Q3 Energie showcased a new string combiner box at Intersolar Europe 2025. The generator junction box can detect and isolate faults in photovoltaic systems.
From pv magazine Germany
In ground-mounted PV plants with central inverters, a fault in a single string can shut down the entire system. High failure rates and complex diagnostic processes make troubleshooting time-consuming and costly, increasing operating costs.
Germany-based Q3 Energie GmbH has developed a generator junction box, or string combiner box, to address these issues. The company said the device can locate and isolate faults in a single string, allowing operators to shut down only the affected string while keeping the rest of the system online to maintain overall availability.
The “Q3 Super Multi Box” is a generator junction box built for ground-mounted PV systems. Key features include individual string current measurement for up to 24 inputs and electronic DC isolation capability for up to 480 A at 1,500 V (DC).
In the event of a fault, such as an arc or insulation issue, the system first disconnects all strings to protect the installation. It then reconnects them step by step, identifying the exact string where the fault occurred. The system isolates the affected string while allowing the others to continue operating. This function enables precise troubleshooting, maintains system availability, and supports targeted service planning, which helps cut operating costs.
The box includes an integrated fault manager that supports remote maintenance. Type 1 and 2 surge protection with remote signaling contact adds protection against lightning strikes and voltage spikes. The Q3 Super Multi Box also features fuses on the positive pole and, optionally, on the negative pole, rated at 32 A at 1,500 V (DC).
For communication, the box uses multiple interfaces, including Modbus TCP/IP, RS485, Ethernet, and USB. MC4 EVO2 connectors secure the power inputs, enabling simple and reliable connections. Solar power drives the electronics, while an integrated battery maintains communication capability at night. With an IP66 rating, the system resists dust and water, making it suitable for outdoor use.
Q3 Energie will begin series production of the Q3 Super Multi Box in the third quarter of 2025. Project-specific planning and quotations are already available. The company also plans to collaborate with central inverter manufacturers to enhance system integration and optimization.