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Studer MPPT Solar Charge Controllers VS-70 VarioString series

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Studer MPPT Solar Charge Controllers VS-70 VarioString series

With the MPPT solar charge controllers of the VarioString series, the solar installations will see their costs optimised while at the same time guaranteeing a better than average solar production and keeping the battery in the best condition possible.

Despite the conversion from a high voltage solar (600-900V) to 48V battery voltage, and galvanic isolation between the PV and battery, the VarioString achieves an efficiency >98%: the highest efficiency in the world in its category.

The VarioString is designed to be used in all types of solar systems, and the combination of the VarioString + Xtender results in a highly efficient system. The communication between the devices permits the synchronisation of the battery charge cycle regardless of the technology (lead acid, lithium, nickel, etc…). Unlike other all-in-one hybrid solutions, the VarioTrack + Xtender allows to independently select the appropriate capacity of solar PV and inverter/charger, resulting in a more finely tuned system design.

Recommended PV power [W] Battery voltage Unom [V] PV voltage U [V] Max charge current Imax [A]
VS-120 7000 48 250-500 parallel / 500-750 series 120
VS-70 4200 48 250-500 70

Features and performances

  • Reduces Balance of System costs (eliminates expensive wiring for parallel strings, saving wires, connectors, junction boxes, fuses, space, time, etc.)
  •  Safe, simple and trouble free connection with SUNCLIX™ (Phoenix Contact “tool free”) PV connector
  •  Safety, guaranteed, thanks to the reinforced isolation between the PV generator and battery and between the two PV inputs of the VS-120. This allows for independent earthing of the battery and/or solar modules*.
  •  World champion for efficiency in isolated converter with >98 % conversion efficiency
  •  7kW per unit and up to 15 units in parallel: 105kW
  •  4 step charger fully programmable for longer battery life
  •  9 LEDs to monitor status and current
  • Full display, configuration and data acquisition with RCC-02/03 and/or via the internet with the Xcom LAN/Xcom-GSM or via SMS with Xcom-SMS


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The VS-70 is recommended for PV capacities up to 4.2kWp, and charges the battery with a maximum current of 70A. The solar modules are connected in series to form one single string (up to 600V) connected to the VS-70, all this without special tools and with reusable connectors.

The battery management parameters can be adjusted on the inside of the device. On the outside, an LED display indicates the battery charge current and state of the VS-70.

Given the specific system needs, several accessories can be added such as the Remote Control and Programming Centre RCC-02/03, a module with 2 auxiliary contacts ARM-02, a battery temperature sensor BTS-01, a battery status processor BSP-500/1200, or one of the communication sets Xcom-LAN/GSM/SMS.

The VS-70 has a remote entry which provides the option to control the system from several parameters that can be programmed with the RCC-02/03.

The combination of the VS-70 and Xtender series is the ideal solution for hybrid systems with several power sources such as solar PV, genset, etc.…