Solar Panel Calculator
Calculate how many solar panels you need or how much energy your panels can generate. Supports home, RV, and camping setups with US sun region data.
Frequently Asked Questions
How is daily energy production calculated?
Daily energy (kWh) = Number of panels × Panel wattage (kW) × Peak sun hours × (1 - System loss %). For example, 10 panels at 400W with 5 sun hours and 15% losses = 10 × 0.4 × 5 × 0.85 = 17 kWh/day.
What are peak sun hours?
Peak sun hours represent the equivalent number of hours at full 1,000 W/m² solar irradiance. A location may have 12 hours of daylight but only 5 peak sun hours because morning and evening sunlight is less intense. This varies by location and season.
What does system loss percentage mean?
System losses account for real-world inefficiencies: inverter conversion (3-5%), wiring resistance (1-2%), panel temperature derating (5-10%), shading, dirt, and aging. A typical total loss of 15% is used as the default.
How do I size a battery storage system?
To store one full day of solar production, divide your daily kWh output by the battery capacity. A Tesla Powerwall stores 13.5 kWh, so a 30 kWh/day system needs about 2.2 Powerwalls for full-day backup. Most homes only need enough for overnight use (about 10-15 kWh).