• string.CB AIO 24/12 (all-in-one solution)

string.CB AIO 24/12 (all-in-one solution)

Effective PV Monitoring requires constant, solid and traceable PV Plant monitoring data in order to determine actual performance and fulfil owner/investor expectations.
Operators are interested to identify errors and losses in a reliable way to trigger appropriate actions for maximizing energy harvest during the total system lifetime.
With the monitoring of PV Module strings, design and production errors will be recognized on the DC side with high resolution down to PV Module level.

Using DC shunts (vs. Hall Effect sensors) the string.bloxx provides current measurements typically 10 times more accurate and not susceptible to temperature variance. This equates to higher accuracy measurements and better understanding of true system performance. In addition, string voltage (up to 1500 V) and DC power on every string can be continuously monitored ensuring maximum system productivity.

Continuous measurement of both cabinet and panel temperatures, along with overvoltage monitoring and main switch control greatly and improves system diagnostics.

This accurate measurement is inverter independent and gives feedback about losses due to inverter malfunction, soiling, shading, PV Module degradation etc..

The main benefits of string.CB AIO 24/12:

  • Unifies DC measurement, fuses, overvoltage protection & communication leading to improved ROI
  • Cost reduction by 30% vs. standard concepts
  • Format Factor reduced by 35% with up to 312kWp DC power per Unit
  • Significant reduction of interfaces leads to reduced risk and faster plant installation time

Key features

Channels 24 Input Channel per board,
± 13 A String current, ± 312 A summary @ 60°C
Inputs for current measurement 12 Analog inputs for current measurement ± 26 A string current (calibrated)
Temperature sensor 1 On board temperature sensor cabinet temperature
VDC Layout On board 1000 VDC SPD (option 1500)
2 Digital inputs Monitoring of overvoltage protection and main switch
Signal conditioning Calculated DC power, linearization, mean value, scaling, alarm
RS485 fieldbus interface Up to 115.2 kbps: Modbus-RTU, ASCII (optional OEM protocols)
Connectivity Data logger (e. g. Q.reader) and gantner.webportal for worldwide access or other 3rd party applications

Functional Scheme


DC Input
Max. Number 24
Max. Current ± 13 A
Connection 0.25 mm2 - 6 mm2 push-in spring-cage connection
Max. DC Input voltage 1000 VDC
Nominal current of string fuses 15A (typical) or based on customer requirements; positive and negative side
Fuse dimensions 10x38 mm
Grounding terminal 35 mm2
Current measurement
Max. Number 12
Range ± 26 A
Accuracy 0.25 %
Voltage measurement
Number 1
Range 0-1000 VDC
Accuracy 0.2 %
Connection 0.25 mm2 - 6 mm2 push-in spring-cage connection
DC Output
Max. total current 312 A
Max. voltage 1000 VDC
Output terminal Cage clamp 50-240 mm2 or based on customer requirements
Max. cable dimensions SM 70-240 mm2, RM 50–185 mm2, RE 70-240 mm2
Input cabinet temperature
Number 1
Type Digital, onboard
Range -40 °C till +160 °C
Accuracy ±0.5K
Digital Inputs
Number 2
Utilization Supervision of main switch, DC over-voltage-protection
Power Supply
Power supply 10 up to 55 VDC, overvoltage and overload protection
Power consumption approx. 1.5 W (0.4W at 30 seconds sample rate)
Connection 0.2 mm2 - 2.5 mm2 push-in spring-cage connection
Communication Interface
Standard RS-485, 2-wire
Data format 8e1
Protocols Modbus-RTU: 19.200 bps (default), range: 9.600 bps up to 115.200 bps
Number of devices per bus 32 (recommended), max. 99
Connection 0.2 mm2 - 2.5 mm2 push-in spring-cage connection
Max. cable length 500 (recommended), max. 1200 m; expandable with active repeaters
Overvoltage protection PV section Overvoltage arrester 2 / II acc. to EN 61643-11 / IEC 61643-1/-11
Nominal surge current: (8/20) 20 kA with 3-stage DC- switch for PV Power Plants, up to 1000VDC
Overvoltage protection Communication (RS485) Gas Discharge Tube - GDTs / Gas-Plasma-arrester mini trigard symmetrical SMT;
Peak- impulse-current: 10 kA, 600 Watt Transient Voltage Suppressors
Protection class acc. to EN 6052 IP 66
Protection class acc. to EN 61140 Class II, double insulated protection
Operating temperature -20°C up to +60°C @ max 312 A current
Storage temperature -40°C up to +85°C
Relative humidity 5 % up to 95 % at 50°C, non-condensing
Height w/o mounting socket 847 mm
Width 636 mm
Depth 300 mm
Cable gland 49xM12, 2xM50, 2xM25
Weight 35 kg
Housing UV- and weatherproof, fiber glass reinforced polyester
(e.g. Schneider Electric); RAL 7035 (light gray)