# Residential Demand Charges Explained: How One 15-Minute Spike Can Set Your Bill

> A few utilities now bill homes for their highest 15 minutes of power use, not only total kWh. Here is how a residential demand charge is calculated, why it matters for solar, and how to lower it, with 2026 examples.

- URL: https://solarexaminer.com/posts/residential-demand-charges-explained/
- Site: Solar Examiner (https://solarexaminer.com/)
- Category: Electric Rates
- Published: 2026-10-11
- Last verified: 2026-10-11
- Author: Tehseen Arbab

## Key takeaways

- A demand charge bills your highest rate of power use (kW) over a short window, usually 15 minutes, on top of or instead of part of the per-kWh charge.
- Colorado Springs Utilities' new solar option charges $0.3608 per kW per day in summer for the highest on-peak 15 minutes. A 5 kW peak costs $54.12 in a 30-day month.
- Solar reduces kWh but often does little for a weekday evening peak, when panels produce little.
- Staggering large appliances and using a battery during peak hours are the main ways to lower a demand charge.



Most home electric bills charge for energy: the total kilowatt-hours (kWh) you used in a month. A demand charge adds something different. It bills the highest rate at which you drew power, measured in kilowatts (kW), over a short window. One busy 15 minutes can set that charge for the whole billing period.

Demand charges have long been standard for businesses. A few utilities now use them for homes, often for customers with solar.

## kW vs kWh in One Minute

| Measure | What it is | Example |
|---|---|---|
| kW (demand) | How fast you use power at a moment | Oven (3 kW) + dryer (5 kW) running together = about 8 kW |
| kWh (energy) | How much you use over time | 8 kW for 15 minutes = 2 kWh |

**Formula:** kWh = kW × hours

A home can use modest total kWh and still set a high peak if several large appliances run at once.

## How a Demand Charge Is Calculated

**Demand charge = highest kW in the measurement window × rate per kW (× days, if the rate is daily)**

Three design choices change everything:

1. **The interval:** usually 15 minutes. Your kW reading is the average draw over that interval, so a brief surge counts less than a sustained one.
2. **The window:** all hours, or only on-peak hours. A peak at 2 a.m. matters only if the window covers it.
3. **The reset:** a new peak each day, or one peak for the whole billing period. With a monthly peak, one bad 15 minutes costs you all month.

## Example 1: Colorado Springs Utilities (Approved 2026)

Colorado Springs Utilities' new demand-charge option for solar customers, approved by City Council on September 22, 2026, uses:

- **Interval:** 15 minutes.
- **Window:** on-peak, 5 p.m. to 9 p.m., Monday to Friday.
- **Reset:** the highest interval in the billing period.
- **Rate:** $0.3608 per kW per day in summer, $0.2462 in winter.

| Highest on-peak 15-minute demand | Summer, 30-day month | Winter, 30-day month |
|---|---|---|
| 3 kW | $32.47 | $22.16 |
| 5 kW | $54.12 | $36.93 |
| 7 kW | $75.77 | $51.70 |

The option pairs the demand charge with a low flat energy price of 5.93¢ per kWh (our sum of the listed components) and a fixed $0.8265 a day. Cutting a summer peak from 7 kW to 4 kW saves 3 × $0.3608 × 30 = $32.47 that month. Our [Colorado Springs article](/posts/colorado-springs-utilities-net-metering-changes-2026/) covers both of the utility's new options.

## Example 2: NV Energy, Southern Nevada (Delayed)

Nevada regulators approved a daily residential demand charge for NV Energy's southern territory in September 2025, Utility Dive reported. It is based on the highest 15-minute period of use each day. NV Energy estimated it at about $20 on an average bill and said it changes the structure of the bill rather than raising it. Utility Dive did not report a per-kW rate. The start has since been delayed to January 2027. See our [Nevada rate guide](/posts/nevada-electricity-rate-changes-2026/).

A daily reset is more forgiving than a monthly one: a single spike costs you one day, not the whole month.

## Why Demand Charges Matter for Solar

Solar panels lower the kWh you buy from the grid. A demand charge does not bill kWh. Two things follow:

- **When per-kWh prices fall to make room for a demand charge, each solar kWh offsets less.** Under Colorado Springs' demand option the energy price is 5.93¢. Under its grid access option, summer on-peak energy costs 35.66¢.
- **Your peak usually comes when solar is weakest.** A weekday 5 p.m. to 9 p.m. window starts as production falls and ends after sunset. Cooking, laundry, air conditioning and EV charging cluster then.

The result: a solar home on a demand rate gets less from its panels and more from managing evening load.

## How to Lower a Demand Charge

1. **Stagger big loads.** Don't run the dryer, oven, dishwasher and EV charger in the same 15 minutes during the peak window.
2. **Move flexible loads out of the window.** Charge an EV after 9 p.m. or midday. Run laundry on weekends where weekends are off-peak.
3. **Pre-cool or pre-heat** before the window starts.
4. **Use a battery during the window.** Even a modest battery can cap the grid draw that sets the charge.
5. **Check a load controller or smart panel** that can hold off one appliance while another runs.
6. **Read your interval data.** Most smart-meter utilities let you see 15-minute or hourly use online. Find your actual peaks before buying equipment.

## Questions to Ask Your Utility or Installer

- Is my rate demand-based now, or will it be? Is the demand option voluntary?
- What interval, window and reset does it use?
- What is the rate per kW, and is it daily or monthly?
- Does the solar savings estimate include the demand charge? What peak did it assume?
- How much would a battery of a given size reduce my peak?

## Limitations

- Residential demand charges are still uncommon, and their designs vary. The two examples are illustrations, not a survey.
- The Colorado Springs rates are as listed on the utility's page, which says its bill estimate uses 2027 rates. The NV Energy details come from news reporting and our earlier Nevada research, not the commission order.
- Monthly figures use a 30-day month.

## Sources

- [Colorado Springs Utilities, "Approved changes for solar customers"](https://www.csu.org/solar-energy-program/net-metering-changes)
- [Utility Dive, "Regulators approve demand charge, net metering changes for NV Energy," September 18, 2025](https://www.utilitydive.com/news/regulators-approve-demand-charge-net-metering-changes-for-nv-energy/760485/)
- [KTVN 2 News, "NV Energy to implement changes to solar energy billing and demand charges"](https://www.2news.com/news/local/nv-energy-to-implement-changes-to-solar-energy-billing-and-demand-charges/article_1f692cb9-f297-4af4-9b7e-25a8fefbcbdf.html)

## Frequently asked questions

### What is a residential demand charge?

A charge based on the highest amount of power your home draws at one time, measured in kilowatts (kW) and usually averaged over 15 minutes, rather than the total energy you use over the month in kilowatt-hours (kWh).

### What is the difference between kW and kWh?

kW measures how fast you use power at a moment. kWh measures how much you use over time. Running a 5 kW load for two hours uses 10 kWh. A demand charge bills the kW; an energy charge bills the kWh.

### Do solar panels reduce demand charges?

Sometimes, but often not much. A demand charge is set by your single highest interval. If that peak comes in the evening, when panels produce little, solar does not lower it. Shifting loads or a battery can.

### Which utilities charge homes a demand charge?

It is still uncommon for homes. Examples include an optional demand-based rate for solar customers at Colorado Springs Utilities, approved in September 2026, and a daily residential demand charge NV Energy got approved for Southern Nevada, now expected in January 2027.


Image credit: Photo by Point3D Commercial Imaging Ltd. on [Unsplash](https://unsplash.com/photos/a-laundry-room-with-a-washer-and-dryer-iPYwrj2CZxE?utm_source=solarexaminer&utm_medium=referral)