The most expensive place in America to run a Supercharger

Of the 96 filed utility rates the engine prices, the two most expensive places to dispense a kilowatt-hour are Oahu and Maui. No mainland territory is close, and the reason is not one line on the bill but two.

This post prices the same eight-stall site under Hawaiian Electric's Oahu and Maui books and under the engine's default PG&E rate, so the gap is in dollars rather than adjectives. Every figure is read from the July 2026 effective-rate summaries the utility files with the state commission.

Two lines, both large#

Hawaiian Electric's large-power schedule, Schedule P, is the class a Supercharger site lands in once its demand clears the island's floor. It has a simple shape: one energy rate for every kilowatt-hour, at every hour, in every season, plus one demand rate for every kilowatt of the month's peak.

For comparison, the energy charge on PG&E's BEV-2 rate blends to about $0.215 per kWh at the engine's default time-of-use mix, and its demand component is a $95.56 subscription per 50 kW block.

The energy figure is the one that circulates. Thirty-eight cents a kilowatt-hour on Maui, flat, with no off-peak window to shift into. That number is correct, and on its own it is the highest energy rate in the library. It is also only the smaller of the two lines once a site is actually running.

What the demand charge adds#

The engine subscribes 150 kW of capacity per stall, so an eight-stall site bills 1,200 kW of demand every month whether or not a single car arrives. On Maui that is 1,200 × $29.44 × 12, or $423,936 a year. Per stall, per month: $4,416, before the first kilowatt-hour is sold. On Oahu the same arithmetic gives $4,806 a stall.

Here is the default site, on the Standard ramp, in its first year. It dispenses 609,600 kWh and buys 692,727 after the 12% loss factor:

The electricity bill alone is two and a half times the site's revenue. The demand line, not the headline energy rate, is most of the reason: on Oahu it is $461,376 of a $695,301 bill. Thirty-eight cents was the smaller problem.

A reader could object that a ramping site is the wrong test, since the demand charge is spread over a thin first year. Hold the site at a flat 400 kWh per stall per day from month one, a busy mature site dispensing 1,104,000 kWh a year, and the effective cost per kWh falls to $0.816 on Maui and $0.802 on Oahu. Better, and still three times California's $0.269 at the same volume.

The retail price that clears it#

The engine solves for the retail price at which a scenario's fifteen-year economics first pass its internal viability test, a composite of payback, cash position and IRR, holding everything else constant. That number is the cleanest way to say what the islands require:

A mainland operator at a good site sets a price in the forties or fifties of cents and the number stays mostly out of the conversation. On the islands the equivalent figure is between ninety cents and a dollar thirty, which is a different product at the plug. That is the sentence Hawaii forces an operator to say out loud.

Why the islands are different#

Hawaii generates most of its electricity from imported oil. Schedule P's energy charge is dominated by an energy cost recovery clause indexed to fuel, which resets every month; it is the fastest-moving component in the entire tariff library, and the figures above are the July 2026 values. A revenue balancing adjustment of 17.8% on Maui sits on the non-fuel components on top of that. Island grids also carry capacity on a small base with no neighbours to lean on, which is why the demand rates land in the thirties of dollars per kilowatt when most mainland books sit in the teens or lower.

None of that is a criticism of the rate design. It is the cost of power on an island, filed and published. The point is that a Supercharger converts it into a per-kWh margin problem at a scale nothing on the mainland matches. Maui already has a twelve-stall Supercharger at the Puunene Shopping Center in Kahului, so the question is not whether the stalls get built. It is what the operator's bill looks like.

What the model does not include#

Hawaiian Electric files a separate pilot for large EV charging, Schedule EV-P: a $4.00 per kW demand charge instead of $32, and a three-window time-of-use energy rate designed to pull charging into the solar-rich middle of the day. For a site that qualifies it roughly halves the bill. The engine does not model it as the canonical row because it is capped at 500 accounts and sunsets on 17 March 2027; a site underwritten on a rate that may not exist when the stalls open is underwritten on the standard schedule. The utility rankings mark the Hawaii rows with that disclosure.

The monthly fuel reset cuts both ways too. A site modelled in July is modelled at July's clause value, and the engine's annual escalation assumption is a smooth 5% on top of that, which is a convention rather than a forecast for oil.

The utility rankings publish all 96 rows in order, the Supercharger economics map shows where the islands sit against the mainland at a glance, and demand charges, explained covers why the second line on the bill is the one that decides. To run a specific Hawaii address, the scenario wizard resolves the island book automatically.

Rates are Hawaiian Electric's effective-rate summaries dated 1 July 2026, read from the utility's filed PDFs; the energy cost recovery clause changes monthly. Engine outputs are model projections under the stated assumptions, not advice or guarantees.