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PV Combiner Box for Solar Arrays | IP66 | 2-16 String Inputs | 600-1500V DC
KRIPAL Solar Combiner Box
KRIPAL manufactures PV combiner boxes in the UKCB series, pre-wired DC enclosures that consolidate multiple photovoltaic string inputs into a single DC output feeder for connection to the inverter. Available in configurations from 4 to 24 string inputs with a rated operational voltage up to 1500V DC, these combiner boxes integrate UKB7Z DC MCBs or UKRT18PV DC fuses per string input, a UKP3 DC main isolator switch, UKD2 DC surge protective devices and a string monitoring unit (SMU) for current measurement per string with Modbus RTU communication. The IP65 powder-coated steel or stainless steel 304 enclosure is UV-resistant and rated for outdoor installation in ambient temperatures from minus 25 to plus 60 degrees Celsius, with cable gland plates on the bottom face for DC string cable entry and a hinged front door with a lockable latch for security. Certified to IEC 61439-2 for low-voltage switchgear assemblies with a DC-PV specific verification of temperature rise and short-circuit withstand, KRIPAL UKCB combiner boxes are factory-wired and tested, reducing field installation time from days to hours compared to assembling individual components on site.
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Ask a QuotePV Combiner Box Selection: Pre-Engineered String Combining with Integrated Protection
A PV combiner box is a factory-assembled DC enclosure that takes multiple string inputs, protects each string with an overcurrent device (fuse or MCB), combines the strings onto a common DC busbar, provides surge protection for the combined output, and includes a main DC isolator for safe disconnection of the entire sub-array. IEC 62548 requires a means of isolating each PV string (which the string overcurrent device provides) and a means of isolating the entire array (the main isolator switch). A pre-wired combiner box integrates all these functions in a single enclosure, reducing field wiring points and the associated risk of loose connections causing DC arcing faults. This selection guide covers input count, string protection device type, monitoring options and enclosure material.
UKCB PV Combiner Box Series Technical Specifications
String Input Count and Busbar Configuration
UKCB combiner boxes are available in standard input counts of 4, 6, 8, 12, 16, 20 and 24 strings, with custom counts available on request. The internal DC busbar is a solid copper bar with tin-plating, sized for the maximum combined current of all string inputs operating at rated power. For a 16-string combiner box with each string rated at 11A Isc, the busbar is sized at 250A continuous with a short-circuit withstand of 25kA for 1 second. Each string input terminal accepts DC cable from 2.5 to 10 sq mm, while the main output terminals accept 50 to 150 sq mm DC cable depending on the total combined current. The busbar is supported on ceramic standoff insulators rated for 1500V DC plus a 20 percent safety margin.
String Protection Device Selection: Fuse vs MCB
UKCB combiner boxes offer a choice of string protection devices. The fuse configuration uses UKRT18PV gPV fuse-links in individual fuse bases with blown-fuse indicators, providing 30kA DC breaking capacity and the lowest cost per string. The MCB configuration uses UKB7Z DC MCBs with 6kA breaking capacity and the advantage of resettability after a transient fault is cleared, avoiding the need for a site visit to replace a blown fuse. For utility-scale PV plants with remote O&M access, the MCB configuration is preferred because a string that trips on a transient overcurrent (cloud-edge effect) can be remotely reset by cycling the inverter output without dispatching a technician. For small residential and commercial systems where a site visit is acceptable, the fuse configuration offers cost savings without compromising protection performance.
String Monitoring and Communication Options
The UKCB can be equipped with a string monitoring unit (SMU) that measures DC current per string using Hall-effect sensors on each string input conductor, with an accuracy of plus or minus 1 percent of reading. The SMU communicates via Modbus RTU over RS-485 to the plant SCADA or data logger, transmitting string current, combiner box internal temperature, SPD status and main isolator position every 15 seconds. An optional DC voltage measurement channel monitors the combined busbar voltage. This string-level monitoring enables early detection of underperforming strings (current 10 percent or more below the array average) caused by module soiling, shading from vegetation growth, or module degradation, allowing the O&M team to prioritize cleaning and maintenance visits based on actual string performance data rather than calendar-based schedules.
Enclosure Material and Environmental Protection
The UKCB enclosure is available in powder-coated galvanized steel (standard, suitable for most outdoor installations with a C4 corrosion class per ISO 12944) and stainless steel 304 (for coastal and high-corrosion environments with C5 corrosion class). The enclosure is IP65 rated with a foam-in-place polyurethane door gasket that maintains its sealing performance after 10,000 open-close cycles in accelerated testing. Cable entry is through a removable gland plate on the bottom face with pre-punched metric knockouts (M20, M25, M32) that accept standard PV cable glands. An internal condensation drain valve prevents water accumulation from the natural breathing cycle of the enclosure as internal air temperature changes between day and night. The enclosure includes a grounding busbar with multiple terminals for connecting the PV module frame grounding conductors.
Specify Your PV Combiner Box Configuration
- Configuration Worksheet: Complete our combiner box specification sheet with your string count, voltage, current and monitoring requirements for a priced proposal within 2 business days.
- Pre-FAT Inspection: Schedule a video-call factory inspection of your assembled combiner boxes before shipment, with live electrical testing witnessed remotely.
- Project Logistics: Combiner boxes are shipped on dedicated pallets with custom foam inserts to prevent component damage during ocean freight transit.
Pre-Engineered PV Combining for Residential to Utility-Scale Projects
KRIPAL UKCB PV combiner boxes are the central aggregation and protection point in photovoltaic DC distribution systems, installed between the PV array strings and the inverter DC input. From rooftop combiner boxes on commercial buildings to central recombiners in multi-megawatt solar farms, the factory-wired, tested and certified enclosure approach reduces field labor, improves reliability and provides a single point of isolation and monitoring for the DC sub-array.
Commercial Rooftop Solar Array String Aggregation
A 200 kW commercial rooftop installation with 500 PV modules arranged in 16 strings per inverter deploys two UKCB-8 combiner boxes on the roof, each consolidating 8 strings into a single DC feeder cable routed through the building to the inverter in the electrical room. The IP65 enclosure withstands rooftop exposure to rain, snow and direct sunlight, while the internal DC MCBs provide string-level overcurrent protection and the integrated SPD protects against induced lightning surges coupled onto the rooftop DC cables. The factory pre-wiring eliminates 64 field-made DC terminations (8 strings x 2 poles x 2 combiner boxes plus 8 terminations for the main output), reducing the electrical contractor’s rooftop labor by approximately 6 hours per combiner box.
Utility-Scale Ground-Mount Array Recombiner
In a 100 MW solar farm, UKCB-24 combiner boxes serve as array recombiners, aggregating 24 string inputs from one PV array block into a single DC output feeding the inverter DC bus. Each recombiner processes approximately 500 kW of DC power, with the main DC isolator providing the single-point disconnection for the entire array block during inverter maintenance. The string monitoring unit transmits per-string current data to the plant SCADA over a fiber-optic Modbus network, enabling the O&M provider to detect string-level underperformance within 15-minute intervals. When a string current drops 15 percent below the array block average, the SCADA generates an automated work order for a field technician to investigate the affected string for module soiling, vegetation shading or connector degradation.
Floating Solar PV Array Combiner Box
Floating PV installations on reservoirs and hydroelectric dam lakes deploy UKCB combiner boxes in stainless steel 304 enclosures mounted on floating platforms, with all cable entries sealed against water ingress from wave splash and condensation. The stainless steel enclosure withstands the high-humidity, high-corrosion environment above a body of water, where standard powder-coated steel enclosures would show rust within the first year. The internal DC components are conformally coated to prevent corrosion from the saline atmosphere in coastal floating PV installations, and the enclosure includes a pressure equalization breather vent that prevents water being drawn in through the cable glands during the cooling cycle as the enclosure internal pressure drops below atmospheric pressure.
Carport Solar Canopy Combiner Box
Solar carports at commercial office parks, shopping centers and airport parking facilities use UKCB-12 combiner boxes mounted on the carport structural columns, consolidating the strings from the canopy-mounted modules into a DC feeder cable routed underground to the inverter. The combiner box is installed at a height accessible from ground level for maintenance, with the lockable enclosure preventing unauthorized access in publicly accessible parking areas. The string MCBs allow individual strings to be isolated for module cleaning or replacement without shutting down the entire carport array, minimizing disruption to the building’s solar energy generation during daytime maintenance operations.
Agricultural PV (Agrivoltaic) Combiner Box
Agrivoltaic installations where solar panels are mounted above crops at an elevated height (3-5 meters) deploy UKCB combiner boxes on the array support structure, with a particular focus on protection against dust ingress from agricultural activities (plowing, harvesting) and ammonia corrosion from fertilizer application. The IP65 enclosure with the polyurethane gasket provides dust protection, and the stainless steel 304 option resists ammonia-induced stress corrosion cracking that affects standard galvanized steel enclosures in agricultural environments. The string monitoring unit helps the farm operator correlate PV production data with crop growth stages, informing decisions on panel tilt angle adjustment to optimize the balance between electricity generation and photosynthetically active radiation reaching the crops below.
Configure Your PV Combiner Box
- Specification Support: Our application engineers review your PV array layout and recommend the optimal combiner box placement, string count and protection configuration.
- Factory Acceptance Test: We test every combiner box at full rated voltage and current on our DC test bay, with a test report compiled per unit serial number.
- OEM Partnerships: Integrate UKCB combiner boxes into your PV system offering with your branding, custom component selection and dedicated production scheduling.
KRIPAL PV Combiner Box Manufacturing: Pre-Assembled and Factory Tested
KRIPAL PV combiner boxes are manufactured in a dedicated panel-building workshop where IP66 enclosures are machined for cable gland entry, DC busbars are fabricated from tinned copper, and SPDs, fuse holders, and DC isolators are mounted and wired to customer configuration. Every box undergoes a point-to-point wiring continuity test before shipment to global solar farm EPC contractors.
Enclosure Machining and IP66 Integrity Verification
Sheet steel and polycarbonate enclosures are CNC-machined for cable gland cutouts, mounting plate drilling, and ventilation grille installation. Each enclosure undergoes an IP66 water jet test after machining to verify that the modified enclosure retains full ingress protection before component installation begins.
Tinned Copper DC Busbar Fabrication
DC busbar systems are fabricated from high-conductivity electrolytic copper bar stock (IACS 98 percent minimum), cut to length, punched for terminal positions, and electroplated with tin for corrosion resistance. Busbar cross-section is sized for the specified string current at 125 percent rating per IEC 61439-2 with temperature rise verified on the first article of each design.
String-Level Monitoring Integration
Combiner boxes configured with string current monitoring incorporate Hall-effect current sensors or shunt-based measurement modules wired to a data logger interface. Each sensor channel is calibrated against a reference current source across the 0 to 20A measurement range, with accuracy verified within plus or minus 1 percent of full scale.
Point-to-Point Wiring Continuity and Polarity Test
Every completed combiner box undergoes a 100 percent wiring test: each string input to busbar connection is verified for continuity and correct polarity, DC SPD connections are confirmed, and the DC isolator is operated through all positions with verification of auxiliary contact switching. Test results are recorded against the serial number.
Distributor Stock Holding Programs for PV Combiner Boxes
KRIPAL supports distributor inventory programs with agreed stock levels for standard PV combiner box configurations. Shipments are planned based on demand data, with scheduled replenishment to maintain stable supply and consistent fill rates.
Private Label and OEM Branding for PV Combiner Boxes
Custom nameplates with your project branding, OEM-labeled enclosure doors, and customized wiring schedules and test reports are available. Unbranded supply is provided upon request for private label production of PV combiner boxes.
Multi-Region Certification and Compliance Support
CE, UKCA, and IEC 61439-2 EN 61439-2 compliance documentation is provided according to target export markets. Technical documentation files are maintained and updated in line with evolving regulatory requirements, supporting solar farm power collection system conformity assessments.
Direct Technical Access to KRIPAL Production Engineers
Your technical team communicates with the engineers who designed and wired your PV combiner boxes, not a distributor’s sales engineer reading from a catalog. Application questions receive answers within 24 hours during China business hours.
Frequently Asked Questions
Explore FAQ >A PV combiner box connects multiple parallel PV strings into a single DC output, reducing cable runs to the inverter while providing centralized overcurrent, surge and isolation protection per IEC 61439-2.
Select a box with inputs equal to your parallel string count plus 2 spare positions. For a 10-string array, choose a 12-string combiner box for future expansion.
DC MCBs are resettable but cost more. DC fuses are lower cost per string but must be replaced after operation. For residential, MCBs offer convenience. For utility-scale, fuses provide cost-effective per-string protection.
Yes. KRIPAL combiner boxes use IP66 UV-stabilized polycarbonate enclosures designed for direct outdoor mounting adjacent to the PV array with no additional shelter required.
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