With average irradiance  a solar panel will normally produce 4 watt-hours (Wh) per day for 1 watt of watts.

With average irradiance of 4 peak sun hours a 1 square meter solar panel will produce 1460kWh/year.

The average solar panel will produce 136kWh/yr per square foot.

Complete cloud cover could reduce output by 90%, while passing clouds might reduce output by between 20 to 50%.

Solar panels produce as little as 25 to 35% of summer power production, depending on location.

Calculating how much power your solar panels can produce.