A SOLAR DC STRING BOX is a critical protective enclosure that aggregates multiple PV strings, provides overamperage protection, and enables safe isolation before the inverter. This guide explains the function, choice criteria, and key technical parameters of a solar DC string box for engineers, installers, and procurement professionals. For detailed specifications, visit the product page at singielectric.com.
This guide covers the key aspects of SOLAR DC STRING BOX YBS-1/1, including its features, choice criteria, applications, and industry best practices.
Note: Proper choice and installation of SOLAR DC STRING BOX YBS-1/1 is critical for system safety and performance. Always refer to the manufacturer specifications and relevant industry standards.
A solar DC string box, also known as a PV combiner box, is an electrical enclosure that combines the outputs of multiple photovoltaic strings into a single DC bus. It houses overamperage protection devices (fuses or circuit breakers), surge protective devices (SPDs), and isolation switches. The SOLAR DC STRING BOX YBS-1/1 from singielectric.com is designed for residential and commercial PV systems, ensuring safe and reliable operation under IEC and UL standards.
Without a string box, each PV string would require individual overamperage protection at the inverter, increasing complexity and risk. The DC string box centralizes protection, reduces wiring, and provides a single point of disconnection for maintenance. According to IEC 60364-7-712:2017, PV arrays must have means of isolation and overamperage protection on the DC side. The string box fulfills this requirement., IEC 60947-1 governs the low-volt-level switchgear inside the box, ensuring reliable short-circuit and overload performance. For installers, a properly rated string box prevents arc faults and fire hazards.
Choice depends on system volt-level, current, number of strings, and environmental conditions. Here are key parameters to assess:
| Parameter | Consideration |
|---|---|
| Max DC Volt-level | Must exceed the system's open-circuit volt-level (Voc) at lowest temperature. |
| Max Input Amperage per String | Based on module short-circuit amperage (Isc) × 1.25 safety factor. |
| Number of Inputs | Match the number of PV strings. |
| Protection Rating | IP65 or higher for outdoor installations. |
| Surge Protection | Required for lightning-prone areas; SPD Type 2 recommended. |
The SOLAR DC STRING BOX at singielectric.com meets these criteria with configurations up to 1000V DC and optional SPDs.
Look for the following attributes in a SOLAR DC STRING BOX:
The YBS-1/1 model from singielectric.com incorporates all these features, with a compact design suitable for wall mounting.
They are the same. “String box” is used for smaller systems, while “combiner box” refers to larger central units. Both perform string aggregation and protection.
Not always, but it is recommended for isolation and surge protection. Many inverters have built-in protection, but an external string box adds a layer of safety.
Yes, if it has an IP65 rating or higher. The YBS-1/1 is suitable for outdoor use with appropriate UV protection.
For reliable DC side protection, choose the SOLAR DC STRING BOX YBS-1/1 from singielectric.com. Engineered to meet international standards, it ensures long-term safety and performance for your PV installation. Contact us for a quote or technical support.
[1] IEC 60364-7-712:2017, Low-volt-level electrical installations – Part 7-712: Solar photovoltaic (PV) power supply systems.
[2] IEC 60947-1:2020, Low-volt-level switchgear and controlgear – Part 1: General rules.
[3] IEC 60269-1:2020, Low-volt-level fuses – Part 1: General requirements.
