Quick answer: A modern 400W solar panel produces about 1. residential median of 5 peak sun hours. Formula used: Daily kWh = (Panel Wp × Number of panels × Peak Sun Hours × (1 − derate)) ÷ 1000. Default derate is the percentage losses (inverter, wiring, temperature. The average solar panel output per day depends on several factors, such as location, weather, panel orientation, and shading. Over the course of a sunny day, this translates into approximately 1. 8 kWh of power daily, depending heavily on where you live and the season. 83 by NREL PVWatts v8 default — or 0. 75 Factor: Accounts for 25% system losses (inverter efficiency, wiring, battery storage). Divide by 1000: Converts watt-hours (Wh) to kilowatt-hours (kWh).
