How Many Solar Panels Do You Need to Power a House? 2026 State-by-State Guide
The average American home uses 886 kWh per month and needs approximately 20-25 solar panels (an 8-10 kW system) to offset 100% of electricity use. However, the exact number varies dramatically by location — a home in Arizona may need only 16 panels, while the same home in New York could need 28. The key factors are your monthly electricity usage, local peak sun hours, panel wattage, and system efficiency.
The Sizing Formula
The fundamental formula for solar system sizing is: System Size (kW) = Monthly kWh ÷ (Peak Sun Hours × 30 × System Efficiency). For the average US home: 886 kWh ÷ (4.5 × 30 × 0.80) = 8.2 kW. At 400W per panel, that's 8,200 ÷ 400 = 21 panels. The 0.80 efficiency factor accounts for inverter losses, temperature derating, wiring losses, and panel degradation.
Solar Panels Needed by State
The number of panels varies significantly by state due to different sun exposure. Arizona averages 6.5 peak sun hours and needs only 16 panels. California averages 5.8 hours and needs 18 panels. Texas at 5.3 hours needs 20 panels. Florida at 5.5 hours needs 19. New York with only 3.6 peak sun hours needs 28 panels. Ohio at 3.7 hours needs 27. This demonstrates why location is the single biggest factor in solar sizing. Use our Solar Panel Calculator for your specific state.
Solar Panel Cost in 2026
The average cost of a residential solar system in the US is $2.50-$3.50 per watt before incentives. For an 8-10 kW system, that's $20,000-$35,000 gross. The 30% federal Investment Tax Credit (ITC), extended through 2032 under the Inflation Reduction Act, reduces cost by 30%. Additional state incentives, SRECs, and utility rebates can further reduce the net cost. After all incentives, most homeowners pay $14,000-$22,000 for a complete system.
Step-by-Step Sizing Process
1. Check your electric bill for average monthly kWh (look at 12-month history). 2. Find your peak sun hours at pvwatts.nrel.gov or use our state-specific calculator. 3. Apply the formula: Monthly kWh ÷ (Sun Hours × 30 × 0.80). 4. Divide by panel wattage (400W standard 2026) for panel count. 5. Check roof space: each 400W panel needs about 20 sq ft. 6. Get 3+ quotes from certified installers — prices vary 30-50% by company.
| State | Peak Sun Hrs | Panels (886 kWh) | System kW | Est. Cost (After ITC) |
|---|---|---|---|---|
| Arizona | 6.5 | 16 | 6.4 kW | $11,200 |
| California | 5.8 | 18 | 7.2 kW | $12,600 |
| Texas | 5.3 | 20 | 8.0 kW | $14,000 |
| Florida | 5.5 | 19 | 7.6 kW | $13,300 |
| Colorado | 5.6 | 19 | 7.5 kW | $13,100 |
| North Carolina | 4.7 | 22 | 8.9 kW | $15,500 |
| New York | 3.6 | 28 | 11.3 kW | $19,700 |
| Ohio | 3.7 | 27 | 10.9 kW | $19,100 |
Do You Need to Offset 100% of Usage?
Not necessarily. Many homeowners choose to offset 80-90% of usage, which significantly reduces the system size and cost while still providing most of the savings. With net metering, any excess production during summer months can offset higher winter usage. Battery storage (like Tesla Powerwall at $11,500) adds backup power but is not required for grid-tied systems. Use our Solar ROI Calculator to find the optimal system size for your budget.
Disclaimer: This article is for educational reference only. Consult a licensed professional for all electrical work and solar installations.