EXCB1-DC2-1 2 PV Combiner Box 2 In 1 Out

EXCB1-DC2-1 PV Combiner Box 2 In 1 Out.
Easier to Wire Your Dual-String PV System

The HUYU Electric
EXCB1-DC2-1 PV combiner box 2 in 1 out is designed to provide protection for small-scale photovoltaic (PV) systems with two DC strings operating in parallel within a compact footprint. The combiner box is built specifically for distributed solar rooftops, residential PV systems, and off-grid PV applications. This solar combiner box combines two DC input strings into one single output to the inverter and provides all three functions of a DC breaker, surge protector, and wiring box in one pre-assembled, factory-tested enclosure.

The integrated 32A DC MCB provides overcurrent and manual isolation protection at DC-PV1 class & DC-PV2 class levels. The Type 2 DC SPD (40kA Imax) protects the inverter from induced surge voltages from lightning strikes nearby. The PC/ABS enclosure is rated IP65 for protection against ingress of water and dust, and IK10 for impact resistance, ensuring durability for long periods when installed outdoors. The DC combiner box is CE, TUV & CB certified and meets international standards for PV system protection. HUYU Electric offers OEM/ODM factory direct with private labeling and complete documentation for distributors and installers.

Technical Data – EXCB1-DC2-1

Consolidated Housing with Built-In Security

The PC/ABS housing is flame rated and UV resistant as well as having an IP65 rating for dust and low-pressure water jet protections which makes it suitable for wall mounting outside in exposed locations. The enclosure has an IK10 impact rating meaning that it can withstand a 20-joule mechanical impact (e.g., 5 kg mass dropped from 40 cm), providing lasting protection against incidental damage during installation or maintenance. The DC circuit breaker (rated DC-PV1/DC-PV2) within the housing provides string-level isolation and overcurrent protection, while fuses on each input add an additional layer of selective protection. All internal wiring is factory-assembled and tested prior to shipment, so the installer only connects the PV string cables and the inverter output.

OEM/ODM Manufacturing – Compact PV Combiner Boxes for Residential Solar Power Systems

Buyer’s Guide

How to Select a PV Combiner Box for Dual-String Residential Systems

Key selection criteria for the EXCB1-DC2-1 2 in 1 out combiner box in distributed PV applications.

1. When to Use a 2 In 1 Out Configuration

Select a 2-in-1-out PV combiner box when your system has two parallel DC strings feeding a single-MPPT inverter input. This is common in residential installations with two identical strings — for example, east-west split arrays, or two roof surfaces with the same module count. The combiner box provides individual fuse protection for each string and combines them into one output, eliminating the need for separate DC breakers and junction boxes.

2. Fuse Sizing for Individual Strings

Select the fuse rating based on 1.25 × Isc of the individual PV string. For most residential modules with Isc around 10A–11A, a 15A or 16A fuse is appropriate. For larger modules or bifacial panels with higher Isc, 20A or 25A fuses provide the necessary headroom. The EXCB1-DC2-1 supports optional fuses from 15A to 32A (Φ10×38mm), allowing precise matching to the string characteristics.

3. Surge Protection for Rooftop Installations

The integrated Type 2 SPD (40kA Imax) meets EN 50539-11 requirements for PV applications. For rooftop installations on residential buildings — where the DC cable run from the roof to the inverter can act as an antenna for induced surge voltages — this protection is essential. The SPD diverts surge current to ground before it reaches the inverter’s DC input stage.

4. Enclosure Durability for Outdoor Use

The EXCB1-DC2-1’s IP65 + IK10 PC/ABS enclosure is rated for outdoor wall mounting adjacent to the PV array. The UV-resistant material prevents degradation from sunlight exposure over the system’s 25-year lifespan. The IK10 impact rating provides protection against accidental mechanical damage during installation and routine maintenance. Install in a shaded location where possible to minimize internal temperature rise.

Frequently Asked Questions

What does a PV combiner box do?

A PV combiner box combines the DC output of multiple solar panel strings into a single DC feed to the inverter. It provides string-level overcurrent protection (via DC circuit breakers or fuses), surge protection (via DC SPD), and a clearly marked manual isolation point for maintenance and emergency shutdown. The EXCB1-DC2-1 PV combiner box 2 in 1 out handles two input strings with individual fuse protection, combining them into one output. This simplifies wiring, reduces the number of DC cables running to the inverter, and ensures that a fault in one string does not backfeed into the other.

What is the 33% rule in solar panels?

The “33% rule” is not a formal electrical code requirement but a practical guideline for sizing PV combiner box enclosures. It suggests that the internal wiring and components should not occupy more than 33% of the enclosure volume, leaving adequate space for heat dissipation and future maintenance access. The EXCB1-DC2-1 solar combiner box enclosure is designed with this practical margin, ensuring that the integrated DC MCB, SPD, fuses, and wiring have sufficient air volume for thermal management during continuous operation at rated current.

Why are people getting rid of their solar panels?

Some homeowners remove solar panels due to roof condition issues, system underperformance, or changes in feed-in tariff economics. However, a well-designed PV system with proper DC-side protection — including a quality DC combiner box — typically operates reliably for 20–25 years with minimal intervention. The most common technical reasons for premature panel removal are: DC arc faults caused by loose connections (prevented by regular torque checks at the combiner box), water ingress into poorly sealed enclosures (prevented by the EXCB1-DC2-1’s IP65 rating), and surge damage to inverters (prevented by the integrated Type 2 SPD). Investing in certified, well-constructed combiner box components at installation reduces the likelihood of system issues that could lead to early decommissioning.

How to connect a PV combiner box?

To connect a PV combiner box like the EXCB1-DC2-1, first mount the enclosure on a wall near the PV array using the provided brackets. Connect each PV string’s positive and negative cables to the corresponding input terminals — the EXCB1-DC2-1 has two Pg09 input ports for the two strings, accepting 2.5–4 mm² cable. Connect the output cable (4–6 mm²) to the Pg25 output port, running it to the inverter’s DC input. Ensure the DC isolator switch is in the OFF position during wiring. Connect the ground wire to the designated earth terminal. After all connections are torqued to specification, close the enclosure, switch the DC breaker to ON, and verify voltage at the output terminals. Installation must be performed by a licensed electrician in compliance with local electrical codes. Always follow the manufacturer’s wiring diagram and torque specifications.