Kilowatts to Megawatts

Adding Charger Kilowatts Up into a Site Connection

Every charge point on a depot or hub is specified in kilowatts — 7.4, 11, 22, 50, 150, 350. The distribution network operator, on the other hand, wants one number in megawatts on the connection application. Somewhere between the stall schedule and that form the arithmetic has to happen, and it is the same sum whether you are electrifying six vans behind a builder's merchant or forty tractor units at a logistics park.

Conversion factor: 1 kW = 0.001 MW, so divide the connected kilowatts by 1,000. Thirty AC points at 11 kW is 330 kW connected, which is 0.33 MW — the figure that goes on the application before any diversity allowance is argued.

Where the Kilowatts Accumulate

Slow AC posts on long dwell

A 7.4 kW single-phase or 11 kW three-phase post is small on its own, but car parks buy them in dozens, and dozens of small numbers is how a site quietly reaches half a megawatt.

DC bays on short dwell

50 kW rapids, 150 kW high-power units and 350 kW ultra-rapids move the total in big steps: four ultra-rapid stalls alone are 1.4 MW of installed capacity.

Depot yards that plug in together

Vehicles come home inside a window of an hour or two, so a yard behaves very differently from a public forecourt where arrivals are spread across the day.

Heavy-vehicle dispensers

A single megawatt-class outlet for trucks is worth more than an entire car park of AC posts, which is why truck stops are planned at medium voltage from the first sketch.

Turning a Stall Schedule into a Connection Figure

Work from the stall list you already have rather than a guess about the future, and keep each allowance as its own number so the assumptions stay visible when the design is questioned.

Enter the connected total in kilowatts

Multiply each charger class by its point count, add them up and type the sum in the left field. A mixed site of 20 × 22 kW plus 6 × 150 kW is 440 + 900 = 1340 kW, and the megawatt value appears as you type. A comma works as a decimal separator and spaces are ignored, so pasting 1 340 is fine.

Run the diversified figure as a second number

Convert the raw connected load first, then convert the diversified one. At a 0.6 factor that same 1340 kW becomes 804 kW, or 0.804 MW — quoting both tells the network operator what you installed and what you expect to import.

Reverse when the offer comes back in megawatts

Connection offers and transformer ratings arrive in MW or MVA. Press the swap button (↔) to run MW → kW and see how many charge points a 2 MW offer really supports — 2000 kW is thirteen 150 kW bays with a little left over for lighting and the shop.

Copy the plain number onto the form

The copy button hands over the bare figure with no unit and no spaces, which is what an application field or a load spreadsheet expects. Ctrl + C inside a field does the same thing.

Charger kW is output, not intake: a 150 kW DC unit delivering its rated output draws a few percent more from the supply because of conversion losses, and auxiliary loads — cabinet cooling, canopy lighting, payment terminals — sit on top of the charger total.

Charger Classes and What a Full Bank Draws

Per-point ratings you will meet in catalogues, each with a realistic stall count and the resulting site total in both units.

Charge point class	Per point	Points	Site total
AC single-phase, 32 A	7.4 kW	40	296 kW = 0.296 MW
AC three-phase, 16 A	11 kW	40	440 kW = 0.44 MW
AC three-phase, 32 A	22 kW	24	528 kW = 0.528 MW
DC rapid	50 kW	8	400 kW = 0.4 MW
DC high-power	150 kW	6	900 kW = 0.9 MW
DC ultra-rapid bank	350 kW	4	1400 kW = 1.4 MW
DC ultra-rapid hub	350 kW	10	3500 kW = 3.5 MW
Heavy-vehicle dispenser	1000 kW	4	4000 kW = 4 MW

Read down the last column and the pattern is plain: forty AC posts and one bank of four ultra-rapids differ by nearly five times in installed capacity while taking up similar amounts of tarmac. The charger mix, not the stall count, is what decides whether a site stays a low-voltage job or needs its own transformer on a medium-voltage feed.

What Helps While Sizing the Supply

Running totals as the stall list grows

Type each revised kilowatt subtotal straight over the last one and the megawatt figure follows immediately, so a phase-one and a phase-two layout can be compared in seconds.

Back to kilowatts when the offer is in MW

Swapping direction turns a quoted 1.5 or 3 MW capacity into kilowatts you can divide by charger rating to see how many bays it really carries.

Any power unit for the ancillary loads

The searchable dropdowns also hold watts, gigawatts, horsepower and BTU/h, so canopy lighting or a compressor rating can go through the same two fields.

Figures clean enough for the application form

Results carry up to eight decimals with spaced thousands, and the copy button strips everything except the digits.

Depot Electrification Questions

Does a 30-point depot really need a 0.33 MW connection?

Only if every post can run flat out at once. 30 × 11 kW is 330 kW of connected load, but a fleet that plugs in overnight has hours in which to share the energy, so such a yard is normally built with active load management and an import limit nearer 0.2 MW. The connected figure still matters for cable sizing, protection and the fault study — it is the import limit that gets negotiated down.

What diversity factor is realistic for overnight fleet charging?

Roughly 0.5 to 0.7 for a managed depot with twenty or more points, and 0.7 to 0.8 for a smaller site of four to ten. Uncontrolled charging is the awkward case: if every vehicle returns at 18:00 and plugs in, the factor approaches 1.0 for that half hour and the transformer ends up 30–40 % larger for a peak nobody benefits from.

At what site total does a charging hub need its own transformer?

Low-voltage connections thin out somewhere in the high hundreds of kilowatts, so once a site passes roughly 0.5 MW it is generally a dedicated substation on a medium-voltage feed. Remember that a transformer is rated in kVA or MVA rather than MW: at 0.95 power factor a 1 MW charging load asks for about 1.05 MVA before any headroom, and most designers then round up to the next standard frame size.

How much capacity does megawatt charging for trucks add to a site?

A great deal. MCS dispensers are specified from about 1000 kW upward, and a truck stop with a handful of them is planned around an aggregate installed capacity somewhere in the 5–20 MW band. In kilowatt terms one dispenser equals roughly 91 of the 11 kW posts you would fit in a car park, which is why these sites are treated as industrial connections rather than retail ones.

Can load management keep a growing depot inside its existing supply?

Frequently, and it is the cheapest capacity available. A dynamic controller measures the whole site's import and shares whatever headroom is left between the charge points, throttling them instead of tripping the main breaker. It buys stalls and time, not energy: if a fleet needs 4000 kWh before dawn and the connection allows 0.2 MW, a twenty-hour charging window is a hard limit no controller can move.