Electric energy storage device of the flywheel type: energy is stored as kinetic energy E = ½ M.V².

With the use of concrete as the storage material, and a very long life, cost of storage with VOSS is much lower than with batteries. Nominal storage time of one hour is optimal for smoothing the production of photovoltaic plants.

For safety reasons, the 10 kWh VOSS should be surrounded by one meter of absorbent material This will dissipate the kinetic energy in case of problem and avoid a chain reaction.

It is not allowed to surround the flywheel by a thick and rigid material (steel, concrete etc.) : upward projection hazard.

Installation can be below the ground or above the ground.

Examples of absorbent material:

– Sand (Big Bag)

– Gravel (Big Bag or gabion)

– Water (Rigid or soft tanks)

– Topsoil etc..

Les Spécifications

Énergie nominale 10 kWh
Nominal capacity 10 kW
Nominal voltage

– with inverter option Nominal power

450 à 700 V CC

En triphasé 50/60Hz:

  • 380 à 415 V
  • 380 à 500 V
  • 525 à 690 V
Mass 5.000 kg
Maintenance Annuel
Life 30 ans

30 000 cycles

Temperature -15°C à + 55°C

Transport and handling

From the top: crane.


Communication: the motor drive is using the Ethernet/IP protocol as standard. Other protocols are available (optional).

Digital: the direction and the power of charge/discharge are transmitted to the drive by a central computer.


Annual visit for: filter cleaning, level of lubricating oil etc.

No wearing parts to change periodically on the mechanical side. Small parts to change every 5 to 10 years on the electrical side (fans, capacitors, batteries etc.).

Electrical connection

Power: it can be connected to the grid according to 3 types of architectures:

-1) The standard connection is directly on the DC bus of the motor drive. This allows connecting several flywheels in parallel like batteries. The DC bus is connected to the AC grid by a central inverter (not supplied).

-2) Each flywheel is connected directly to the grid via its own inverter (AFE).

-3) The solar panels and the drive’s DC bus are connected to the grid via the solar inverter. With this type of architecture, there is only a single inverter instead of two. It also reduces energy conversions losses.

(In development.)