Running cost comes down to wattage, hours and your rate. In Montana the rate is 14.67 cents per kWh, which is 20.4 percent below the national average. Here is what that means for a electric tankless water heater.
A electric tankless water heater drawing 18,000 W costs $2.64 per hour in Montana. Run 0.5 hours a day that is $1.32 daily, $39.61 a month and $482 a year, which is $124 less than the same appliance at the US average rate.
Electric tankless water heater cost at Montana rates
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Planning estimate. The rate box is prefilled with a regional average; the figure on your own bill is the one that matters. Power is draw while running, not while switched on.
Cost by hours used per day in Montana
| Hours/day | Energy | Per day | Per month |
|---|---|---|---|
| 1 h | 18.00 kWh | $2.64 | $79.22 |
| 2 h | 36.00 kWh | $5.28 | $158 |
| 4 h | 72.00 kWh | $10.56 | $317 |
| 6 h | 108.00 kWh | $15.84 | $475 |
| 8 h | 144.00 kWh | $21.12 | $634 |
| 12 h | 216.00 kWh | $31.69 | $951 |
| 24 h | 432.00 kWh | $63.37 | $1,901 |
Cost by wattage at 14.67 cents
| Rated power | Per hour | Per day | Per month |
|---|---|---|---|
| 10,000 W | $1.47 | $0.73 | $22.01 |
| 14,000 W | $2.05 | $1.03 | $30.81 |
| 18,000 W | $2.64 | $1.32 | $39.61 |
| 24,000 W | $3.52 | $1.76 | $52.81 |
| 36,000 W | $5.28 | $2.64 | $79.22 |
Find the row matching the nameplate on your own unit. Within a single appliance category the spread is often wider than the difference between categories, so the label is worth reading.
Tankless sizing in Montana
Incoming groundwater temperature sets how hard a tankless unit works, and it is colder in winter everywhere. Montana sees a wide seasonal swing, so a unit sized comfortably for summer can struggle to hit target temperature at full flow in winter, when incoming water is considerably colder. The instantaneous draw dominates the figure above rather than standby loss, which is the main advantage tankless has over a tank.
Why Montana pays what it does
Montana is a regulated market, so your utility is the only supplier and the rate is set through the state commission rather than by competition. Pricing tends to be steadier than in deregulated states, and there is no switching decision available. The levers are all on your side of the meter.
At 14.67 cents, Montana ranks 13 of 51 from cheapest to most expensive. The West regional average is 19.65 cents. Roughly half of any residential bill is transmission and distribution rather than generation, which is why rates keep climbing even when fuel prices fall.
How this compares across the country
The same electric tankless water heater on the same schedule, in the cheapest and dearest states:
| State | Rate | Per month | Per year |
|---|---|---|---|
| Idaho | 12.35¢ | $33.35 | $406 |
| Utah | 12.96¢ | $34.99 | $426 |
| Montana | 14.67¢ | $39.61 | $482 |
| California | 33.25¢ | $89.78 | $1,092 |
| Hawaii | 52.00¢ | $140 | $1,708 |
Lowering the number in Montana
- Lower the setpoint if it is set above what you need. Every degree of unnecessary temperature rise costs energy on every draw.
- Avoid running multiple hot taps at once. Splitting flow across fixtures forces the unit to work harder to reach target temperature at each.
- Descale periodically in hard-water areas. Mineral buildup on the heat exchanger reduces efficiency and shortens unit life.
- Fix any recirculation pump running constantly. Continuous recirculation defeats much of the standby-loss advantage tankless offers.
Offsetting it with solar in Montana
This load uses about 9.00 kWh a day. Covering that would take roughly 7 standard 400 W panels at typical sun hours, an array of about 2.80 kW. Because it offsets electricity worth 14.67 cents rather than the national 18.44 cents, the same array is worth less here than the national payback figures suggest.
Electric tankless units draw more instantaneous power than most homes can supply, let alone a solar system. This is rarely a viable solar load. Full sizing, including battery and inverter requirements, is on the solar sizing page for this appliance.