String Monitoring Unit (SMU)

The SMUs offered by Sumai are designed to ensure increase in overall return on instrument for PV system installation, while increasing safety for O&M employees, especially for MW scale projects. The following sub-components ensure accurate measurement of various factors to better understand the system performance:

  • DC Fuse
  • DC shunts (Hall effect sensors)
  • String card
  • Connectivity to PLC/SCADA via MODBUS/RTUn

Technical parameters

Technical Data
Input DC
Max. input voltage 1000VDC
Maximum current per string 15Amp
Number of measuring channels 6/10/16/24
Nominal string fuse current Optional up to 30A(10/12/15/20/25/30)
No. of DC input(+ve and –ve) 6/10/16/24
String cable connection Polyamide cable gland/MC4 Connector
Cable entry Bottom
DC switch rating 160/200/320Amp
Monitoring devise power source Auxiliary power supply/I Built(AC-DC Converter)
Surge protection Type-2
Output DC
Max .output current Up to 250
DC output cable size Up to 300amp
DC output cable exit Polyamide gland/brass
Number of DC outputs 2
Monitoring Devise
Measuring parameters Input current, system voltage, internal temperature
Type of monitoring Shunt
On board temperature measuring range 0-120c
Communication Modbus RS485 2 Wire 2 x 2c twisted pair shielded 0.5 SQMM RS485 standard
Protocols Modbus –RTU: 19.200bps(default),range : 9.600bps up to 115.200bps
MODBUS ID Defined by DIP
Data recording PLC/SCADA
Digital Ports 2
Analog Ports 1
Voltage measurement accuracy (+/-)0.2%
Current measurement accuracy <1%>
General Data
Encloser Material Polycarbonate /FRP
Degree of protectionDegree of protection IP 65
Mounting type Wall mounted/structure mounted
Operating temperature -10c to +60c@max312 a current
Relative humidity 5% up to 95%