A PV combiner box is used to combine multiple solar panel strings so they have a single output for controlling in and providing a way to protect the electrical currents that originate from these panels, hence improving safety in solar power systems. The combiner box is paramount in preventing overcurrent and fault isolation in high voltage systems—usually between 600 and 1,500 volts DC for commercial or utility scale. Inside, the connection between each string typically includes a 15-20 amp fuse to protect against high current that can cause excess heat and may even lead to electrical fires.
PV combiner boxes commonly feature surge protection devices (SPDs) to protect the equipment from surges resulting from lightning strikes or spikes in power on the grid. Even if these SPDs are designed to be able to handle surges up to 40 kA, that is where lightning is common at one specific location. Offering protection against system failure and enhancing the overall safety profile, when there is additional voltage due to outside conditions, it gets diverted to ground through the combiner box so no damage occurs within the solar inverters and other vital components.
Such as the tests for compliance with IEC standard and other standards developed by UL, etc., PV combiner boxes must comply with stringent safety and durability criteria set forth by the International Electrotechnical Commission (IEC) [4]. Many combiner boxes are IP65 rated or greater, which means they have total dust protection and will withstand low-pressure water jets used in outdoor installation where the elements might be present. Such a high level of protection means that the box can operate with safety and reliability for typically 25 years or more.
For instance, the quality of the PV combiner box can cause safety and efficiency issues in high-profile projects like utility-scale solar farms. For larger solar systems, the combiner box is described as “the first line of defense” against electrical faults by the National Renewable Energy Laboratory (NREL). A well-architected PV combiner box can help operators minimize risks, save on maintenance, and extend system life by mitigating voltage fluctuations from other strings to the extent that problematic strings get isolated before affecting the rest of the array.
Combined with regular inspection and maintenance of the same, PV Combiner Box ensures higher reliability making it a vital component present in comparison to other components in solar power systems when it comes to achieving high safety standards with maintaining the overall efficiency.