Solar Panel Calculator
Calculate how much electricity your solar panels generate based on panel wattage, count, and sun hours.
How It Works
Enter your panel wattage, number of panels, and average peak sun hours for your location. The calculator shows daily and monthly generation and the percentage of your bill it could cover.
Formula
Daily kWh = Panel Watts x Number of Panels x Peak Sun Hours / 1000
Frequently Asked Questions
What are peak sun hours?
Peak sun hours are hours of sunlight equivalent to 1000 W/m2. The US average is 4-6 hours. Desert Southwest gets 6-7; Pacific Northwest gets 3-4. Check NREL's solar maps for your location.
How many panels do I need?
Divide your monthly kWh by (panel wattage x peak sun hours x 30 / 1000). For 900 kWh/month with 400W panels and 5 sun hours: 900 / (0.4 x 5 x 30) = 15 panels.