EXCB3-DC1-1 1 String PV Combiner Box

EXCB3-DC1-1 1 String PV Combiner Box – Stand-Alone Isolation for Single Channel Inverter Applications with Manual Switching Capability

HUYU Electric’s EXCB3-DC1-1 1-string photovoltaic (PV) combiner box offers a unique electrical isolation solution using isolator, instead of circuit breakers, for the single channel PV installation. The isolator allows electrical contractors and service technicians to determine a clear point of electrical disconnection, while only using DC isolator switches as inputs, instead of breakers, on each PV string to the combiner box. The combiner box is designed with durable materials, IP65-rated, UV-resistant enclosure, that houses a type 2 surge protector (40kA Imax), and optional 15-32A DC fuses, to provide surge protection and overcurrent protection to the inverter power input. The EXCB3-DC1-1 is rated up to 32A input and 1000Vdc output to provide electrical isolation for residential solar systems with a single channel (MPPT) inverter.

Additionally, the integrated manual isolator, combined with Type 2 conforms to many local electrical code visible isolation requirements, thereby providing electrical isolation in accordance with industry standards and codes. Moreover, this pre-wired design will allow for the ease of installation by requiring the only connections of the PV string cable and the inverter output at the installation site; thus minimizing wiring mistakes and time expenditures associated with sizing and/or installing wires. Furthermore, the EXCB3-DC1-1 has obtained CE, TUV, and CB certifications and is appropriate for all global markets. Finally, HUYU Electric offers all residential solar distributors and/or OEMs, factory direct custom designs and branding services.

Technical Specifications – EXCB3-DC1-1

Why Choose Dedicated 1 String Combiner with Isolator?

For many residential photovoltaic systems, a single string is entirely sufficient. Opting for a larger multi-string combiner box often ends up wasting space and resources for unused circuits. The EXCB3-DC1-1 is ideally designed for such setups. Its manual DC isolator offers a lockable disconnection point, fulfilling the “visible isolation” requirement of multiple regional wiring codes. Additionally, the built-in surge protection serves to safeguard inverters against damage from voltage spikes.

This product provides optional DC fuses to enhance overcurrent protection, making it a highly functional and compact unit for residential solar installations. Furthermore, it requires minimum configuration and allows for quick installation with pre-assembled components.

OEM/ODM Supply – Single String PV Combiner Boxes for Your Solar Brand

Buyer’s Guide

Choosing the Best Combiner Box for a Single PV String in a Residential Setting

Key Factors to Consider When Specifying the EXCB3-DC1-1 in Residential PV Systems.

1. When Only One String is Necessary

Many residential solar power systems utilize one alternating current photovoltaic system by way of an array of panels supplying the electricity into that panel, which also acts as the source of energy for the entire home (or business). In those scenarios, a one string combined circuit, such as EXCB3-DC1-1, is the perfect solution as it prevents electrical surges and provides necessary isolation. It also combines the essential protective components in one enclosure without adding the cost or size of a larger unit. If a system is later expanded, an additional single-string combiner can be added.

2. Making a Choice Between an Isolator or Breaker

The EXCB3 series utilizes a manual DC isolator switch while certain other models offer DC breakers. If a visible isolation gap is required by your local code or if a manual disconnection is preferred for maintenance purposes, the EXCB3-DC1-1 is the recommended choice. Its lockable handle ensures the circuit stays off during servicing. The optional DC fuse further enhances overcurrent protection within the box.

3. Choosing the Correct Fuse Size

For added overcurrent protection, select a DC fuse with a rating of 1.25 times the short-circuit current (Isc) of the system’s PV string. For instance, a 10A Isc panel would require a 15A-rated fuse. The EXCB3-DC1-1 accommodates standard Φ10 × 38mm fuses ranging from 15A to 32A. While some inverters include built-in string fuses, these external fuses function as an accessible point for added safety measures close to the PV array.

4. Mounting and Environmental Considerations

Mount the enclosure vertically on a wall near the PV array, with its cable glands positioned downward to maintain the IP65 protection rating. The unit’s UV-resistant material ensures its durability under prolonged sunlight exposure. Although it is built to perform in harsh conditions (-20°C to +60°C), keeping it out of direct midday sunlight is recommended for extending its service life.

Frequently Asked Questions

What is the purpose of the string combiner box?

A string combiner box, such as the EXCB3-DC1-1 1 string PV combiner box, serves as a centralized protection and isolation point for the DC wiring from the solar panels to the inverter. Its purpose is to house surge protection, provide a manual disconnect switch for safe maintenance, and optionally hold fuses for overcurrent protection. By consolidating these functions in a weatherproof enclosure, it simplifies installation, improves system safety, and ensures compliance with electrical codes.

How many solar panels can I have on one string?

The number of panels on one string depends on the inverter’s maximum DC input voltage and the panels’ open-circuit voltage (Voc). You sum the Voc of all panels in series and ensure this total, corrected for the coldest expected temperature, does not exceed the inverter’s maximum input voltage or the combiner box’s voltage rating (e.g., 1000V). The EXCB3-DC1-1’s 32A current rating and 1000V voltage rating accommodate many common residential string configurations. Consult your inverter and panel datasheets for the exact limit.

What does a PV combiner box do?

A PV combiner box consolidates the DC output from one or multiple solar panel strings, provides overcurrent and surge protection, and offers a manual disconnection point. In a single-string application, the EXCB3-DC1-1 1 string solar combiner box with its integrated DC isolator ensures that the entire DC circuit can be safely de-energized for maintenance or in an emergency, while the Type 2 SPD protects the inverter from voltage surges caused by nearby lightning strikes.

What is the 120 rule for solar panels?

The “120% rule” applies to the AC side of a solar installation, specifically to the busbar rating in a load center when a backfed breaker is used. It requires that the sum of the main breaker rating and the solar backfeed breaker rating does not exceed 120% of the busbar’s ampacity. This rule does not apply to the DC side, where the EXCB3-DC1-1 PV combiner box operates. On the DC side, protection is sized based on string short-circuit current (Isc × 1.25) and system voltage, making the 120% rule irrelevant for combiner box selection.