Our solar irradiance calculator provides estimated W/m² readings, hourly charts, monthly averages, and solar panel optimization tools for solar energy planning. Enter a city name, latitude and longitude, or click the GPS button to use your current position. In the US, for example, we get, on a 12-month average, anywhere from 3 peak sun hours (think Alaska) to 7 peak sun hours (think Arizona, New Mexico). In California and Texas, where we have the most solar panels installed, we. . Estimate daily, monthly, and yearly solar energy output (kWh) based on panel wattage, quantity, sunlight hours, and efficiency factors. Losses come from inverter efficiency, wiring, temperature, and dirt. Input your solar panel system's total size and the peak sun hours specific to your location, this calculator simplifies. . Daily solar production depends on three key factors: Solar Panel Capacity: Measured in kilowatts (kW) or megawatts (MW), it represents the maximum output of your solar panels under ideal conditions.