Solar or Electric Attic Exhaust Fans?

I live in Dallas Texas an as we know it get hot here early.

I have a 3000 home with large pitch roof. I currently have (older)
electric exhaust fans & looking to replace with solar ones. I am just
not sure that the solar can pull enough heat out of the attic to help.

I first looked at just replacing the current electric fans with newer
ones that draw less amps when running. Currently they pull 5.1 amps.
(I have two electric fans now) From what I can tell so far the newer
electric exhaust fan only pull about 2.9.

Does any one in the Dallas Texas area have these installed? Do they
work as well as the electric? Would you recommond one over the other?

Look at the cfm ratings for them and you'll see that the solar powered ones
are not rated as high as the normal electric ones... You'll need to add more
of them to get the same cooling effect... You'll also lose cooling effect
after the sun goes down... As us Texans know, our roofs stay hot for quite a
bit even after the sun goes down...

Any suggestions would be helpful.