How much sun is needed to power the solar power fans?

The solar panel of the solar power fan needs direct sunlight to convert enough energy to spin the fan.

The solar panel needs direct sunlight to convert enough energy to spin the fan. When subjected to direct sunlight, the solar panel should generate approximately 21.0 to 22.0 volts DC. With indirect sunlight or when the sun is going down, the voltage will fall below 20 VDC. A minimum of 0.1 Amps DC is needed to turn the fan, which requires that the solar panel be directed in the general direction of the sun (20 Volts is not required to turn the fan if sufficient amperage is supplied; this is why a 12V battery can be used to test the motor). Air Vent recommends a southern or southwestern exposure and that the panel be tilted from horizontal at an angle equivalent to 20 degrees plus the latitude value of the specific site location.