A typical US home needs 15–25 solar panels (6–10 kW system) to offset 100% of electricity.
Average solar installation cost: $2.50–$3.50 per watt. A 8kW system: $20K–$28K before incentives.
Divide monthly kWh by (panel wattage × sun hours × 30 × 0.8 efficiency). Avg US home: 15–25 panels.