The fan that is best for solar system is a 12 volt fan that runs directly off of the DC voltage and so you don't have to convert the DC to AC.
When you convert the DC to AC to power an AC fan the battery power is drained faster than it would if you just used a 12 volt DC fan.
The DC to AC converter also uses power from the battery so you will require more battery power to power the AC fan off the DC to AC converter.
Although you can still power an AC fan off the DC solar system with a converter if you need too but the batteries will drain faster.
You can also buy solar rechargeable fans that have a built in battery and power it with a solar panel.
A good solar powered fan is the 14" solar rechargeable floor fan for outdoors with a 15600mAh battery and has a 20w solar panel that powers the fan.
You can buy the solar powered fan on Amazon.
You can also buy other indoor floor fans on eBay that can be kept charged and powered by solar panels that it comes with.