Depot electrification borrows vocabulary from fleet operations and from energy markets, and the two do not always agree. These are the terms used across this site, defined as the industry uses them.
Depot charging is the practice of charging a commercial vehicle fleet at the site it operates from, rather than at public chargers. It is the dominant model for vans, trucks and buses because vehicles return to a known location, sit still for a predictable period, and can be charged on the operator's own electricity supply.
Depot flexibility is the ability to move a depot's electricity demand in time without disrupting the operation it supports. Because vehicles usually sit far longer than they need to charge, the energy can be delivered in cheaper or less congested hours, which turns a fixed cost into a controllable one.
Where TOGL sits: This is the category TOGL builds in, which is why the site talks about flexibility rather than about charging software.
Also known as: Managed charging
Smart charging is the control of when and how fast vehicles charge, in response to price, site capacity or grid conditions, instead of charging every vehicle at full power the moment it plugs in. It requires no export of energy from the vehicle and no additional hardware beyond a controllable charger.
Unmanaged charging is the default behaviour where every vehicle draws full power as soon as it is plugged in. It concentrates the whole depot's demand into the period just after vehicles return, which is usually both the most expensive time to buy electricity and the moment the site peak is set.
Peak demand is the highest rate of electricity draw a site reaches, measured in kilowatts, rather than the total energy it consumes. It matters disproportionately because a site's grid connection, and much of what it pays in network charges, are sized against the peak and not against the total.
A demand charge is a component of an electricity bill based on a site's peak power draw rather than on the energy it used. In Great Britain it is usually charged as an availability rate on the site's agreed supply capacity in kVA, plus excess capacity charges where measured demand breaches it, rather than as a single monthly demand line. Lowering the peak is what makes it possible to contract for less capacity and to avoid excess charges, which is why load shifting can cut a bill without cutting a mile driven.
Also known as: Authorised supply capacity, ASC
Agreed supply capacity is the maximum power, in kVA, that a site has contracted with its distribution network operator. It is charged for whether or not it is used, and excess capacity charges apply when measured demand breaches it. Reducing it after flattening a peak is a commercial step agreed with the network operator, not an automatic bill change.
Also known as: DUoS
Distribution use of system charges are what a site pays its regional distribution network operator for using the local network. For half-hourly settled sites in Great Britain the unit rates vary by time band, and the early-evening Red band typically costs several times the overnight Green rate, which is a large part of why moving depot charging overnight saves money.
Load shifting is moving electricity consumption from one period to another without reducing the total consumed. In a depot it usually means spreading charging across the overnight window instead of concentrating it at the moment vehicles return.
Also known as: Connection capacity
A grid connection is the agreed maximum power, in kilowatts or megawatts, that a site may draw from the electricity network. Exceeding it is not permitted, so the connection sets a hard ceiling on how many vehicles a depot can charge at once and is often the binding constraint on electrifying a fleet.
Headroom is the capacity still available on a grid connection or on the network equipment serving it, after existing demand is accounted for. Actual headroom at the substation serving a site frequently differs from the nominal figure on the site's own connection agreement, which is why capacity questions are answered per site rather than per region.
Where TOGL sits: Grid connection intelligence, which answers this per depot, is in development at TOGL rather than live.
Grid upgrade deferral is avoiding or postponing the cost of increasing a site's connection capacity by managing demand to stay within the existing one. Upgrades are frequently the largest single cost in electrifying a depot and can take years to deliver, so deferral changes both the capital cost and the timetable of a fleet transition.
Departure readiness is the requirement that each vehicle holds enough charge to complete its duty by the time it is scheduled to leave. It is the constraint that separates fleet charging from other flexible loads: a saving that leaves a vehicle unable to start its shift has cost the operator more than it saved.
Where TOGL sits: TOGL treats readiness as a constraint on the optimiser rather than as one of its outputs, and depot operators keep the manual override.
Also known as: DSR
Demand-side response is the practice of paying electricity consumers to change their demand when the grid needs it, either by reducing consumption at times of system stress or by increasing it when there is surplus generation. It is how a controllable load such as a depot can earn revenue rather than only avoid cost.
A flexibility market is a mechanism through which network operators and system operators procure changes in electricity demand or generation, paying participants to deliver them. Access typically depends on the size of the asset, its ability to respond reliably within a defined window, and a route to market such as an aggregator.
Where TOGL sits: Flexibility market participation is planned at TOGL, not live. It depends on market access, asset eligibility and aggregator relationships.
An aggregator is an organisation that combines many small energy assets into a single portfolio large enough to participate in electricity markets. Individual depots are usually too small to qualify on their own, so an aggregator is the normal route for a fleet to reach flexibility revenue. In Great Britain an aggregator taking assets into the Balancing Mechanism is registered as a Virtual Lead Party under the Balancing and Settlement Code, a route open since 2019; there is no aggregator licence.
Also known as: BM
The Balancing Mechanism is the market the GB electricity system operator uses to balance supply and demand in each half-hour settlement period, accepting bids and offers from generators and from demand that can move. Independent aggregators have been able to take demand-side assets into it as Virtual Lead Parties since December 2019.
The Capacity Market pays assets to be available during periods of system stress, whether or not they are dispatched. Its cost is recovered from electricity demand in the winter early-evening peak, which is one of the reasons moving depot charging out of that window lowers a site's bill.
Also known as: V2G, bidirectional charging
Vehicle-to-grid is the export of energy from a vehicle battery back to the electricity network or to a site, rather than only drawing from it. It requires a vehicle that permits export, a charger certified for bidirectional flow, and a market that will pay for the energy, and those three conditions rarely align at fleet scale today.
Where TOGL sits: TOGL does not offer V2G. The platform is architected for bidirectional flow and TOGL will support it when it is commercially viable at fleet scale, so it is described as planned.
Also known as: TOU tariff
A time-of-use tariff prices electricity differently by time of day. For a depot this usually means a half-hourly settled contract where the energy price follows the wholesale market and the distribution charge steps between time bands, so the delivered cost of the same kilowatt hour can differ several-fold between the early evening and the small hours. It is what makes load shifting worth money.
Also known as: SoC
State of charge is how full a vehicle battery is, expressed as a percentage of its usable capacity. It is the input that determines how much energy a vehicle still needs and therefore how much freedom exists to move that charging in time.
Also known as: eHGV, electric truck
An electric heavy goods vehicle is a battery-electric truck, typically carrying between 300 and 600 kWh of battery against 50 to 100 kWh in a passenger car. That scale makes an eHGV both the largest single load a depot has to plan around and the most valuable flexibility asset on the site.
Where TOGL sits: eHGV support is in development at TOGL. Vehicle data access depends on manufacturers offering an API for those models.
Vehicle-first orchestration is an approach to charging control that starts from the state and schedule of each vehicle rather than from the charger it is plugged into. The distinction matters because the vehicle is the asset that moves between chargers and sites, holds the battery, and carries the duty that has to be met.
Also known as: CPMS
A charge point management system is the software that operates and monitors charging hardware, handling authorisation, sessions, faults and billing. It manages the chargers on a site, which is a different job from deciding which vehicles should charge when and at what rate.