Outdoor Photovoltaic Grid-Connected Junction Box

Outdoor photovoltaic grid-connected junction boxes are used between the DC side of a photovoltaic power generation system and the inverter. If you want to customize this product at a competitive price, you can choose Shangming, and we will become your trusted supplier.

Core Functions

The outdoor photovoltaic grid-connected junction box integrates protection, isolation, and monitoring. We support customized circuit numbers, branded components, and intelligent functions. For specific configuration solutions and quotations, please contact us.

1. String Busing and Current Distribution

PV power plants consist of multiple solar panels connected in series. The grid-connected junction box serves as a converging and shunting protection mechanism.

Converging Function: It gathers the DC power from multiple strings onto a single bus for output to the inverter, simplifying wiring and saving on DC cable costs.

Shunting Protection: Each input is equipped with an independent DC fuse. When a short circuit occurs in one string, the fault is confined to that branch, without affecting the normal power generation of other strings.

2. Lightning and Surge Protection

Because photovoltaic panels are installed on open rooftops or the ground, they are highly susceptible to lightning strikes. The surge protector integrated inside the junction box can sense instantaneous high voltages in the line and discharge the overvoltage to the ground within nanoseconds.

It serves as the first line of defense before the inverter, preventing induced lightning strikes that could damage the inverter's electronic components.

3. Safety Isolation and Physical Disconnection

The enclosure is equipped with a high-voltage DC isolating switch or circuit breaker. When maintenance is required on the inverter or downstream equipment, manually disconnecting the junction box ensures the maintenance side is completely de-energized, protecting personnel safety.

Shangming's grid-connected enclosure is high-performance and reliable, allowing for safe current interruption while the system is running, preventing the generation of dangerous arcs that could cause a fire.

4. Reverse Charging Protection

In the morning, evening, or on cloudy days, the output voltage of different strings may differ. Without protection, strings with higher voltage can flow current back into strings with lower voltage.

Optional reverse charging diodes are available, ensuring current flows only unidirectionally to the inverter, preventing localized overheating or even fire caused by reverse current.

5. Environmental Protection and Condition Monitoring

Because this product is to be installed outdoors, the enclosure has an IP65/IP66 protection rating to prevent rainwater corrosion and UV aging. The internal precision components operate reliably throughout the 25-year lifespan of the power station.

Optional intelligent monitoring function monitors the current, voltage, and internal temperature of each string in real time, and immediately alarms in case of abnormal power generation.

Why Must Photovoltaic Grid-Connected Junction Boxes Be Waterproof for Outdoor Use?

PV systems are typically installed on rooftops or in open fields, and the grid-connected junction boxes must withstand the following severe challenges:

Extreme temperature variations: Summer temperatures can reach over 70°C, while winter temperatures can drop to -30°C.

UV radiation: Long-term outdoor exposure to sunlight requires UV stability; otherwise, they are prone to aging.

Moisture and condensation: They must be rainproof and equipped with a breather valve to drain internal condensation and prevent electrical components from getting damp.

Therefore, for normal use and to avoid frequent maintenance during operation, maintaining stable performance and lifespan, an outdoor waterproof design is essential.

Application Scenarios and Configuration Recommendations

Shangming's outdoor photovoltaic grid-connected junction boxes can be used throughout the entire photovoltaic industry chain, from residential rooftops to large-scale ground-mounted power stations. We will provide configuration recommendations based on common scenarios.

1. Residential Distributed Photovoltaic Systems

This type of use is very common, generally installed on the roofs or walls of villas or self-built houses in rural areas. It collects several photovoltaic panels from different orientations on the roof and provides basic lightning protection.

Configuration Recommendations: The box should have a clean appearance and small size, 1-4 string inputs, and be equipped with highly sensitive fire protection monitoring.

2. Industrial and Commercial Rooftop Power Stations

In this case, the grid-connected box is installed on the flat roofs of factory workshops, logistics warehouses, or large shopping malls. For medium-sized power generation capacity, it pre-combines dozens of photovoltaic strings before they enter a string inverter.

Configuration Recommendations: The box needs high corrosion resistance, 8-16 string inputs, and usually includes a smart communication module to facilitate maintenance personnel to view the current of each branch in the monitoring room.

3. Large-scale Ground-mounted Power Stations and Solar Deserts

Gathering boxes distributed in deserts, mountains, or large open spaces are called combiner boxes. As primary combiner devices, they collect the current from thousands of solar panels and transmit it to a centralized inverter.

Configuration Recommendation: IP66, dedicated to 1500V high-voltage systems, equipped with anti-reverse diodes and precise string monitoring functions, and featuring active cooling/breathing valves.

4. Solar + Cross-border Application Scenarios

Solar Carports: Provide power to electric vehicle charging stations. The junction box is installed on the carport pillars to protect downstream charging stations from solar surges.

Agricultural Solar and Fishery Solar Complementary Systems: Installed on brackets above farmland or fishponds. Special requirements exist for moisture resistance and acid/alkali corrosion resistance; stainless steel is recommended.

Why Choose Us?

Shangming originates from Yueqing, Wenzhou, China, a region renowned as the "Electrical Capital of China." Leveraging the well-developed industrial chain of Yueqing's electrical industry cluster, we have established a rigorous and efficient production and quality control system. Our product portfolio covers over 200 series and 6000+ models, conforming to mainstream global electrical standards.

Choosing our intelligent complete sets of equipment integrates IoT sensing and remote monitoring functions, enabling real-time monitoring of parameters such as temperature, humidity, and current. This ensures stable operation and safe power supply.