At full sun, it makes 400 watts. 6 to 2 kWh, depending on conditions. Free solar panel power calculator to estimate energy and power output. It starts off with the following equation: Where: electricity consumption (kWh/yr) – Total average amount of electricity you use annually. Found on your utility bill, and solar hours per day – Average hours of direct. Estimate daily, monthly, and yearly solar energy output (kWh) based on panel wattage, quantity, sunlight hours, and efficiency factors. Simply enter the battery specifications, including Ah, volts, and battery type. Compute array Vmp/Voc and Imp/Isc from a panel's datasheet values.