A fair DC tariff is one a driver can predict before the session starts: a published price, built from the operator’s own cost lines, on a basis that matches how DC charging delivers energy. For a compact 22 kW DC unit like the EV-RHDC30K-L, per-kWh pricing is usually the easiest basis to defend, because DC sessions are short and the car’s own charging curve — not the charger — decides how the minutes are spent. There is no market rate to copy; fairness is a structure, not a number.
Key Takeaways
- Fair means published in advance, built from your own cost lines, and explainable in one sentence — not a copied market rate.
- At DC speeds, per-minute pricing penalises cars that taper or accept less power; per-kWh prices the energy itself.
- A compact 22 kW unit sells dwell-time top-ups, a different product from corridor fast charging — price it on your site’s pattern.
- The tariff lives in the operator’s platform over OCPP; the charger reports the sessions it is priced on.
Start From Your Own Cost Lines
A tariff that reflects costs can be explained; one copied from another network cannot. The cost lines an operator carries:
- Electricity — your supply tariff per kWh, plus any demand or capacity element your contract charges for peak draw.
- Platform and payment costs — the back-office fee for running sessions over OCPP, plus payment processing.
- Site costs — the bay, the connection and the installation, spread over the unit’s life.
- Maintenance — inspections, connector wear and repairs.
Our pricing models guide covers the generic structures. The DC-specific work is choosing the basis that behaves fairly at DC speeds, which is where tariffs most often go wrong.
How Each Basis Behaves at DC Speeds
| Tariff basis | What the driver pays for | Behaviour on a 22 kW DC unit |
|---|---|---|
| Per kWh | Energy delivered | Tracks what the driver came for. Taper changes how long the session takes, not the price per unit received |
| Per minute | Time connected | Minutes are large units at DC speeds: a car in taper, or one with low DC acceptance, pays the full minute rate for shrinking energy — the fairness trap |
| Per session | One plug-in | A five-minute splash pays the same as a long session, so it suits fleets and yards better than public use |
| Session fee plus per kWh | Connection, then energy | The fee covers fixed per-session costs; the energy part stays proportional. Two numbers to publish, both explainable |
The pattern behind the table: on DC, a session lasts minutes and the car’s charging curve fills them unevenly — full rate early, tapering late. A per-minute price quietly charges the tapering driver more per kWh for the same charger; per-kWh pricing avoids building that penalty in. Our explainer on why DC fast charging costs more to provide covers the cost side a DC tariff must recover.
One Worked Example — Every Figure Invented
All figures here are invented for illustration. Suppose an operator sets €0.55 per kWh. A driver taking a 20 kWh top-up pays €11.00, whether the car delivered it in 55 minutes or tapered across 80. On a per-minute tariff invented at €0.25, the same two sessions cost €13.75 and €20.00 — the slower car pays nearly double per kWh for identical energy. That spread, not the level, is the fairness question. Whatever basis you choose, publish it where the driver sees it before the session starts — on the charger or in the platform app — and keep one basis long enough for drivers to learn it.
The Unit Behind This Tariff
The EV-RHDC30K-L is a floor-standing compact DC charger: 22 kW per its product page, single connector, LCD display, IP54, and OCPP 1.6J, so sessions report to the operator’s platform where the tariff is set and applied. Operators planning the business case behind the tariff can build on our commercial charging range.
Frequently Asked Questions
What is a fair price per kWh for DC charging?
There is no published fair rate. A defensible price covers your own electricity (including any demand element), platform and payment costs, site costs and maintenance, with your margin on top — computed from your invoices, not from another network’s price board.
Why does per-minute pricing cause complaints on DC chargers?
Because a DC session’s energy rate falls as the battery fills. Two drivers can take the same energy in very different times depending on their car’s charging curve, and per-minute pricing charges the slower one more per kWh. Per-kWh pricing prices the energy, not the car’s curve.
Should a compact DC unit price like a motorway fast charger?
No. A 22 kW unit sells a different product — a top-up during a stop of half an hour or more, not a corridor refill in minutes. Price it against your own costs and your site’s dwell.
Related Reading
- How Much Do EV Charging Stations Charge? Pricing Models Explained
- Why Is DC Fast Charging Expensive?
- Is an EV Charging Station Business Profitable?
