Unity for Solar platform consists of the following components:

  • Unity Control Center (CC) : Operator platform for data storage, processing  and visualization of the monitored solar plants
  • Solar Plant Subsystem (SPS) : all peripheral monitoring and supervising devices such as controllers, sensors, and actuators installed at each solar plant

Solar Plant Subsystem

The Solar Plant Subsystem includes the Main Substation Unit, Peripheral Substation Units , String Combiner Boxes.

Main Substation Unit – MSSU

The MSSU is the heart of the Solar Plant Subsystem, installed in the main substation. It is connected to a variety of equipment that measure, monitor and control any desired parameter to networked intelligent devices along with various sensors and actuators. In detail:

  • It gathers all necessary data, pre-processes and forwards the results over a network connection to the centralized Control Center servers.
  • It may optionally undertake tasks relevant to the handling of the IP connection.
  • It integrates with the alarm system to collect security events.

The MSSU is a modular system built around an embedded processor and various I/O units consisting of:

  • An industrial computer based on a x86 or ARM processor
  • An available number of I/O units that offer dedicated connectors to terminate I/O channels from the plant
  • Interfaces that include analogue inputs and outputs, digital inputs and outputs, pulse inputs, serial and Ethernet interfaces


PSSU_webPeripheral Substation Unit – PSSU

A PSSU is optionally installed in each peripheral substation or inverter skid to extend the monitored signals. In detail:

  • Just like the MSSU, the PSSU can be connected to a variety of measuring, monitoring and controlling equipment as well as various sensors and actuators.
  • Together with the MSSU, the PSSU gathers all necessary data and  pre-processes and forwards the results over the network connection to the centralized Control Center.


String Combiner Box – SCB

The Inaccess SCB monitors each individual string so as to achieve the best possible yield of the solar plant. The SCB is designed to be used in solar plants with central inverters in order to monitor and pin point malfunctions at photovoltaic string level. In addition, the SCB offers fused DC inputs, an output switch, SPDs and electronic equipment for string current monitoring. Main features include:



  • Combines 8, 12, 16 or 24 PV strings
  • Up to 1000V DC in measurement side
  • Integrated DC load disconnector
  • Integrated surge protection with monitored state
  • 0-13.7A channel measurement range
  • 1KHz sampling with on-board averaging
  • Internal temperature measurement
  • MODBUS over RS485 communication
  • IP66 rated polycarbonate enclosure




Control Center

Unity Control Center is a centralized system that monitors and controls all solar plant subsystems. In the Control Center, the calculation of relevant key performance indicators for each plant, according to international standards, is performed. In detail:


  • Data are collected in a Cloud Database Center (or dedicated database centers according to the client’s need). From here, stakeholders can use the data accordingly for future analysis and performance tracking. Each PV plant can be monitored on a cloud server via a web browser or mobile device.
  • The Control Center software consists of a database, a synchronizer, a business logic unit, a notification server and a front-end unit.
  • The database stores all data necessary for the operation of the solution in a centralized manner for all monitored sites.
  • The synchronizer manages all IP connections with the field-deployed controllers, collects data from them either periodically or on an event-driven basis and relays any user action events from the front-end to the field-deployed controllers.
  • Business logic performs data processing to produce statistics, performance ratios, reports and alarms.
  • A notification server notifies selected users via email/SMS in case of critical alarms.
  • The front-end unit undertakes the structured presentation of the data to a multitude of users by implementing web technologies and integrating video feeds from the CCTV system for specific DVRs.

Power Plant Controller (PPC)

Power Plant Controller (PPC) is an intelligent vendor-independent system for dynamic PV power plant control and grid code compliance, customizable to satisfy any grid requirement while ensuring interoperability with plant SCADA systems. Unity PPC controls the output of the PV plant at the Point of Common Coupling, using the plant inverters, meters, statcom, capacitors, breakers and peripheral controllers – providing near real-time capabilities for plant disconnection or generation stop, active and reactive power control, as well as power ramp rate control.

It offers control and monitoring capabilities to the grid and plant operator, intelligent closed-loop control of active and reactive power, circuit breaker control, as well as monitoring of electrical, meteorological quantities, breakers and power control modes and states.


         Interoperable for a wide variety of inverters and meters.

         Customizable for new grid code requirements is implemented upon request.

         Compatible with grid operator systems , using a number of standard IP or RS-485

         protocols (IEC 60870-5-104, DNP3, Modbus) as well as digital or analogue interfaces.




Unity Power Plant Controller allows you to regulate a lot of parameters:

  • Active / reactive power control with ramp rate control
  • Feedback from generation and compensation equipment, meteo instruments, circuit breakers
  • Circuit breaker control, plant disconnection and ramp rates in power up
  • Data, digital and analogue interfaces, fully extensible and customizable
  • Supporting most inverters, meters and protection devices
  • Integration of new devices, grid code or plant operator requirements upon request
  • Interoperable with Unity monitoring system

Control functions

  • Active Power Control P
  • Ramp Rate Control 
  • Reactive Power Control Q, Q(P), Qnight 
  • Power Factor Control cosφ, cosφ(P) 
  • Voltage Regulation AVR, Q(V), cosφ(V) 
  • Frequency Support P(f) 
  • Circuit Breakers control 
  • Stop Plant Generation