Solar panels in Watertown, SD
Roofs in Watertown get about 1,547 hours of usable sunlight a year — more than 50% of the cities we've measured. Here's what that means in cost, savings and payback, using real rooftop data rather than a national average.
Check your specific roof in Watertown → City averages are a starting point; your own roof's size, pitch and shading change the answer a lot.
What a typical Watertown solar system costs
A 21-panel system (8.4 kW) is about right for an average Watertown home using 10,800 kWh a year. It would produce roughly 11,046 kWh annually and offset 100% of that usage.
| System | Size | kWh/yr | Net cost | Saves/yr | Payback |
|---|---|---|---|---|---|
| 8 panels | 3.2 kW | 4,208 | $6,384 | $518 | 12.3 yrs |
| 12 panels | 4.8 kW | 6,312 | $9,576 | $776 | 12.3 yrs |
| 16 panels | 6.4 kW | 8,416 | $12,768 | $1,035 | 12.3 yrs |
| 20 panels | 8 kW | 10,520 | $15,960 | $1,294 | 12.3 yrs |
| 26 panels | 10.4 kW | 13,675 | $20,748 | $1,417 | 14.6 yrs |
Notice that payback barely improves as systems get bigger, and eventually gets worse. That's because you can only save money on electricity you were going to buy anyway. Once a system covers your usage, extra panels mostly generate exports at a much lower rate.
Why Watertown gets 1,547 sun hours
That figure comes from Google's analysis of real rooftops across Watertown — it already accounts for shading from trees, chimneys and neighbouring buildings, which is why it's lower than the raw "hours of daylight" figures you'll see elsewhere. An unusually open, unshaded roof in Watertown reaches about 1,610 hours, roughly 4% better than typical.
The numbers behind this page
| Typical usable sunlight | 1,547 hrs/yr |
|---|---|
| Unshaded roof | 1,610 hrs/yr |
| Electricity rate (South Dakota avg) | 12.3¢/kWh |
| Installed cost assumed | $2.85/W |
| Panel size assumed | 400 W |
| Federal tax credit | 30% |
| Typical household usage | 10,800 kWh/yr |
| Power used as generated | 34% |
| Paid for exported power | full retail (net metering) |
| Rooftops sampled here | 5 |
| Google imagery from | 2017 |
When Watertown actually produces
Annual totals hide the thing that catches people out: 38% of Watertown's yearly sunlight arrives in May–July, and just 11% across November–January.
| Month | Sun hrs | Share of year |
|---|---|---|
| Jan | 59 | |
| Feb | 86 | |
| Mar | 122 | |
| Apr | 162 | |
| May | 191 | |
| Jun | 204 | |
| Jul | 197 | |
| Aug | 173 | |
| Sep | 137 | |
| Oct | 97 | |
| Nov | 66 | |
| Dec | 52 |
Watertown produces about 3.9× as much in Jun as in Dec — a normal mid-latitude swing. Expect real winter shortfall and summer surplus rather than steady year-round output.
The annual total is measured from Google's rooftop imagery. Its split across months is calculated from solar geometry at Watertown's latitude, not separately measured, so treat the monthly figures as the shape of a typical year rather than a forecast.
How Watertown compares to the other 673 cities
| Measure | Watertown | Rank of 673 |
|---|---|---|
| Usable sunlight | 1,547 hrs | 336th |
| Sunlight lost to shade | 4% | 459th most |
| Median roof size | 209 m² | 328th largest |
| Electricity rate | 12.3¢ | 553rd highest |
| Payback | 12.5 yrs | 528th fastest |
| Grid carbon | 832 kg/MWh | 115th dirtiest |
What actually stands out about Watertown:
- Older imagery. Google's aerial capture of Watertown dates from 2017. Tree growth and new construction since then are not reflected.
Cities with almost the same sunlight
These are the closest matches to Watertown's 1,547 usable sun hours from other states and provinces. Same sunlight, different electricity prices — which is usually what decides whether solar is worth it.
| City | Sun hrs | Rate | Payback |
|---|---|---|---|
| Chattanooga, TN | 1,546 | 12.1¢ | 12.8 yrs |
| Bowling Green, KY | 1,548 | 12.2¢ | 12.6 yrs |
| Johnson City, TN | 1,546 | 12.1¢ | 12.8 yrs |
| Atlanta, GA | 1,545 | 14.1¢ | 10.9 yrs |
Nearby cities
See all of South Dakota → statewide sunlight, rates, incentives and every city we've measured.
Watertown solar questions
How many solar panels do I need in Watertown?
About 21 panels for an average home using 10,800 kWh a year. Watertown roofs get 1,547 usable sun hours, so each 400W panel produces roughly 526 kWh annually. A typical Watertown roof fits about 67 panels, so roof space is unlikely to be your limit.
Is solar worth it in Watertown?
At 12.3¢/kWh and 1,547 sun hours, a typical system pays for itself in about 12.5 years and returns roughly $16,641 over a 25-year panel life. That is slower than average, so compare several quotes before committing. Exported power earns full retail credit here.
How much do solar panels cost in Watertown?
A 8.4 kW system costs about $23,940 before incentives and $16,758 after the 30% federal tax credit. That works out near $2.85 per watt installed. Roof pitch, shading, electrical panel upgrades and equipment choice move the price most, which is why quotes for the same house can differ by thousands.
Worth reading before you buy
Estimates only, generated 2026-08-22 from Google Solar API rooftop samples and average South Dakota electricity rates. Not a quote and not financial advice. Your roof, usage, utility plan and local incentives will change these numbers — get real quotes before buying.