48" 716W Metal Halide System Advance Plus

[The Grizz]

I have 2 of the older style that don't have individual reflectors & the cooling fans are also external on top of the fixture. I have been running them for about 6 months now & only had an issues with the t5 ballasts, which they have changed for better one on the fixture you are looking at. I do know that the cooling fans in this one are a little stronger and the ballasts are better quality but in your case I would suggest not to put the ballast in the window because the sun light will heat them up even more then they already do. Mount them on a board and get a fan like this one to blow on them when there on. Also get a couple more of these type of fans to blow across the bottom of the fixture and top of the tanks to reduce the heat above the tank.

http://www.caudata.org/cc/articles/cooling.shtml

Scroll down the page a bit to find the fan pic.