Solar panels in Rapid City, SD: payback and output
A kW of south-facing panels in Rapid City produces about 1,460 kWh a year, 4% more than Sioux Falls, the South Dakota reference city. Summer months produce 1.9× what winter does. To cover a typical 10,500 kWh/yr home on paper you'd need roughly 7.2 kW.
Output by month in Rapid City (kWh per kW)
Best: May · weakest: Dec.
Example 7 kW system in Rapid City
- Installed cost (example)
- $21,000
- Production, year 1
- 10,219 kWh
- Savings, year 1
- $1,571
- Payback
- 12.6 years
- 25-year net gain
- $26,727
Uses the South Dakota average price (15.37¢/kWh, EIA July 2026), full net metering and no incentives. Your utility's rate and export credit may differ — change them below.
Roof direction in Rapid City
Yearly output per kW of panels at a 20° pitch, and how it compares with a south-facing roof.
| Roof faces | kWh per kW/yr | vs. south |
|---|---|---|
| South | 1,460 | — |
| Southeast | 1,383 | −5% |
| Southwest | 1,398 | −4% |
| East | 1,206 | −17% |
| West | 1,227 | −16% |
| East-west (split) | 1,216 | −17% |
Calculate your home in Rapid City
Estimated payback
12.6 years
A solid case if you plan to stay in the home.
≈ $131/month off your bill in year 1
- Year-1 savings
- $1,571
- 25-yr net gain
- $26,727
- Return (IRR)
- 6.9%
- Net cost
- $21,000
Cumulative savings minus cost
Production vs. use by month
10,219 kWh/yr
Covers 40% of your use directly; 41% of the output is used on the spot.
Which size pays off best?
Same usage and prices, only size changes. Best 25-year gain: 8 kW.
| Size | Cost | Year-1 savings | Payback | 25-yr gain |
|---|---|---|---|---|
| 3 kW | $9,000 | $673 | 13.6 years | $10,026 |
| 4 kW | $12,000 | $897 | 13.1 years | $14,201 |
| 5 kW | $15,000 | $1,122 | 12.9 years | $18,376 |
| 6 kW | $18,000 | $1,346 | 12.7 years | $22,551 |
| 7 kW | $21,000 | $1,571 | 12.6 years | $26,727 |
| 8 kW | $24,000 | $1,614 | 13.4 years | $28,549 |
| 10 kW | $30,000 | $1,614 | 16.1 years | $22,626 |
| 12 kW | $36,000 | $1,614 | 18.7 years | $16,626 |
Read the full South Dakota solar guide for net metering, orientation and price trends.
Cities with similar sunshine
Solar in Rapid City: common questions
Are solar panels worth it in Rapid City, SD?
For an example 7 kW system costing $21,000 on a home using 10,500 kWh a year, payback in Rapid City is 12.6 years with full net metering and 17.2 years if exports earn half the retail rate, at the South Dakota average price of 15.37¢/kWh (EIA, July 2026).
How much electricity do solar panels produce in Rapid City?
About 1,460 kWh per year for each kW of south-facing panels at a 20° pitch (NLR PVWatts, typical-year weather), from 72 kWh in Dec to 157 kWh in May.
What size solar system does a home in Rapid City need?
About 7.2 kW to cover 10,500 kWh a year. Divide your own annual use by 1,460 kWh per kW for a first estimate; if exports earn less than retail, a smaller system often pays back faster.
Does roof direction matter in Rapid City?
Yes. Per kW at a 20° pitch: south 1,460 kWh, southeast 1,383 kWh, southwest 1,398 kWh, east 1,206 kWh, west 1,227 kWh, east-west (split) 1,216 kWh a year. South-facing roofs produce the most; east or west roofs still work, with less output.
Guides for going solar in Rapid City
- Payback · 4 minIs solar still worth it without the 30% federal tax credit?The 30% federal solar credit is gone for new systems. We ran payback for every state without it, and compared it with what the credit used to do.
- Planning · 3 minHow many solar panels do I need? Sizing from your electric billA step-by-step way to size a home solar system from your annual kWh, daytime use and local sunshine, with real size-vs-payback tables for four states.
- Payback · 4 minNet metering vs. net billing: how export credits change paybackHow much your utility pays for exported solar power can add years to payback. We compare full, half and quarter-retail credits in every state.
- Planning · 6 minEast- or West-Facing Roof: Is Solar Still Worth It?East- or west-facing solar panels made about 14.5% to 14.8% less power than south-facing ones across U.S. states. See where the loss is biggest and smallest.
- Planning · 6 minSolar Panels in Winter: Output by State vs. SummerHow much do solar panels make in winter? Winter vs. summer output per kW for U.S. states, why the gap grows up north, and what it means for net metering.
- Payback · 5 minRising electricity prices: where solar pays back fastestCompare electricity prices and solar payback by state: see where a rooftop system pays back fastest, where it is slowest, and why credit rules matter.
Data: NLR PVWatts v8 (U.S. DOE National Laboratory of the Rockies, formerly NREL), TMY weather near Rapid City (44.08, -103.23), 14% losses, retrieved 2026-10-11. Published 2026-10-15.