In short: Watertown has about 23,500 people and sits in Codington County. NorthWestern Energy, Watertown Municipal Utilities and Otter Tail Power Co serves different parts of Codington County, so your utility depends on your address; their 2024 home averages range from 9.3¢ to 12.56¢ per kWh (EIA). FEMA rates Codington County ice storms “relatively high”. Rooftop solar here makes roughly 1,190 kWh a year per kW of panels by our estimate, which is about average for the U.S..
This page covers what is local to Watertown: its utility, outage records, sunshine, weather risks and charging. Statewide rules such as net metering, incentives and electrician licensing are in our South Dakota energy guide.
Watertown at a glance
- Place: Watertown, Codington County, South Dakota; about 23,492 residents (Census Bureau estimate, July 2024).
- Utility: NorthWestern Energy (investor-owned). Homes paid an average 12.56¢ per kWh in 2024 (EIA-861); the average customer lost 66 minutes of power on normal days, with 0.6 interruptions a year (utility-wide, not just Watertown).
- Utility: Watertown Municipal Utilities (city-owned). Homes paid an average 9.3¢ per kWh in 2024 (EIA-861); the average customer lost 3 minutes of power on normal days, with 0.1 interruptions a year (utility-wide, not just Watertown).
- Utility: Otter Tail Power Co (investor-owned). Homes paid an average 10.93¢ per kWh in 2024 (EIA-861); the average customer lost 71 minutes of power on normal days and 135 counting major storms, with 1.0 interruptions a year (utility-wide, not just Watertown).
- Sun: 4.08 kWh per square meter per day on average, from 1.45 in December to 6.74 in July (NASA POWER). Our rough estimate: about 1,190 kWh a year per kW of panels.
- Climate: about 670 cooling degree-days and 7,990 heating degree-days a year (base 65°F, NASA POWER), so heating is the big load.
- Top hazards in Codington County: ice storms “relatively high”, winter weather “relatively high” and cold waves “relatively moderate” (FEMA National Risk Index; overall county risk rated “relatively low”).
- Public charging: 27 ports at 5 locations in Watertown, 24 of them DC fast (AFDC, October 20, 2026).
Your utility and what it means
NorthWestern Energy is an investor-owned utility and served about 51,467 home customers in 2024; its 12.56¢ average was below the 15.37¢ statewide average for July 2026. Watertown Municipal Utilities is a city-owned utility and served about 11,633 home customers in 2024; its 9.3¢ average was below the 15.37¢ statewide average for July 2026. Otter Tail Power Co is an investor-owned utility and served about 9,048 home customers in 2024; its 10.93¢ average was below the 15.37¢ statewide average for July 2026. Those are utility-wide averages, not a quote for your address; your own bill is the real number.
For reliability, Otter Tail Power Co reported 71 minutes per customer without major storms in 2024, more than the statewide figure of 62 (EIA-861). Utility-wide numbers hide a lot: a home at the end of a long rural line usually has more outages than the average.
Net metering, export rates and incentives are set at state level and by each utility. Start with the South Dakota guide and then ask your utility for its current interconnection steps before you sign anything.
Backup power in Watertown
- Ice storms (relatively high): Ice storms bring down lines for days. A standby generator with a transfer switch, or a battery sized for the fridge, furnace blower and well pump, matters more than a small power station.
- Winter weather (relatively high): Winter storms and cold snaps combine outages with heating demand. Plan for the furnace blower or heat pump, not just lights, and keep a fuel supply you can reach in snow.
- Heating load: a winter outage can stop a furnace blower, boiler pump or heat pump. List what your heat needs to run before choosing a generator or battery.
- Short outages: a portable power station covers phones, Wi-Fi, a CPAP and lights; a home battery switches over automatically.
Size your setup with the generator sizing tool and the battery backup calculator, and compare options in backup power. Generator safety (CPSC): outdoors only, at least 20 feet from the house, exhaust away from doors and windows, never in a garage, and battery-powered carbon monoxide alarms inside. A licensed electrician should install any transfer switch, with a permit; see generator installation.
Solar in Watertown
By our rough estimate each kW of panels makes about 1,190 kWh a year in Watertown (NASA sunshine data times 365 days times 0.80 for system losses). Valued at NorthWestern Energy’s 2024 average of 12.56¢, that is about $149 a year per kW if all of it offsets your own use (an estimate, not a promise). Production swings with the seasons: July is the sunniest month at 6.74 and December the dimmest at 1.45, a 4.6-to-1 gap, so a battery or a bigger system helps in winter.
Check your own roof with the solar potential tool, see solar costs and net metering vs net billing, and read the steps in solar installation.
Batteries and EV charging
A home battery earns its place when outages are frequent, when your utility pays little for exported solar, or when evening prices are high; compare in home batteries and battery costs. Watertown has 27 public charging ports in the federal station list including 24 DC fast, but home charging is cheaper and easier: see the EV charging cost calculator and EV charger installation.
Drive on another fuel? See every alternative fuel station in Watertown: hydrogen, propane, natural gas, E85 ethanol, biodiesel and renewable diesel.
Permits and inspections
Solar, generator transfer switches and EV chargers normally need an electrical permit from the Watertown building or permitting department, or from Codington County if you live outside city limits, and often a utility interconnection approval. We have not verified a local permit page for Watertown, so check the city and county websites or ask your electrician, who will know the process. Hire only a licensed electrician or installer; the South Dakota guide lists the state licensing rules.
Nearby guides
More local guides: see all of South Dakota, or the whole South Dakota energy guide.
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Watertown energy FAQ
Who is my electric company in Watertown?
NorthWestern Energy, Watertown Municipal Utilities and Otter Tail Power Co all serve parts of Codington County. Which one serves you depends on your street, so check the top of your bill. Their 2024 home price averages differ (NorthWestern Energy 12.56¢, Watertown Municipal Utilities 9.3¢, Otter Tail Power Co 10.93¢) so it matters for solar math.
How much power will solar make in Watertown?
About 1,190 kWh a year per kW of panels by our estimate, so a 6 kW system would make roughly 7,140 kWh. Shade, roof direction and tilt change this; run your address through the solar potential tool for a better number.
Is a generator or a battery better for ice storms in Codington County?
It depends how long the outage lasts. A battery is quiet, automatic and good for short outages and for pairing with solar; a standby generator keeps going as long as it has fuel, which suits multi-day events. Many homes use a battery for everyday outages and add a generator for the rare long one.
Will a home battery keep my heat on in an outage?
It can keep a furnace blower, boiler pump or a heat pump running for a while, but long cold outages drain a battery fast without solar to recharge it. Pair it with a generator or wood or propane heat if outages here run for days.
Do I need a permit for solar or a generator in Watertown?
Almost always an electrical permit for a transfer switch, solar or an EV charger, issued by the city or county where you live. Your licensed electrician or installer normally pulls it. Never connect a generator to your house wiring without a transfer switch.
Sources: EIA Form 861 (2024) for utility prices and outages; NASA POWER climatology (2001 to 2025) for sun and degree-days; FEMA National Risk Index for county hazards; AFDC station locator for public charging; Census Bureau for population. Estimates are ours and are not promises; see our editorial policy. Prices and programs change, so check each program page.