Popularity of Solar Barricade Lights

When driving past construction, I doubt the average person looks closely at the type of barricade light attached to the overwhelming amount of traffic barrels.  Because of my interest in the traffic safety industry, however, I like to see what brand and what type it is.  I am surprised to see that 70% of the time these are solar barricade lights.

I would never think they would be so popular because they are about twice the cost of battery operated barricade lights.  But, they are ‘green’ and you do not need to have batteries or worry about going out and changing the batteries.