Launched for the UK market at the Solar Energy UK 2013 exhibition, Bussmann’s new fully customisable combiner box range introduces new standards in protection, switching and monitoring of PV systems. Designed for system voltages from 600V DC to 1,000V DC, Eaton’s business’ new line offers the latest in overcurrent, overvoltage and monitoring technology.
With a capacity of up to 24 input strings the combiner box can accommodate a wide range of input currents using PV specific gPV fuses in ratings of 1-20A in 10x38mm fuses and 25-32A ratings in 14x51mm fuses. Each fuse is housed in a gPV rated fuse holder with the 10x38mm modular fuse holders benefiting from optional fuse indication. Mindful of the high ambient temperatures experienced by PV installations the fuse holders are spaced to allow good airflow and dissipate excess heat.
The type of PV installation design will influence the fuse protection configuration. Both positive and negative fusing for maximum system protection is recommended, with the new range offering floating ground as standard with the option of negative or positive only fusing if required.
To combat overvoltages and surges from direct and indirect lightning strikes the fitting of the minimum of a Class II PV surge protection device (SPD) is recommended; however, in some instances the fitting of a Class I device may be necessary. Where PV system monitoring is selected, additional protection of the 240V AC mains supply and Modbus wired communication lines may be required to safeguard the monitoring electronics from voltage surges.
Checking the status of the PV and 240V SPDs’ health is achieved with the inclusion of remote indication that integrates with the combiner box monitoring system. The replacement of activated surge devices is updated with the easyID visual indication and plug and play modular design.
Effective monitoring of the PV installation is a critical requirement in managing the system uptime, maximising productivity and efficiency. The monitoring system has a number of options depending on the system requirements, as well as power supply options such as self-powered or externally powered. Integration with the PV installation supervisory control and data acquisition (SCADA) system is made seamless with the use of industry standard Modbus communication protocols and the choice of standard 2-wire RS485 connection, or the option for wireless communication.
For additional safety and security the range features true DC rated disconnect switches to ensure safety and reliability. The switch can be operated repeatedly without the risk of fire or injury. By locating the switch handle on the outside the combiner box can be safely disconnected from the downstream load before maintenance work is carried out. The lockout feature of the switch handle also ensures safe PV system isolation for maintenance of downstream components. In the event the combiner box is used in configurations with a downstream disconnect, it can be supplied without a switch.
Finally the enclosure plays a critical part in securely housing and protecting the internal components. As standard Glass Reinforced Polyester or Polycarbonate enclosures are used, rated to IP65 and including breather drains making them suitable for the typical British environment; there are also options for IP54 and plinths accommodating a wide range of system configurations.
