The energy industry is full of technical jargon that can often be difficult to grasp. Use our glossary below to better understand key industry terms.

Further questions? Please contact us to speak with one of our experts.


Using your energy storage machine to charge when electricity prices are cheap and then discharge stored energy during peak periods when energy is more expensive.

Behind the meter (BTM)

Refers to generation or energy storage which is connected electrically on the load side of the meter, usually on the property or business owners’ site rather than at utility/grid level.

Capacity market

The capacity market is designed to ensure that there is always enough energy capacity on the grid to meet demand. The grid will buy capacity ahead of time in line with its forecasted demand. Energy storage owners can bid into this auction to provide capacity for an agreed price.

Centralised generation

Large-scale electricity generation (usually fossil fuel) which is distributed to multiple end users via a transmission and distribution network. Examples include coal-fired or nuclear power plants.


redT machines are self-contained units which are housed in standard shipping containers.

Demand charges

Additional charge levied on energy consumer for importing electricity during specific periods (usually during times of particularly high demand).

Demand management (Demand Side Response)

A grid support scheme whereby energy users are incentivised to either lower or shift their demand use at peak times. This can be achieved by using an energy storage machine to either reduce the amount you are importing from the grid without any interruption to your site operation.

Diesel Genset

A diesel-fuelled electricity generator.

Distribution Network Operator (DNO)

Distribution Network Operators own and operate the distribution network of towers and cables which bring electricity from the Transmission Network (operated by the System Operator) to homes and businesses. In the UK, this role is performed by different companies on a regional basis.


The liquid that flows around the redT energy storage machine. Located in large tanks and pumped around the system, the electrolyte stores energy and never degrades. It contains vanadium ions and is 70% water.

Frequency Response

A type of grid service which aims to regulate the electrical frequency on the network to within a given tolerance. Participants are paid to make their energy storage asset available for the service with an additional payment made for when their asset is utilised. The energy storage machine will be required to discharge or charge in response to an electrical signal to do so.

Grid services (Grid Balancing)

Get paid to provide “balancing” services to the grid. Discharge your storage when demand outstrips supply or charge your storage when supply outstrips demand.

In-front of the meter

Refers to generation or energy storage which is situated at utility/grid level or as part of the transmission network.

Internal Rate of Return (IRR)

A widely used performance measure which is used to evaluate the attractiveness of a project or investment.

Ion Exchange Membrane

This material forms a specially designed barrier, which allows certain particles to pass through it, but not others. This allows the redT machine to separate different types of vanadium from each other.

Kilowatt (kW)

Measurement of electrical power.

Kilowatt hour (kWh)

Measurement of electrical energy.

Mini grid

Common in off-grid locations, mini grids (also known as micro grids or isolated grids) consist of generation plus storage and a distribution network that provides energy to a localised group of customers.


A standardised design which can be scaled up or down as required.


A site with no connection to a national or regional electricity grid. Off-grid sites are often in remote areas and usually use diesel generators, or other forms of decentralised generation, to produce power.


A site with secure access to a national or regional electricity grid.

Inverter (Power Control System, PCS)

An inverter converts direct current (DC) to alternating current (AC).

Peak demand

Refers to times of the day when electricity consumption is highest and electricity prices are most expensive as a result.

Redox reaction

A perfectly reversible reaction which moves electrons between molecules. It gets its name from REDuction and OXidation. When a molecule is reduced, an electron is added. When a molecule is oxidised, an electron is removed. In a redox reaction, one molecule is reduced, whilst another is oxidised. The resulting movement of electrons causes an electrical current.

Renewable firming (time shifting)

The process of storing excess renewable generation for use at another time. Time shifting creates “firm” renewable energy which can be used 24 hours a day.

Service stacking

Perform multiple services with one system, layered (or stacked) on top of each other. For example, Time shifting solar energy, providing frequency response services and acting as a backup power source.

Spinning reserve

A specific “grid service” which can be provided by an energy storage machine to the grid. The grid will pay you to use your energy storage machine as back-up, providing rapid response energy to the grid when it is required.


Substations convert high voltage electricity from the transmission network into low voltage electricity for use in homes and businesses.

System Operator (SO)

System Operators manage the transmission network, which extends across a given country or region. The aim of the SO is to ensure the stable and secure operation of the entire transmission network. In the UK, this role is performed by National Grid.

Transmission network

The network of high-voltage electricity lines which transports electricity across a given region, usually from centralised generation to the network of substations.


Metallic element which can exist in four different oxidation states. Traditionally used in steel production, it is the 18th most abundant element on earth and more common than Nickel (22nd), Zinc (23rd) or Copper (24th).


Vanadium Redox Flow Machine.


A site which is connected to a national or regional grid, however this connection is unreliable or unstable meaning power cuts are common and security of supply cannot be relied on.