Running cost comes down to wattage, hours and your rate. In Texas the rate is 16.44 cents per kWh, which is 10.8 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 $2.96 per hour in Texas. Run 0.5 hours a day that is $1.48 daily, $44.39 a month and $540 a year, which is $65.70 less than the same appliance at the US average rate.
Electric tankless water heater cost at Texas 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 Texas
| Hours/day | Energy | Per day | Per month |
|---|---|---|---|
| 1 h | 18.00 kWh | $2.96 | $88.78 |
| 2 h | 36.00 kWh | $5.92 | $178 |
| 4 h | 72.00 kWh | $11.84 | $355 |
| 6 h | 108.00 kWh | $17.76 | $533 |
| 8 h | 144.00 kWh | $23.67 | $710 |
| 12 h | 216.00 kWh | $35.51 | $1,065 |
| 24 h | 432.00 kWh | $71.02 | $2,131 |
Cost by wattage at 16.44 cents
| Rated power | Per hour | Per day | Per month |
|---|---|---|---|
| 10,000 W | $1.64 | $0.82 | $24.66 |
| 14,000 W | $2.30 | $1.15 | $34.52 |
| 18,000 W | $2.96 | $1.48 | $44.39 |
| 24,000 W | $3.95 | $1.97 | $59.18 |
| 36,000 W | $5.92 | $2.96 | $88.78 |
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 Texas
Incoming groundwater temperature sets how hard a tankless unit works, and it is colder in winter everywhere. In Texas 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 Texas pays what it does
Texas has a competitive retail electricity market, so the rate used here blends households on the utility default with households on shopped supply plans. If you have never switched supplier you are probably on the default, which is usually the more expensive side of that blend. Only the generation portion of your bill changes when you switch; delivery and outage response do not.
At 16.44 cents, Texas ranks 27 of 51 from cheapest to most expensive. The South Central regional average is 14.73 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 |
| Texas | 16.44¢ | $44.39 | $540 |
| California | 33.25¢ | $89.78 | $1,092 |
| Hawaii | 52.00¢ | $140 | $1,708 |
Lowering the number in Texas
- 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 Texas
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 16.44 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.