Free online solar panel output calculator — estimate daily, monthly, and yearly kWh energy production based on panel wattage, number of panels, sun hours, and system efficiency. That's the wattage; we have 100W, 200W, 300W solar panels, and so on. How much solar energy do you get in your area? That is determined by average peak solar hours. South. System Voltage (12V, 24V, 48V): This is the operating voltage of your battery bank. For smaller systems (like RVs or camping), 12V is common. Higher voltage systems carry the same amount of power. Batteries are now cheap enough to unleash solar's full potential, getting as close as 97% of the way to delivering constant electricity supply 24 hours across 365 days cost-effectively in the sunniest places. Losses come from inverter efficiency, wiring, temperature, and dirt. Daily Power Consumption:.