Running cost comes down to wattage, hours and your rate. In Missouri the rate is 13.68 cents per kWh, which is 25.8 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 $2.46 per hour in Missouri. Run 0.5 hours a day that is $1.23 daily, $36.94 a month and $449 a year, which is $156 less than the same appliance at the US average rate.
Electric tankless water heater cost at Missouri 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 Missouri
| Hours/day | Energy | Per day | Per month |
|---|---|---|---|
| 1 h | 18.00 kWh | $2.46 | $73.87 |
| 2 h | 36.00 kWh | $4.92 | $148 |
| 4 h | 72.00 kWh | $9.85 | $295 |
| 6 h | 108.00 kWh | $14.77 | $443 |
| 8 h | 144.00 kWh | $19.70 | $591 |
| 12 h | 216.00 kWh | $29.55 | $886 |
| 24 h | 432.00 kWh | $59.10 | $1,773 |
Cost by wattage at 13.68 cents
| Rated power | Per hour | Per day | Per month |
|---|---|---|---|
| 10,000 W | $1.37 | $0.68 | $20.52 |
| 14,000 W | $1.92 | $0.96 | $28.73 |
| 18,000 W | $2.46 | $1.23 | $36.94 |
| 24,000 W | $3.28 | $1.64 | $49.25 |
| 36,000 W | $4.92 | $2.46 | $73.87 |
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 Missouri
Incoming groundwater temperature sets how hard a tankless unit works, and it is colder in winter everywhere. In Missouri the seasonal swing is smaller, which keeps a tankless unit closer to its rated output year-round. The instantaneous draw dominates the figure above rather than standby loss, which is the main advantage tankless has over a tank.
Why Missouri pays what it does
Missouri 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 13.68 cents, Missouri ranks 7 of 51 from cheapest to most expensive. The Midwest regional average is 16.55 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 |
| Missouri | 13.68¢ | $36.94 | $449 |
| California | 33.25¢ | $89.78 | $1,092 |
| Hawaii | 52.00¢ | $140 | $1,708 |
Lowering the number in Missouri
- 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 Missouri
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 13.68 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.