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Solar Powered Roof Vent for Cargo Trailer  

Updated 07/30/2025 | Published 06/04/2022

Question:

I would like to use this fan to help exhaust heat from a small cargo trailer, only 350 cu ft volume. I like this unit because it is low profile and can be used regardless of weather. I really only need it to function well when the trailer is in direct sun which really heats up the inside. Would it be possible to hardwire this fan to a 30 watt solar panel that would be mounted to the roof adjacent to the fan? If the fan is 12V and 2 Amp draw that is 24 watt if my math is close. A 30 watt panel mounted flat would not ever reach full output so seems safe. Regardless, I can work out the solar panel compatibility. But this way, as soon as the panel was in direct sun it would power the fan on, if the switch was left in the on position, and when shaded it would shut off. Is there a problem you can see with this logic?

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Expert Reply:

I have a solution for you, it is a smaller fan unit but we have an item that will function in the way you are looking for. The MaxxFan Mini Plus Manual RV Roof Vent, # MA00-03851 that you linked to needs a fairly stable power supply of 12 VDC and draws slightly less than 2 amps to operate. Wiring directly to solar panel will not support this as the power will fluctuate greatly and eventually damage the electronics in the in the fan. To operate, you need a stable 12 VDC power supply from either a power grid or from a battery bank.

The Ultra-Fab Solar-Powered Plumbing Vent for Motor Homes, # UF53-945001 is a smaller fan with the units overall dimension being only 7" in diameter. However, you can install more than one if you choose too and it will operate in the way you are wanting it to.

The MaxxFan Mini Plus Manual RV Roof Vent, # MA00-03851 will move more air but you will need a solar panel, a solar controller, battery and associated wiring and fuses. I also recommend that you have a low voltage shut off between the fan unit and the battery to protect the battery from deep discharge.

I also recommend that you add a side vent to help with air flow, something such as the 2-Piece Polypropylene Trailer Vent for 3" Diameter Hole, # HMAV2-AVT2 for black or, # WHMAV2-WAVT2 for white. And then we also have a metal vent option with the 2-Piece Side Vent for Enclosed Trailers, # 9139.

expert reply by:
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Michael R
Brian W. profile picture

Brian W.

7/3/2025

Powered Roof Vent for Cargo Trailer Looking for something along the same lines, but 120Vac to plug in while parked at home. Even better if it fits in the same space as the unpowered vent.

Kate F. profile picture
Etrailer Expert

Kate F.

7/3/2025

@BrianW The only 120V Vent/fan that we have is the Ventline Roof Vent w/ 120V Fan - Manual Lift - 14-1/4" x 14-1/4" - White - Polar Trim # V2128SP-01. What kind of system do you have going on? Do you hook up to shore power, or strictly boondocking?
Brian W. profile picture

Brian W.

7/3/2025

@KateF 2007, 6' x 10' Haulin by Forest River CARGO trailer that I use for giant scale R/C warbirds (80 inch or greater wingspan model airplanes). I need to keep the radios in the planes below 105 degrees. I have 120Vac available in my driveway that I can plug into when parked. I would also like to obtain a spare wheel hub for roadside emergencies. Thanks!
Kate F. profile picture
Etrailer Expert

Kate F.

7/7/2025

@BrianW I'm afraid that a little roof vent like that won't keep it cool enough, it would just help vent the hot air out. In order to keep if cool enough have you thought about a portable cooler, or fan that you just just plug in and place inside, then install some 2-Piece Exterior Wall Vent for Enclosed Trailers - Powder Coated Steel - 10" x 12" # 9139 to let the hot air escape? I am not sure where you are located, and how hot it gets. If you want to do a full wiring set-up, let me know and I will get a parts list for you to run electric. As for a spare wheel, I do not have a database that supplies me with what is put on what trailers. In my research I am showing that most of them come equipped with the 205/75/r15 with a 5 on 4 1/2" bolt pattern, in that case the Kenda Karrier ST205/75R15 Trailer Tire with Black Mod Wheel - 5 on 4-1/2 # AM32424 would be a great spare. My Dad used to take us to go watch his buddies fly their planes out in the middle of the desert when I was a kid, those model planes are super cool!
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