[villagetinker]

I would ask about the CFM (cubic feet per minute) rating of the SOLAR fan versus an 120 volt AC powered fan. There will be a cost for the new AC supply, if you are lucky the supply for the attic light can be tapped for the new fan. There will be a cost to cut the hole in the roof for the vent (should be the same for either type of installation). I would opt for a thermostatic control on the AC powered fan this will allow it to turn on when needed and run until the attic is cooled off. Finally, look at the costs, installed and running, unless you put in a really big AC powered fan, the cost will probably be 10 to 20 cents per day, while the solar is free, however the installed costs between the 2 options maybe significant.