PV systems, commercial & industrial rooftop PV, and residential PV applications, and is exported to more than 60 countries and regions worldwide.

2. Core Functions

2.1 Current Collection and Primary Combining

Collects DC current from multiple PV strings onto a common busbar, then transmits it to the inverter via the main cable, effectively reducing cable usage and system wiring complexity.

2.2 Multiple Protection Functions

• Overcurrent protection: Uses dedicated PV DC fuses or circuit breakers. When overcurrent or short circuit occurs on a branch, the protection device immediately trips to isolate the faulty branch, preventing abnormal current from entering the bus and affecting the entire system.

• Reverse current protection: Equipped with anti-reverse diodes to prevent energy from other strings flowing back into a shaded or faulty string, avoiding module damage.

• Surge protection: Uses Type 1 combined SPD with response time <25ns. When lightning or other external high-energy surges occur, the SPD quickly diverts excess energy to ground, protecting sensitive internal components.

• Insulation monitoring: Continuously monitors positive and negative insulation resistance to ground using an unbalanced bridge principle, with detection sensitivity ≤500kΩ, preventing DC-side ground faults that could cause fire or electric shock.

2.3 Intelligent Monitoring Functions

• Current measurement per PV string, isolated measurement with accuracy up to ±1%

• Monitoring of total voltage, total current, and total power after combining

• Branch power monitoring and open-circuit alarm

• SPD status collection, DC circuit breaker status collection

• Temperature sensor for real-time monitoring of internal box conditions (alarm threshold typically set at 55°C)

3. Technical Specifications

3.1 Main Technical Parameter Table

(The above parameters are typical ranges; refer to specific manufacturer datasheets for exact values.)

4. Product Advantages

4.1 High-Quality Core Components

Uses PV-dedicated DC fuses with DC 1kV voltage withstand and selectable fusing current. Optional use of DC circuit breakers, DC fuses, surge protection devices, and other components from well-known domestic and international brands according to customer requirements.

4.2 High-Precision Measurement Technology

Measurement components use Hall sensors with isolated measurement, supporting up to 20 inputs. High measurement accuracy and strong anti-interference capability. Optional voltage measurement function with maximum measured voltage DC 1.5kV.

4.3 High Protection Rating

Protection rating up to IP65 or higher, meeting installation requirements for various indoor and outdoor environments. For extreme environments such as deserts and gobi areas, IP66 protection rating and C5 or higher corrosion protection level are available, with nickel-plated and potting processes to enhance corrosion and moisture resistance.

4.4 Flexible Power Supply Options

Multiple power supply methods available (DC24V, AC/DC220V, DC1000V), suitable for various applications from residential rooftop solar to professional PV power plants.

4.5 Intelligent Operation & Maintenance

Features open-circuit alarm and status detection for PV strings. Includes digital inputs for collecting status of DC circuit breakers, SPDs, and other components. Relay output can be configured for momentary action to drive automatic opening/closing of DC circuit breakers. Local digital display cycles through input current of each channel, with automatic energy-saving display mode.

4.6 Modular Design

Modular structure design for easy installation and maintenance. Hardware includes temperature sensor interface and LED display. Enclosure uses double-folded box body and waterproof cable glands to improve protection performance.

5. Selection Guide

When selecting a PV combiner box, consider the following aspects:

1. Electrical parameter matching: The combiner box must withstand the maximum DC voltage generated by the series-connected PV modules and have adequate current carrying capacity. Sufficient margin should be reserved to ensure no overload during long-term operation.

2. Number of branches: Determine the required number of branches based on project size and module layout. Consider possible future expansion needs.

3. Protection rating: PV combiner boxes are typically installed outdoors and require IP65 or higher dust and water ingress protection to prevent damage to internal components from rain, dust, and corrosive substances.

4. Environmental adaptability: Fully consider the local climate conditions including temperature range, humidity, altitude, salt spray corrosion level, etc., and select equipment with appropriate environmental adaptability.

5. Protection functions: Ensure the device has multiple protection measures including overcurrent, short circuit, reverse current, and surge protection.

6. Communication and intelligence requirements: Depending on the O&M management model of the power station, decide whether intelligent monitoring and remote communication functions are needed. Smart combiner boxes can significantly reduce manual inspection costs and improve fault response efficiency.

6. Frequently Asked Questions

Q1: What does IP65 protection rating mean for a combiner box?

A: IP65 means the device is completely dust-tight (no dust ingress) and protected against low-pressure water jets from any direction, fully meeting outdoor installation requirements.

Q2: What is the difference between a DC combiner box and an AC combiner box?

A: A DC combiner box collects DC power from PV modules and sends it to the inverter. An AC combiner box collects AC power from multiple inverters before grid connection. They are located at different points in the system and have different protection component selections.

Q3: What is the main difference between a smart combiner box and a conventional combiner box?

A: A smart combiner box integrates online measurement modules for current, voltage, insulation, temperature, etc., plus a communication unit, enabling remote monitoring, fault location, intelligent alarms, and data analysis, greatly improving O&M efficiency.

Q4: Does a combiner box require regular maintenance?

A: Yes. Regular inspection of SPD status, fuses and circuit breakers, tightness of terminals, and enclosure sealing is recommended to ensure long-term reliable operation.

Q5: Can the combiner box be customized?

A: Yes. Mainstream manufacturers support customization of number of inputs, rated current, protection rating, communication method, and component brand selection according to customer requirements.