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An EV does not need petrol, which is not the same as being free. Every kilowatt-hour that goes into the battery arrives on your TNB bill — and it arrives in a way that the usual advice, “multiply the kWh by your electricity rate”, gets wrong.
Under the tariff in force since July 2025, adding consumption does two things at once: it costs the marginal rate, and it reduces an efficiency incentive your household was already receiving. Both land on the same bill.
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The domestic tariff is not one price per unit. It is built from separate components — energy, capacity, network and retail — with a fuel adjustment that is reset monthly, an Energy Efficiency Incentive that steps down as consumption rises, and thresholds at which other charges begin to apply.
The marginal cost of one more unit, at or below 1,500 kWh a month, is 44.43 sen — the energy, capacity and network charges added together. Above that threshold the same calculation gives 54.43 sen. Neither figure is what your bill divided by your units would show, and neither is what an extra 150 kWh will actually cost you.
This part is simple, and it is the part people get right:
A car using 15 kWh per 100km, driven 1,000km a month, needs about 150 kWh. Real-world consumption on Malaysian roads — traffic, air conditioning, the way you drive — usually runs above the manufacturer's figure, so treat the brochure number as a floor.
Add a little more for charging loss: not every unit drawn from the wall reaches the battery, and the difference shows up on your meter rather than in the car.
Take the same 150 kWh of charging and add it to households of different sizes. The middle column is what the usual formula predicts. The one beside it is the actual difference between the two bills.
| Household before | “kWh × rate” | Actual increase | Effective per kWh |
|---|---|---|---|
| 400 kWh | RM66.64 | RM77.98 | RM0.52 |
| 700 kWh | RM66.64 | RM90.42 | RM0.60 |
| 1,000 kWhloses an incentive band | RM66.64 | RM78.12 | RM0.52 |
| 1,400 kWhcrosses 1,500 | RM66.64 | RM238.18 | RM1.59 |
The simple formula is wrong in the same direction every time, and it is wrong by more than a rounding error. The reason is the efficiency incentive: your household was receiving one, and pushing consumption up reduces it. You pay for the new units and you lose part of a rebate on the old ones.
This is the one worth knowing before you buy. Once monthly consumption exceeds 1,500 kWh, the higher energy charge applies to your entire consumption, not only the excess. TNB's own schedule labels that row “for all kWh”.
What that looks like in practice
A household at 1,400 kWh that adds 150 kWh of charging crosses the threshold. The bill rises by RM238.18 — an effective RM1.59 per kWh, against the 44.43 sen the simple formula assumes. The charging did not become expensive; the whole bill was repriced.
If your household already runs anywhere near that threshold, this is a real consideration in whether to charge at home at all, how much to charge at home versus elsewhere, and whether a time-of-use plan or solar changes the arithmetic. Check a few recent bills for your typical monthly consumption before assuming it does not apply to you.
People see a 50 kWh or 70 kWh battery and try to work out the cost of “filling it every day”. That is not how it works. Capacity determines how much energy the car can hold at once — how far it goes between charges — not how much energy you consume in a month.
Someone driving 500km a month in a 70 kWh car uses far less energy than someone driving 2,000km in a 50 kWh car. Distance and efficiency set the bill. Capacity sets the convenience.
Home charging goes onto your TNB bill at the domestic tariff. Public charging is billed by the operator at its own rate, and DC fast charging in particular is priced well above anything domestic.
That gap is why the ability to charge where you live matters so much to whether an EV works financially. A driver relying mainly on public fast charging gives up most of the running-cost advantage — which is the specific case the EV vs petrol calculator asks you to model with a home-versus-public split.
It depends far more on how much you drive than on the car. The energy needed is your monthly distance multiplied by the car’s consumption in kWh per 100km. What that energy costs, though, is not a single rate: the domestic tariff has several components and an efficiency incentive that tapers as your household consumption rises, so adding EV charging costs more per kWh than your current average suggests.
Because the extra consumption does two things at once. It costs the marginal rate for those units, and it reduces the Energy Efficiency Incentive your household was receiving — an incentive that steps down as total monthly consumption rises. Both effects land on the same bill. Across ordinary household sizes the simple multiplication understates the real increase by roughly 15% to 26%.
The higher energy charge applies to your entire consumption, not just to the units above the threshold. TNB’s own schedule labels it “for all kWh”. That makes the threshold a cliff rather than a step: a household just under it that adds EV charging can see a very large jump for a modest amount of extra energy.
No. Battery capacity determines how much energy the car can store at once, not how much you consume in a month. A 70 kWh car driven 500km uses far less energy than a 50 kWh car driven 2,000km. Your monthly cost tracks distance and efficiency, not capacity.
Almost always, and usually by a wide margin — public DC fast charging in particular is priced well above a domestic tariff. That gap is the main reason the ability to charge at home matters so much to whether an EV works out financially at all.
It can help if most of your charging happens overnight, because the off-peak rate is lower. It is an opt-in for domestic customers and it changes how all your household consumption is priced, not just the car, so it is worth checking against your actual usage pattern rather than assuming.
General educational guidance. Figures exclude the fuel adjustment, which is reset monthly, and assume a standard domestic supply rather than a time-of-use plan. Your own bill is the authority on what you pay — check it before making a decision that depends on these numbers.