Ground-mounted photovoltaic (PV) plants using central inverters often face a critical challenge: a fault in a single string can trigger a shutdown of the entire system. This results in high failure rates and complicated diagnostics, increasing operational downtime and costs.
Addressing this issue, Germany-based Q3 Energie GmbH has developed the Q3 Super Multi Box, a generator junction box designed to enhance fault detection and isolation in ground-mounted PV systems. The device allows operators to pinpoint and isolate faults in individual strings, enabling only the affected string to be shut down while maintaining operation of the remaining system.
The Q3 Super Multi Box supports up to 24 string inputs, each with individual current measurement capabilities. It offers electronic DC isolation for currents up to 480 A at 1,500 V (DC), providing robust protection for the entire installation.
In case of faults such as arcs or insulation failures, the system initially disconnects all strings for safety, then sequentially reconnects them to identify the faulty string. By isolating only the problematic string, the solution ensures continued system availability and enables precise, targeted maintenance, reducing operating costs.
Equipped with an integrated fault manager, the device supports remote diagnostics and maintenance. It includes Type 1 and 2 surge protection with remote signaling contacts to guard against lightning and voltage spikes. Fuses on the positive pole—and optionally on the negative pole—are rated at 32 A at 1,500 V (DC).
Communication is facilitated via multiple interfaces including Modbus TCP/IP, RS485, Ethernet, and USB. Power inputs are secured with MC4 EVO2 connectors for reliable connections. Solar power supplies the electronics, while an integrated battery maintains communication during nighttime. The box’s IP66 rating guarantees dust and water resistance for outdoor installations.
Q3 Energie plans to commence series production of the Q3 Super Multi Box in Q3 2025. The company is already offering project-specific planning and quotes, and aims to collaborate with central inverter manufacturers to improve integration and system performance.
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