Solar panels in Rapid City, SD
Roofs in Rapid City get about 1,734 hours of usable sunlight a year — more than 76% 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 Rapid City → City averages are a starting point; your own roof's size, pitch and shading change the answer a lot.
What a typical Rapid City solar system costs
A 19-panel system (7.6 kW) is about right for an average Rapid City home using 10,800 kWh a year. It would produce roughly 11,202 kWh annually and offset 100% of that usage.
| System | Size | kWh/yr | Net cost | Saves/yr | Payback |
|---|---|---|---|---|---|
| 8 panels | 3.2 kW | 4,716 | $6,384 | $580 | 11 yrs |
| 12 panels | 4.8 kW | 7,075 | $9,576 | $870 | 11 yrs |
| 16 panels | 6.4 kW | 9,433 | $12,768 | $1,160 | 11 yrs |
| 20 panels | 8 kW | 11,791 | $15,960 | $1,359 | 11.7 yrs |
| 26 panels | 10.4 kW | 15,329 | $20,748 | $1,468 | 14.1 yrs |
How we worked this out for Rapid City
Every number on this page comes from these seven steps. Nothing is a national average — the sunlight figure is measured from Rapid City rooftops.
| # | Step | Result |
|---|---|---|
| 1 | What one panel makes here 400W ÷ 1000 × 1,734 sun hrs × 0.85 system losses |
590 kWh/yr |
| 2 | Panels needed to cover typical usage 10,800 kWh ÷ 590 kWh per panel |
19 panels |
| 3 | System size 19 panels × 400W |
7.60 kW |
| 4 | Annual production 7.60 kW × 1,734 hrs × 0.85 |
11,202 kWh/yr |
| 5 | Installed cost 7,600 W × $2.85 per watt, then −30% federal credit |
$15,162 |
| 6 | Annual saving 3,780 kWh used as generated × 12.3¢ + 7,422 kWh exported × 12.3¢ |
$1,341/yr |
| 7 | Payback $15,162 ÷ $1,341 per year |
11.3 years |
Step 6 matters more than it looks. Only 34% of what a system this size produces in Rapid City is used the moment it is generated; the other 7,422 kWh is exported and credited one-for-one under net metering. Because exports here are credited at or near retail, that split changes the payback very little — 11.0 years against the 11.3 we show. In places where exports pay a fraction of retail the same split moves payback by years, which is why we model it explicitly rather than assuming.
Assumptions: 400W panels, 15% system losses (inverter, wiring, heat, soiling), $2.85/W installed, 10,800 kWh typical annual household use, 12.3¢/kWh electricity. Change any of those and every figure above moves — which is exactly why a single national "solar costs X" number is misleading.
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 Rapid City gets 1,734 sun hours
That figure comes from Google's analysis of real rooftops across Rapid City — 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 Rapid City reaches about 1,745 hours, roughly 1% better than typical.
The numbers behind this page
| Typical usable sunlight | 1,734 hrs/yr |
|---|---|
| Unshaded roof | 1,745 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 | 8 |
| Google imagery from | 2012 |
When Rapid City actually produces
Annual totals hide the thing that catches people out: 38% of Rapid City's yearly sunlight arrives in May–July, and just 12% across November–January.
| Month | Sun hrs | Share of year |
|---|---|---|
| Jan | 69 | |
| Feb | 98 | |
| Mar | 138 | |
| Apr | 181 | |
| May | 212 | |
| Jun | 226 | |
| Jul | 219 | |
| Aug | 193 | |
| Sep | 153 | |
| Oct | 110 | |
| Nov | 75 | |
| Dec | 61 |
Rapid City produces about 3.7× 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 Rapid City's latitude, not separately measured, so treat the monthly figures as the shape of a typical year rather than a forecast.
How Rapid City compares to the other 788 cities
| Measure | Rapid City | Rank of 788 |
|---|---|---|
| Usable sunlight | 1,734 hrs | 188th |
| Sunlight lost to shade | 1% | 780th most |
| Median roof size | 199 m² | 371st largest |
| Electricity rate | 12.3¢ | 666th highest |
| Payback | 11.3 yrs | 467th fastest |
| Grid carbon | 770 kg/MWh | 179th dirtiest |
What actually stands out about Rapid City:
- Unusually open roofs. Only 1% of available sunlight is lost to obstruction in Rapid City — better than all but 8 of the 788 cities measured. Most roofs here get close to their theoretical maximum.
- Sunnier than the rest of South Dakota. Rapid City roofs get 10% more usable sunlight than the typical South Dakota city we've measured — statewide averages will understate what you can expect here.
- Older imagery. Google's aerial capture of Rapid City dates from 2012. Tree growth and new construction since then are not reflected.
Cities with almost the same sunlight
These are the closest matches to Rapid City's 1,734 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 |
|---|---|---|---|
| Hialeah, FL | 1,734 | 15.3¢ | 9.1 yrs |
| Kenner, LA | 1,732 | 12.1¢ | 11.5 yrs |
| Manhattan, KS | 1,736 | 14.1¢ | 9.9 yrs |
| Stillwater, OK | 1,732 | 12.1¢ | 11.5 yrs |
Nearby cities
See all of South Dakota → statewide sunlight, rates, incentives and every city we've measured.
Rapid City solar questions
How many solar panels do I need in Rapid City?
About 19 panels for an average home using 10,800 kWh a year. Rapid City roofs get 1,734 usable sun hours, so each 400W panel produces roughly 590 kWh annually. A typical Rapid City roof fits about 64 panels, so roof space is unlikely to be your limit.
Is solar worth it in Rapid City?
At 12.3¢/kWh and 1,734 sun hours, a typical system pays for itself in about 11.3 years and returns roughly $18,357 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 Rapid City?
A 7.6 kW system costs about $21,660 before incentives and $15,162 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.