SecSun UBM1101L PV Combiner Box AC/DC 3kW 1 String
The SecSun UBM1101L is an AC/DC combiner box (string box) for single-phase photovoltaic systems up to 3 kW, 1 string: integrated DC and AC disconnectors, surge arresters and RCBO. IP65, class II, EN 61439 compliant.
The SecSun UBM1101L is a pre-wired AC/DC combiner box (string box) for single-phase photovoltaic systems up to 3 kW with 1 string. It groups into a single IP65 enclosure all the protections required between the PV modules, the inverter and the domestic grid: disconnection, overcurrent and surge protection on both the DC and AC sides.
What is the UBM1101L for?
Between the string and the inverter, and between the inverter and the grid, the system needs disconnection points and protection against overvoltage and fault currents. The UBM1101L brings these devices together in one wall-mounted box, already wired and certified to CEI EN 61439-1/2, so the installer does not have to assemble the protections one by one on site.
Technical specifications
| Model | SecSun UBM1101L |
| Configuration | Single-phase, 3 kW, 1 string |
| DC side | 2P fuse-holder disconnector with 16 A / 1000 VDC fuses; 600 VDC surge arrester; 16 A / 600 VDC load-break switch |
| AC side | 1P+N 20 A 6 kA 300 mA class A RCBO; single-phase class II surge arrester Imax 20 kA |
| Protection rating | IP65, insulation class II |
| Standard | CEI EN 61439-1/2 declaration of conformity |
| Dimensions | 340 × 432 × 161 mm (W×H×D) |
Frequently asked questions
What is a combiner box for in a PV system?
It concentrates the disconnection and protection devices between modules, inverter and grid in a single certified enclosure: DC and AC disconnectors, fuses, and surge arresters. It protects the equipment and makes maintenance safer, allowing the system to be isolated at a single point.
Is the UBM1101L suitable for my system?
It is sized for single-phase systems up to 3 kW with 1 string. Check that your inverter and string match these values (voltage, current, number of strings) before ordering; for higher power or more strings, other models in the UBM range are available.
Can it be installed outdoors?
Yes. The IP65 rating protects against dust and water jets, so the box can be installed outdoors or in a technical room. Protection from direct sunlight and extreme temperatures is still recommended for a longer service life.
Who should install it?
Installation and connection must be carried out by a qualified electrician, respecting the polarities, tightening torques and the applicable regulations. The box is pre-wired, but the field connections and commissioning require professional work.
