Run an extension cord from your house to the coop.
I am very dubious about running household electric equipment into an agricultural environment.
A home use fan is not designed to cope with the level of dust that chickens generate and is very likely to end up conking out -- if you're lucky -- or shorting out and causing a fire -- if you're not lucky.
There are fans made for agricultural and industrial conditions, but it might be easier to add additional natural ventilation to a stuffy coop than to install fan and electric safely.
