One of the causes of polarity is the unequal forces of the dipole forces due to differences in electronegativity. The more electronegative molecule tend to attract electrons, hence the polarity arrows point towards it. The electronegativity of Phosphorus and Fluorine is 2.19 and 3.98, respectively. Thus, it points outward towards the fluorine atoms.
Answer: The Wind Fluctuates. Wind energy has a similar drawback to solar energy in that it is not constant. Wind Turbines Are Expensive. Although costs are reducing, wind turbines are still very expensive.