EV charging and demand charges
On many larger business tariffs, you pay for the energy you use and for your highest half hour of demand in a peak price window. So the same km can cost very different amounts, depending on when your vehicles charge.
How peak price windows work
| Network | Peak price window | How it applies |
|---|---|---|
| Ausgrid | 3pm to 9pm, working weekdays | Larger business tariffs charge for the highest half-hour demand in this window |
| Endeavour Energy | 4pm to 8pm, business days | Demand charges apply to peak periods only |
Vans that return at 5pm land in the middle of both windows. Check your own bill and contract, as retail contracts can measure demand differently, and one busy half hour can stay on your bill for months.
An example
Ten electric vans each drive 150 km a day, on an Ausgrid EA305 example site.
| Charging plan | Energy a year | Demand charge a year | Added to bill a year |
|---|---|---|---|
| Plug in at 5pm, no limit | $28,781 | $14,780 | $43,561 |
| Plug in at 5pm, limited to 40 kW | $23,881 | $0 | $23,881 |
| Wait until 9pm | $21,081 | $0 | $21,081 |
These are estimates using 25c/kWh in peak and 18c/kWh off peak. Your own figures will differ. Run your own numbers.
Three ways to keep it down
- Charge after the peak price window. Most chargers can be set to start later.
- Use load management. It limits the total charging power, so it can stay under your existing peak.
- Add a battery. It can supply the chargers during the peak price window, although it adds cost.
Watch your tariff
Extra load can change your tariff. A small site that passes 160 MWh a year may move to a large-customer tariff with demand charges, so check this before you sign anything.
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