This is a North American (USA) Solar Insolation Map showing the amount of solar energy in hours (peak sun hours) received each day on an optimally tilted surface during the worst month of the year. Based on accumulated solar insolation data.
Look on the map to find your location and the amount of hours of peak solar insolation. The dotted lines are the middle of the zone.
The map below is a worse case insolation map.
Click Image to enlarge (Opens in a new window)