thermostat for 24V DC car fan connected to 200W solar panel

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Scotty
Scotty Registered Users Posts: 2 ✭
in Solar Beginners Corner #1
Hello out there,

I have a 24V DC car fan that I'd like to run with a 200 W solar panel.  The fan is 7.3 amp.  But, I want to wire a thermostat between the two and I haven't been able to find a thermostat that fits this need.  I am using the fan to ventilate a greenhouse.  I could direct wire it the fan to the panel but it would be better if I could turn the fan on at about 80 degrees F.   Is there such a thermostat out there?
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #2
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    You can get 200F thermostats rated for DC in a car cooling fan,  but the small adjustable ones you can get online at Grainger.com are only rated for AC and DC would quickly ruin them   But look there anyway, you may find an AC/DC version
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,044 ✭✭✭✭✭
    #3
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    I purchased some 12 volt automotive fans ( inexpensive on ebay ) to ventilate my garage which I hardwired to a 70 watt solar panel. They work great as the intensity of the sun regulates their speed. They have been running faithfully for a year now.  I only mention this because maybe it would be easier to find a 12 volt thermostat.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • Scotty
    Scotty Registered Users Posts: 2 ✭
    #4
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    Thanks you guys.  I'll work on your suggestions.
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  • animatt
    animatt Solar Expert Posts: 295 ✭✭✭
    #5
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    Not sure if you can find a snap switch with the proper rating. I would think it should be inexpensive.
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  • Brock
    Brock Solar Expert Posts: 639 ✭✭✭✭
    #6
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    I have done a similar setup using a 24vdc relay running off the thermostat.  The relays pull in about 16v, below that and you likely wouldn't want the fan on anyway.  The only catch is in low light it might flip on and off a lot  Or use a 12vdc relay and a small 12v battery to power the relay and run through the thermometer and use the relay between the panel and the fan.
    3kw solar PV, 4 LiFePO4 100a, xw 6048, Honda eu2000i, iota DLS-54-13, Tesla 3, Leaf, Volt, 4 ton horizontal geothermal, grid tied - Green Bay, WI
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  • Shadowcatcher
    Shadowcatcher Solar Expert Posts: 228 ✭✭✭
    #7
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    There are a number of 12DC thermostats from China and while I would be a bit concerned about claimed amps certainly they can drive a relay. I am using one to regulate a 12VDC solar hot water pump and 100MM case fan.
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  • vince
    vince Registered Users Posts: 79 ✭✭
    #8
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    myDTCstore.com has some controllers now that can run off a 12v solar panel and has a mosfet that allows to regulate the speed as a function of the temperature. Just installed one and works great. It can feed a load up to 3A or operate as a relay.
    Sunpower 3 x 435 watt panels, 48 v 215 AH battery bank (Sam's club), Midnite Kid and WBjr, Fujitsu 9RLS3 split duct AC, Outback FX 3048T + transformer 2000W 120/220V, GrapeSolar Fridge.
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