Enter your system size, peak sun hours, and efficiency to calculate daily kWh output, annual savings, CO₂ offset, and a month-by-month production estimate. Was this calculator helpful? Input the total installed capacity of your solar array in kilowatts (kW). residential median of 5 peak sun hours. A 10 kW system produces about 42 kWh/day. Core idea: Generation is irradiance-driven energy over time, not just panel nameplate wattage. Formula used: Daily kWh = (Panel Wp × Number of panels × Peak Sun Hours × (1 − derate)) ÷ 1000. Default derate is the percentage losses (inverter, wiring, temperature. Estimate daily, monthly, and yearly solar energy output (kWh) based on panel wattage, quantity, sunlight hours, and efficiency factors. Typical total efficiency ranges 75–90%. Increasing panel count or choosing higher wattage. Estimate daily & annual energy generation based on your panel specs, location, and system setup * Values shown before system losses (inverter, wiring, temperature).