Running cost comes down to wattage, hours and your rate. In Maryland the rate is 21.77 cents per kWh, which is 18.1 percent above the national average. Here is what that means for a central air conditioner.
A central air conditioner drawing 3,500 W costs $0.76 per hour in Maryland. Run 8 hours a day that is $6.10 daily, $183 a month and $2,225 a year, which is $340 more than the same appliance at the US average rate.
Central air conditioner cost at Maryland 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 Maryland
| Hours/day | Energy | Per day | Per month |
|---|---|---|---|
| 1 h | 3.50 kWh | $0.76 | $22.86 |
| 2 h | 7.00 kWh | $1.52 | $45.72 |
| 4 h | 14.00 kWh | $3.05 | $91.43 |
| 6 h | 21.00 kWh | $4.57 | $137 |
| 8 h | 28.00 kWh | $6.10 | $183 |
| 12 h | 42.00 kWh | $9.14 | $274 |
| 24 h | 84.00 kWh | $18.29 | $549 |
Cost by wattage at 21.77 cents
| Rated power | Per hour | Per day | Per month |
|---|---|---|---|
| 2,000 W | $0.44 | $3.48 | $104 |
| 2,500 W | $0.54 | $4.35 | $131 |
| 3,000 W | $0.65 | $5.22 | $157 |
| 3,500 W | $0.76 | $6.10 | $183 |
| 5,000 W | $1.09 | $8.71 | $261 |
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.
Cooling season in Maryland
Maryland sits in the middle band for cooling demand, typically three to four months of real use. The annual figure therefore lands well below the twelve-month projection, and shoulder-season months often need only intermittent operation.
Why Maryland pays what it does
Maryland 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 21.77 cents, Maryland ranks 37 of 51 from cheapest to most expensive. The Northeast regional average is 25.91 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 central air conditioner on the same schedule, in the cheapest and dearest states:
| State | Rate | Per month | Per year |
|---|---|---|---|
| Idaho | 12.35¢ | $104 | $1,262 |
| Utah | 12.96¢ | $109 | $1,325 |
| Maryland | 21.77¢ | $183 | $2,225 |
| California | 33.25¢ | $279 | $3,398 |
| Hawaii | 52.00¢ | $437 | $5,314 |
Lowering the number in Maryland
- Raise the thermostat before anything else. Each degree warmer cuts compressor runtime, and runtime is the entire cost. Going from 70 to 74 commonly reduces cooling energy by a fifth or more.
- Change the filter every one to three months. Restricted airflow lengthens every cycle and strains the blower.
- Seal and insulate ducts. Duct losses in an unconditioned attic routinely waste 20 to 30 percent of what the system produces.
- Run ceiling fans alongside it. A fan costs roughly a cent an hour and lets most people sit comfortably three degrees warmer.
- Shade the condenser, not the airflow. A unit in direct sun works harder, but blocking airflow around it makes things worse.
Offsetting it with solar in Maryland
This load uses about 28.00 kWh a day. Covering that would take roughly 20 standard 400 W panels at typical sun hours, an array of about 8.00 kW. Because it offsets electricity worth 21.77 cents rather than the national 18.44 cents, the same array is worth more here than the national payback figures suggest.
A central system is a large enough load that it usually determines the size of the whole array rather than being an add-on to it. Full sizing, including battery and inverter requirements, is on the solar sizing page for this appliance.