Solar trailer getting awfully hot---is this a problem?

Plowman
Plowman Solar Expert Posts: 203 ✭✭✭✭✭
in Solar Beginners Corner #1
I have my little off-grid system (see my signature) installed in/on a small stationary cargo trailer. It gets full sun all day long. I've only been using it in this configuration for a couple months now, temperatures have been pretty mild.

A bit warm today, only around 80F outside, but enough to get the trailer up to ~90F. I'm afraid when we regularly see temps in the 90s this summer the trailer will be an oven. I have my batteries, charge controller, inverter, etc. inside.

Trailer currently has two small vents, but I'm going to add at least two or three more, and maybe enlarge the existing ones.

Also thinking of installing a couple large computer fans on either end of the trailer. Suggestions for thermostats or other ways to only have the fans run when needed? Maybe load diversion on charge controller so it only runs during the day?

Any other suggestions?

Here's an older pic (I've since added a second panel and am in the process of building a new mount big enough for 4 panels):

14191571158_0fb8c041c3_z.jpg

Bad cell phone pic of my redneck interior set up:

14376812152_675f4dc9ab_z.jpg
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Comments

  • zoneblue
    zoneblue Solar Expert Posts: 1,220 ✭✭✭✭
    #2
    Re: Solar trailer getting awfully hot---is this a problem?

    The battery is the main concern. The electronics wont enjoy it but theyll tolerate it.

    Options:
    - passive vents: inlet low, outlet high.
    - ditto fan assisted
    - you can get special high relfectance white paint that will let less of the heat through.
    - line the thing with rfoil or simialr, that stuff reportedly works great on commercial warehouses and cheap and easy to put up.
    - any other cheap insulation you can lay your hands on...

    It doesnt take much of a vent to let the heat out. RVs are the same, they use those roof mounted vents.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


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  • PNjunction
    PNjunction Solar Expert Posts: 762 ✭✭✭
    #3
    Re: Solar trailer getting awfully hot---is this a problem?

    Definitely use the remote temp-sensor accessory on the battery for temperature compensation of the charge voltages.
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  • jcheil
    jcheil Solar Expert Posts: 722 ✭✭✭
    #4
    Re: Solar trailer getting awfully hot---is this a problem?

    http://www.homedepot.com/p/Active-Ventilation-5-Watt-Solar-Powered-Exhaust-Attic-Fan-RBSF-8/204202981

    $62 Home Depot, Has it's own little solar panel and runs when the sun is out. There are others that are more $ and more CFM.
    I have a friend that uses one on his 20' shipping container down here in Florida and it keep it much cooler.
    Off-Grid in Central Florida since 2005, Full-Time since June 2014 | 12 X Sovello 205w panels, 9 X ToPoint 220w panels, 36x ToPoint 225w panels (12,525 watts total) | Custom built single-axis ground mounts | Complete FP2 Outback System: 3 x FM80, 2 x VFX3648, X240 Transformer, FLEXnet-DC, Mate-3, Hub-10, FW500 AC/DC | 24 x Trojan L16RE-B Batteries 1110ah @ 48v | Honda EU7000is Generator and a pile of "other" Generators | Home-Made PVC solar hot water collector | Custom data logging software http://www.somewhatcrookedcamp.com/monitormate.html
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  • jonr
    jonr Solar Expert Posts: 1,386 ✭✭✭✭
    #5
    Re: Solar trailer getting awfully hot---is this a problem?

    I'd add rigid foam to any exterior surfaces that are exposed to the sun and consider creating a vented double wall (where the sun heats the outer layer and then air flows between the two layers to remove the heat).

    I am available for custom hardware/firmware development

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  • Plowman
    Plowman Solar Expert Posts: 203 ✭✭✭✭✭
    #6
    Re: Solar trailer getting awfully hot---is this a problem?
    zoneblue wrote: »
    The battery is the main concern. The electronics wont enjoy it but theyll tolerate it.

    Options:
    - passive vents: inlet low, outlet high.
    - ditto fan assisted
    - you can get special high relfectance white paint that will let less of the heat through.
    - line the thing with rfoil or simialr, that stuff reportedly works great on commercial warehouses and cheap and easy to put up.
    - any other cheap insulation you can lay your hands on...

    It doesnt take much of a vent to let the heat out. RVs are the same, they use those roof mounted vents.
    Come to think of it, I have an RV roof vent, it'd be easy enough to install it on the cargo trailer :)

    Thanks for the other suggestions. Rfoil looks interesting, I'll have to price it out. Also thought about rigid foam. I'd like to insulate it somehow.

    Ventilation is also lacking. It gets wicked condensation in winter (which is why I used the plastic Rubbermaids to cover the components and batteries). Insulating and ventilating should help deal with the condensation problem, too.
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  • Plowman
    Plowman Solar Expert Posts: 203 ✭✭✭✭✭
    #7
    Re: Solar trailer getting awfully hot---is this a problem?

    PNjunction, I'll have to take some temp measurements at the charge controller and batteries to see what the difference is. They're only a couple feet away from each other, but the CC and inverter produce their own heat and I've noticed their enclosure is a bit warmer. Our host says to get a temperature sensor if the difference is >10F.

    Jcheil, that's a cool product. I'll have to keep one of those in mind for a cabin. For my cargo trailer I think I'll cheap out and just use the RV vent I already have on hand. Plus the cargo trailer's roof will be completely covered in solar panels when I'm done, won't be any sun left for a solar-powered roof vent.

    Jonr, you're saying adding rigid foam to the outside? Like it doesn't look redneck enough :p How about the interior, how do you think that would work to help regulate temps?
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  • jonr
    jonr Solar Expert Posts: 1,386 ✭✭✭✭
    #8
    Re: Solar trailer getting awfully hot---is this a problem?

    I think rigid XPS foam on the inside would work too. Think vented box within a vented box such that radiant heat in the outer layer cannot penetrate into the inner box.

    I am available for custom hardware/firmware development

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