[Toymeister]

How does this apply to solar?

First, it runs six months that you don't need it.

Second, solar panels which operate the fan, 100% speed (air movement) at 100% Sun but less than 80%at 80% sun or any other sunlight percentage/air movement ratio. So as the peak solar generation hours pass you need your fan but it isn't operating at 100%

Third. solar fans are more expensive

Fourth. Electric fans are cheap to operate

Fitth, Solar fans inflate how much air the move. Think about it solar fan firms claim that a solar fan driven by 20 watts moves as much of more than the most efficient electric fan at five times the wattage.