EXCB3-DC2-2 2 In 2 Out Combiner Box

EXCB3-DC2-2 2 in 2 Out Combiner Box – Dual MPPT Manual Isolation

The EXCB3-DC2-2, 2×2 Combiner Box from HUYU Electric was designed for those who use photovoltaic installations with an independent DC output. No breaker is present; however, each channel has its own DC isolator switch to create an open circuit for easier and safer maintenance. The EXCB3-DC2-2 is intended for systems with separate MPPT inverters and/or split arrays and combines two strings of input into two different output loads, with an isolator and optional fuse on each output load. The unit has (2) 40kA Type 2 SPDs to protect from AC & DC surge transient voltages in a single, compact IP65 IK10 enclosure.

This DC isolator combiner is perfect for residential or commercial solar installations requiring independent control of their outputs. By isolating each MPPT channel, the EXCB3-DC2-2 maximizes inverter performance while providing a central lockable disconnect switch. The EXCB3-DC2-2 was designed to meet CE, TUV, and CB certification standards to fulfill worldwide safety requirements. HUYU Electric provides factory direct OEM/ODM services to include custom branding architecture, making this solution attractive to solar distributors and installers looking for reliable pre-wired solutions.

EXCB3-DC 2-2 – Technical Data

Independent Protection of Dual MPPT and Split Arrays

Modern inverters are designed to accommodate multiple maximum power point tracking (MPPT) inputs, optimizing energy capture from PV strings installed in varying conditions. The EXCB3-DC2-2 facilitates this setup by integrating dual input/output isolated channels into a single safety hub. Each input string links to its own DC isolator and output channel, ensuring system independence for maintenance and fault handling. Enhanced protection against transient surges is provided by shared Type 2 SPDs, while optional individual string fuses offer targeted overcurrent protection. Its factory pre-wired construction significantly minimizes on-site installation time and reduces wiring errors.

OEM/ODM Supply – Dual Output Isolator Boxes for Safety-Critical PV

Buyer’s Guide

How to Select a 2 In 2 Out Combiner Box with DC Isolators

Key points for specifying the EXCB3-DC2-2 in dual MPPT PV systems.

1. Isolator vs. Breaker: Which Is Right for Your Project?

Choose the EXCB3-DC2-2 isolator combiner box when your local electrical code requires a visible, lockable disconnect on the DC side, or when you simply prefer the safety of a manual break. DC isolators do not trip automatically on overload — that function is handled by the optional fuses. This setup gives you precise control over disconnection during maintenance and is often favored in fire safety regulations.

2. Sizing Fuses for Each String

Each input channel can be fitted with an optional 15A–32A DC fuse. Select a fuse rated at 1.25 × Isc of the PV string. For a typical 10A Isc string, a 15A fuse is appropriate. The independent fuse per string means that if one fuse blows, the other string continues operating, which is a key advantage of this dual-output configuration.

3. Matching to a Dual MPPT Inverter

Connect each output of the EXCB3-DC2-2 to one MPPT input on the inverter. This preserves the independent maximum power point tracking that dual MPPT inverters are designed for. The 32A rated current per output comfortably handles most residential and small commercial string configurations. Verify that the total voltage of each string does not exceed 1000V DC.

4. Outdoor Installation Tips

Wall-mount the box vertically, close to the PV array but in a location that is easily accessible for operation and maintenance. The IP65 rating ensures protection against dust and water jets, but cable glands should face downward to prevent water accumulation. The IK10 impact resistance protects the enclosure from accidental mechanical damage during installation and service.

Frequently Asked Questions

What is a 2 in 2 out DC combiner box?

A 2 in 2 out DC combiner box takes two separate PV string inputs and provides two individually protected DC outputs — typically for connection to a dual MPPT inverter. The EXCB3-DC2-2 achieves this using manual DC isolator switches for each channel instead of circuit breakers. This provides a visible, lockable disconnection point for each string and keeps the electrical paths independent, which maximizes the inverter’s ability to optimize each string separately.

Why use a DC isolator instead of a circuit breaker in a combiner box?

A DC isolator switch provides a visible break in the circuit, which is a requirement in many electrical codes for safe maintenance and firefighter access. Unlike a circuit breaker, it does not trip automatically — it is a manual disconnecting device. In the EXCB3-DC2-2, overcurrent protection is still provided by optional DC fuses. This combination of isolator and fuse meets the need for both active protection and a secure, lockable isolation point.

Can I use a 2 in 2 out combiner box for a single inverter with one MPPT?

Yes, you can. While the EXCB3-DC2-2 2 in 2 out combiner box with isolators is optimized for dual MPPT systems, you can also connect both outputs to a single MPPT inverter input by combining them externally or using an adapter. However, for a single-string or single-MPPT setup, a 1-in-1-out or 2-in-1-out box might be more cost-effective. The 2-in-2-out configuration is specifically beneficial when you need to maintain separate electrical paths for two independent inverter inputs.

How do I install and wire the EXCB3-DC2-2 combiner box?

Installation is straightforward: wall-mount the enclosure near the PV array with cable glands facing down. Ensure all DC isolators are in the OFF position. Feed each PV string cable through the Pg09 input glands (2.5–4 mm²) and connect to the dedicated input terminals. Run the two output cables (4–6 mm²) through the Pg25 glands to the inverter MPPT inputs. Connect the ground wire to the earth terminal. After double-checking all connections, close the enclosure securely and turn the isolators ON. Always follow the wiring diagram supplied with the unit and comply with local electrical regulations. Installation must be performed by a qualified electrician.