Glossary — depot electrification jargon in plain English

Glossary

Every acronym, in plain English

65 depot charging, grid and energy terms — defined simply, with no assumed knowledge. Search or jump to a letter.

A

AC charging: Slower, cheaper charging (typically up to 22 kW) suited to vehicles that sit for hours — ideal for overnight depot charging.
ADMD (After Diversity Maximum Demand): A realistic estimate of peak power that assumes not everything runs flat-out at the same time. It stops you from over-sizing (and overpaying for) your connection.
Amps (amperes): A measure of electrical current — how much electricity is flowing through a cable at once. Cables and fuses are rated in amps, which limits how much power they can safely carry.
ANM (Active Network Management): A DNO arrangement that gives you a connection faster or cheaper, on the condition that your power can be automatically limited at rare busy moments on the network.

B

Behind the meter: Equipment on your side of the electricity meter — your solar, battery and chargers — where the power you generate or store offsets what you'd otherwise buy.
BESS (Battery Energy Storage System): A large on-site battery that stores electricity — for example charging up cheaply overnight or from solar, then releasing it to help charge vehicles or shave peak demand.
BEV (Battery Electric Vehicle): A vehicle powered purely by a rechargeable battery and electric motor — no engine, no fuel tank. These are the vehicles a depot charging setup is built to serve.

C

Capacity charge (available capacity): A fee based on the maximum power you've reserved with the network, not how much you actually use. Reserve too much and you pay for headroom you never touch.
Capex vs Opex: Capex (capital expenditure) is the big upfront spend — chargers, cabling, grid works. Opex (operating expenditure) is the ongoing running cost — electricity, maintenance, software.
CCS (Combined Charging System): The standard rapid-charging plug for electric cars, vans, trucks and buses in the UK and Europe. If you buy DC chargers, CCS is almost certainly what you need.
Charge point management system (CPMS): The back-office software that monitors and controls your chargers — showing what's charging, spotting faults, applying smart-charging rules and pulling usage reports.
Chargepoint (charger): The unit your vehicle plugs into to charge. Depot chargers range from slow overnight units to powerful rapid chargers, and are chosen to match how your vehicles are used.
Civil works: The physical construction part of a charging project — digging trenches, laying cables and ducts, pouring foundations and installing groundworks for chargers.
Connector types (plugs): The physical plugs that link charger to vehicle. In the UK, Type 2 is standard for AC, CCS for DC rapid charging, and MCS is emerging for the biggest trucks.
Cost per mile: What it costs in energy to drive one mile — the fairest way to compare electric against diesel because it ignores everything except fuel efficiency and price.

D

DC charging (rapid charging): Faster, more powerful charging (50 kW to several hundred kW) for vehicles that need topping up quickly. More expensive per charger and harder on your grid connection.
Depot charging: Charging a fleet of vehicles at your own base — the yard, garage or depot they return to — rather than at public chargers. It's cheaper, more controllable and the focus of this whole guide.
Depot Charging Scheme: A UK government grant that helps fleet operators pay for depot chargepoints and the civil works to install them, through timed application windows.
DNO (Distribution Network Operator): The company that owns and operates the electricity distribution network in your region. You engage your DNO to increase or confirm the grid capacity available at your depot.
DUoS (Distribution Use of System charges): Charges built into your electricity bill for using the local network. They're higher at busy times of day and lower overnight — which rewards charging off-peak.
Duty cycle: The pattern of how a vehicle is actually used — distance driven, when it returns, and how long it rests. It's the starting point for designing any charging setup.
Dwell time (charging window): How long a vehicle sits parked and available to charge. Long dwell times let you use slower, cheaper chargers; short ones force faster, pricier charging.

E

Energy Management System (EMS): The 'brain' that coordinates your chargers, battery, solar and grid connection — deciding moment to moment where power should come from and go to, to minimise cost.

F

Flexibility (Demand Side Response): Being paid to shift or reduce your electricity use at certain times to help balance the national grid — for example by pausing charging for a short window.

G

Grid capacity: The maximum amount of power your site is allowed to draw from the network at any one moment, measured in kVA. Charging lots of vehicles at once can quickly use it up.
Grid connection: The physical link and contract that brings electricity from the public network into your site, with an agreed maximum amount of power you're allowed to draw.
Grid reinforcement (upgrade): Work by your DNO to increase the power available to your site — for example a bigger cable, a new transformer, or a new substation. It's often the biggest cost and the longest wait in a depot project.

H

Half-hourly (HH) metering: A meter that records exactly how much electricity you use in every 30-minute slot. Larger sites are on half-hourly metering, which unlocks cheaper time-based tariffs.

I

ICP (Independent Connection Provider): An accredited contractor that can carry out grid connection works — like laying cables and installing substations — as an alternative to the DNO doing it themselves.
IDNO (Independent DNO): A privately-owned network operator that can own and run the electricity network on a site instead of the regional DNO — sometimes offering a faster or cheaper connection.
ISO 15118 (Plug & Charge): A standard that lets a vehicle and charger recognise each other automatically when plugged in — no app or card needed to start charging and bill correctly.

K

kVA vs kW: kW (kilowatts) is the useful power delivered to a vehicle; kVA (kilovolt-amperes) is the apparent power your grid connection is rated in, accounting for power factor. DNOs frame capacity in kVA.
kW (kilowatt): A measure of power — how fast electricity flows right now. A charger's kW rating tells you how quickly it can fill a vehicle: the higher the number, the faster the charge.
kWh (kilowatt-hour): A measure of energy — the total amount of electricity used or stored. It's what you're billed for, and what a vehicle battery holds. One kWh is one kilowatt flowing for one hour.
kWp (kilowatt-peak): The rated maximum output of a solar installation in perfect sunshine. It's how solar systems are sized — a bigger kWp means more panels and more potential generation.

L

Load management (dynamic load management): A system that shares your available power across chargers so the total never exceeds your grid limit — throttling or pausing some chargers as needed.

M

Main fuse (service head / cut-out): The safety fuse where the electricity supply enters your building, rated in amps. It caps the total power your site can draw before anything else is even considered.
Maximum demand (peak demand): The highest amount of power your site draws at any single moment. It matters because your grid capacity and some charges are based on your peak, not your average.
MCS (Megawatt Charging System): An emerging super-high-power charging standard designed for the largest electric trucks, delivering far more power than CCS for very fast top-ups.
Microgrid: A joined-up local energy system — combining solar, battery, chargers and grid connection — that can balance itself and sometimes keep running if the main grid fails.
MPAN: The unique reference number for your electricity supply point — like a postcode for your meter. You'll be asked for it when arranging tariffs, connections or funding.

O

OCPP (Open Charge Point Protocol): A common 'language' that lets chargers from different manufacturers work with different management software — so you're not locked into one supplier forever.
Off-peak / on-peak: Off-peak is the cheap, quiet period (typically overnight) when electricity costs least; on-peak (or just 'peak') is the expensive, busy period, usually late afternoon and early evening.
OZEV: The UK government office responsible for supporting the switch to electric vehicles, including funding schemes for fleets and charging infrastructure.

P

p/kWh (pence per kilowatt-hour): The price of electricity per unit of energy — the number that decides your fuel cost. Compare it against diesel's cost-per-mile to see your saving.
Payback period: How long it takes for your savings to repay the upfront cost of going electric. After the payback point, the savings are money in your pocket.
Peak shaving: Trimming the highest spikes in your power use — usually with a battery or smart charging — so you never breach your grid capacity or trigger peak-time charges.

R

Range: How far an electric vehicle can travel on a full charge. You match range to your routes, with a sensible buffer for cold weather, load and detours.
Range anxiety: The worry that a vehicle will run out of charge before finishing its route or reaching a charger. Good planning and reliable depot charging largely design it away.
Resilience (backup power): How well your depot keeps running if the grid supply drops — for example whether a battery or backup generator can keep critical vehicles charging.

S

Self-consumption: Using the electricity your solar panels generate directly on site, rather than exporting it to the grid. The more you self-consume, the more value your solar delivers.
Simultaneity (diversity) factor: An assumption about how many chargers are drawing full power at the same time. A lower factor means a smaller, cheaper grid connection is needed.
Smart charging: Software that automatically controls when and how fast each vehicle charges — to hit cheap tariff windows, stay within your grid limit, and make sure every vehicle is ready on time.
Solar PV (photovoltaics): Panels — usually on your roof or a canopy — that turn daylight into electricity you can use on site, cutting the amount you buy from the grid.
Standing charge: A fixed daily fee on your electricity bill just for being connected — you pay it whether or not you use any power.
State of charge (SoC): How full a battery is right now, shown as a percentage — like a fuel gauge for an electric vehicle or a storage battery.
Substation: Equipment that steps the high-voltage electricity in the street down to a voltage your site can use. A big depot may need its own dedicated substation.

T

TCO (Total Cost of Ownership): The full lifetime cost of running a vehicle or fleet — purchase, energy or fuel, maintenance, and so on — not just the sticker price. Electric fleets often win on TCO even when they cost more upfront.
Three-phase power: A type of electricity supply that delivers three times the punch of a standard household (single-phase) supply. Almost every depot doing meaningful charging needs three-phase power.
Time-of-use (TOU) tariff: An electricity tariff where the price per unit changes through the day — cheap when demand is low (often overnight), expensive at peak times.
Transformer: The core piece of kit inside a substation that converts electricity to the right voltage for your site. Its size sets a ceiling on how much power you can draw.

U

Uptime: The percentage of time your chargers are working and available. Low uptime means vehicles can't charge and your operation grinds — so reliability is as important as raw speed.

V

V2G (Vehicle-to-Grid): Technology that lets a parked electric vehicle send power back out of its battery — to the building, or to the grid — instead of only drawing power in.
Vendor lock-in: Getting stuck with one supplier because your chargers or software won't work with anyone else's — leaving you unable to switch without expensive replacement.
Volts (voltage): A measure of the electrical 'pressure' pushing electricity along a wire. UK sites are typically either single-phase (230V) or three-phase (400V).