How noisy is the fan? My neighbor disconnected his as it was loud

If I weren't going to store things in the attic, I probably would not. But since we do, we did. You can feel the difference, we used the Solar Guys and put a couple in. But if I weren't going to store items in the attic, I probably wouldn't.

These guys are terrific. Trust them.

How many more vents are needed ?
 

Fans at a high point in the roof tend to get air from the easiest source. That would probably be the other closest vents and this will disturb the natural airflow between the soffit vents (lower intake) and upper passive mushroom vents.
Adding more upper exhaust openings should help air flow to lower temps in attic.
The question is how many and where to locate them.
Where do you put them?

I agree, I say they are just vents, no fans in them! I agree that vent fans help but only to a certain degree. As hot as Florida is you would almost need a 3 ft. Chicken coop fan to make it worth while. Those little vent fans MIGHT just maintain the heat up there to a certain degree. So when you get your vent fan installed, go to your attic & come back here & give us your honest evaluation how cool your attic is! I had a 2 ft. vent fan put in our house & personally it was still very hot up there, couldn’t tell it cooled nothing.

I used power vents in the mid-atlantic.

In the summer, that area is as hot as Florida -- just for less time -- maybe 3 - 4 months.

I found that the motors burnt out often and it is a real pain to replace them. Each time a fan burns out, it is somewhere between $40 - $65 to replace the motor. Some of the roof domes are better designed than others -- some require the top to come off and others can be replaced from the inside. Regardless, it always seems they burn hot in the heat and are a miserable affair to replace.

Still, I could not believe it when my neighbor, a former contractor, told me that all our Power Vents were just the domes without any electrical fans. I had never seen them installed unpowered. I don't even think you can buy them withou motors without a special order.

Attic “cooling”
 

Install radiant heat reflective insulation.

I have never heard it. I wonder sometimes if it is even working, lol.

We too used Solar Guys for an electric fan that keeps the garage cooler. It also pushes air through the attic and I'm convinced it keeps the house cooler and reduces utility costs. The fan is 10 years old now and works like a charm.

Attic Fan necessary in North Central Florida
 

Absolutely! Even if it is not efficient in dollars and cents, it will add to the creature comforts we all beg for in August and September.

We had a 110v attic fan up north. Considered one for here and decided I did not want a 110 grounded devise mounted in the roof to attract lighting.

I bought one from Lowes and had a friend install it! It brings the heat from the outside , thru the garage and out through the attic… doesn’t do any good except I can smoke cigars in the garage without stinking up the place!