Most residential solar panels have a power output of around 250-400 watts, and can produce up to 2. 5 kilowatt-hours of electricity per day. Why don't those numbers add up? Because a solar panel only produces energy when the sun is out, so we can't multiply 400 by 24 to determine its. How much solar power can you generate based on your roof size? In a perfect world, the average roof in the U. But also, the world isn't perfect. Realistically, your roof's solar. Most common solar panel sizes include 100-watt, 300-watt, and 400-watt solar panels, for example. How Much Sun Do You Get (Peak Sun Hours). A 400-watt panel can generate roughly 1. household's 900 kWh/month consumption, you typically need 12–18. 1 kilowatt (kW) is equal to 1,000 watts, just as 1,000 watt-hours (Wh) equal 1 kilowatt-hour (kWh).