EXCB1-DC4-2 Solar Combiner Box 4 In 2 Out

EXCB1-DC4-2 4 In 2 Out Solar Combiner Box – Optimized for Dual MPPT Systems

The EXCB1-DC4-2 is a great way to combine the power from up to 4 strings of solar panels into 2 separate outputs (each output is protected by its own 32A DC MCB) and is designed for use with dual MPPT inverter systems or for split-array projects by allowing you to independently manage 2 different groups of strings in a compact footprint. The Type 2 surge protective device (40kA Imax) that comes standard with the EXCB1-DC4-2 provides protection against lightning-induced transients on both output circuits.

The EXCB1-DC4-2 has received certifications from CE, TUV and CB. It meets all international safety standards. It is constructed from IP65 and IK10-rated durable PC/ABS materials and is designed for exterior wall mounting. With pre-wired configurations ready for installation, installers will save time on-site and have a product that they will recommend to others. HUYU Electric provides factory direct OEM/ODM service with private label products and complete compliance documentation to distributors and OEMs worldwide.

Technical Specifications – EXCB1-DC4-2

The DC4-2 model of the EXCB1 series can monitor two independent inverter MPPT inputs from a single enclosure. The installation process is streamlined for some split-array installations (relationship between roof installation and number of panels installed) – such as four panels in an east side and four panels in a west side of a roof – using two groups of two strings each. Each string (two strings) has a 32A MCB providing the necessary overcurrent protection (resettable) for that string, and the Type 2 SPD (Surge Protective Device) provides protection from surges to the entire system.

Efficient Dual MPPT Wiring

When utilizing PV systems with dual MPPT inverter technology, the EXCB1-DC4-2 4 String / 2 Output solar combiner box is a cleaner and more efficient method as opposed to using two separate 2-string combiner boxes. By combining protection and switching for four separate strings into one tidy box, you reduce the amount of wall space required and mounting brackets to install. By wiring both separate outputs to each MPPT input, you can continue to optimize the harvesting of energy for each section of array regardless of orientation or shading issues associated with that specific string. Using a pre-wired product that has all input and output terminals clearly marked makes installation easier and reduces wiring mistakes.

OEM/ODM Supply – 4-String Combiner Boxes for Dual MPPT PV Systems

Buyer’s Guides

How to Choose a 4-String Combiner Box for a Dual MPPT Inverter

Flexible criteria for choosing the EXCB1-DC4-2 combiners when working with split-array solar systems.

1. Inverter Topology Compatibility

The 4-string combiner box was engineered for use with inverters that have 2 independent MPPT inputs (i.e., for connecting 2 parallel strings to MPPT 1 and 2 parallel strings to MPPT 2). This means that every string’s voltage and current are optimized independently of the other strings in their respective arrays. If your inverter has a single MPPT input, you should choose either a 4-in-1-out combiner or an alternative type of combiner configuration.

2. Circuit Breaker Type Protection Method

The EXCB1-DC4-2 has individual resettable DC MCBs for each input string. These circuit breakers will protect each input string from overcurrent and short-circuit conditions automatically. You can safely isolate the string requiring maintenance by manually switching off the corresponding circuit breaker. If your local building code requires a visible isolation gap when maintaining a circuit, you may want to choose a model in the EXCB3 line of products since they utilize DC isolator switches in place of DC-MCBs.

3. Current and Voltage Headroom

Each input and output channel in the EXCB1-DC4-2 is rated for a maximum of 32A. You must also verify that the short-circuit current (Isc) rating of the solar panels you are using, when multiplied by the 1.25 safety factor, does not exceed 32A. The maximum voltage rating of the EXCB1-DC4-2 is 1000V DC; therefore, you will also need to verify that the open-circuit voltage (Voc) of your solar panels will always be below 1000V DC, at the coldest temperatures that your location experiences. The above ratings comfortably accommodate the vast majority of both 60-cell and 72-cell residential PV modules.

4. Type 2 Surge Protection for Multiple Strings

The 1000V Type 2 SPD listed herein provides surge protection for both output circuits from the combiner and serves as a single point of surge protection for each output circuit. Utilizing one surge protective device (SPD) to protect both output circuits from surges is much more efficient than installing two SPDs, one for each MPPT input. Additionally, the SPD is wired in parallel to the output circuits and safely diverts the surge energy to ground, thus protecting the sensitive DC inputs on the inverter.

Frequently Asked Questions

Is a solar combiner box necessary for a 4-string PV system?

Yes, a solar combiner box is essential for a 4-string PV system. Without it, you would have to connect four strings directly to the inverter, which may lack sufficient inputs or individual string protection. The EXCB1-DC4-2 4 in 2 out solar combiner box provides a centralized point for overcurrent protection, surge protection, and manual disconnection for all four strings, ensuring a safe, organized, and code-compliant installation.

Does a solar combiner box increase the voltage?

No, a solar combiner box does not increase the voltage. It combines multiple string inputs in parallel. When you connect strings in parallel, the voltage remains the same as a single string, while the total current is the sum of the currents of all the strings. For example, if you have two strings each producing 400V at 10A, the combined output will be 400V at 20A. Voltage is only increased by connecting components in series.

What does a combiner box do for solar panels?

A combiner box for solar panels acts as a central DC hub that merges the outputs of multiple solar strings. It provides three critical functions: overcurrent protection for each string via DC breakers or fuses, surge protection to shield the inverter from lightning strikes, and a manual disconnect switch for safe maintenance. The EXCB1-DC4-2 breaker type solar combiner performs all these tasks, while its 4-in-2-out configuration allows it to feed two independent inverter MPPT inputs for optimized energy harvest.

What is the difference between a 4-in-1-out and a 4-in-2-out combiner box?

The key difference lies in the output configuration. A 4-in-1-out solar combiner box combines all four strings into a single output, suitable for a single-MPPT inverter. A 4-in-2-out combiner like the EXCB1-DC4-2 splits the four inputs into two separate output groups. This is specifically designed for dual MPPT inverters, allowing each group of strings to be optimized independently. Using a 4-in-1-out box with a dual MPPT inverter would require external combining of the MPPT inputs, wasting the inverter’s dual tracking capability and potentially reducing energy yield.