How Many Solar Panels Do I Need? Calculator for Any US State
Most US homes need roughly 6–10 kW, about 15–25 panels; enter your monthly bill or kWh and pick your state for size, panel count and roof area.
· Source: EIA Electric Power Monthly Table 5.6.A (July 2026 data) · next EIA update ~Oct 23
On this page: CalculatorTableHow we calculatedSources
Jump to calculator ↓Secondary control: the slider nudges the rate field above (numeric input stays the precise, primary way in). The URL keeps your scenario.
Why this number
Bigger isn’t better in 2026 — right-size to your actual usage. Enter your numbers:
How to read the result
- System size (kW) — the total capacity you’d install.
- Panels — size ÷ panel wattage (this tool assumes modern ~400 W panels).
- Roof area — panel area (a 400 W module is about 21.5 sq ft) multiplied by roughly 1.4 to allow for fire setbacks, walkways and obstructions. Quoting bare panel area understates the roof you actually need by around 40%, which is how homeowners conclude a roof fits when it does not. Real layouts depend on roof shape and orientation.
Want the panel count behind that size? See how many solar panels you need . Once you know your size, estimate the cost and payback in the 2026 savings calculator , check cost by state , and read how much solar costs in 2026 .
Starting from square footage instead? The house-size cost table brackets 1,000-4,000 sq ft homes from RECS usage bands — then come back here with a real bill.
Frequently asked questions
How many solar panels does an average home need?
Most homes need about 15–25 panels (roughly a 6–10 kW system) to offset their usage, depending on how much electricity they use and how much sun the roof gets. Enter your own bill above for a personalized estimate.
How is system size calculated?
Your annual kWh usage divided by how much a 1 kW system produces per year (about 1,200 kWh on a US average; more in sunny states, less in cloudy ones). That gives kW; divide the watts by your panel wattage (~400 W) for panel count.
Should I oversize my solar system in 2026?
Usually no. Without the federal credit, extra panels you don’t need just add cost and lengthen payback — especially under net billing, where exporting surplus power pays little. Size to your usage, not above it.
How we calculated this
System size (kW) = annual kWh ÷ (your state’s kWh-per-kW production band × the share of usage you want to offset). Panel count = size × 1,000 ÷ panel watts, rounded up. Roof area = panels × the per-panel area you enter. Production bands are modeled from PVGIS/NSRDB irradiance for each state, listed on the state pages.Sources: U.S. Energy Information Administration (EIA) electricity rates · DSIRE incentive records · public IRS/OBBBA guidance. Figures are modeled estimates, not quotes or tax advice. See our methodology.