Using a solar panel without a battery

shmuel
shmuel Registered Users Posts: 4
in Solar Beginners Corner #1
I'd like to connect a 19V (max.) solar panel to a female car plug, then plug in a USB car adapter, in order to charge cellphones and the like. Should I attach the female car plug to the load terminals of a charge controller, or are charge controllers meant to be used only with a battery attached?

Any advice would be appreciated.
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  • Rybren
    Rybren Solar Expert Posts: 351 ✭✭
    #2
    Re: Using a solar panel without a battery

    Charge controllers generally need to be connected to a battery for them to work.

    I don't believe that your USB adapter will work properly being connected directly to the PV panel, but I'm sure that our resident experts will chime in soon to correct me if I'm wrong.
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  • shmuel
    shmuel Registered Users Posts: 4
    #3
    Re: Using a solar panel without a battery

    Thanks for your reply.

    So how do I prevent the solar panel, which can get up to 19 volts, from frying the USB car adapter, which excepts 12 volts?
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #4
    Re: Using a solar panel without a battery
    shmuel wrote: »
    How do I prevent the solar panel, which can get up to 19 volts, from frying the USB car adapter, which accepts 12 volts?

    Solar Panel feeds Charge Controller, which in turn feeds Battery, which then feeds USB car adapter.
    Need to know more detail on solar panel before Battery Size and Charge Controller can be suggested.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,642 admin
    #5
    Re: Using a solar panel without a battery

    In theory, this Anker 12 volt 24 watt USB charger runs up to 24 volt input:

    http://www.amazon.com/Anker®-Dual-Port-Charger-PowerIQ-Technology/dp/B00B8M4IMK

    I use it in my car for charging various USB phones/tablets/etc... And so far--I have been very happy with it.

    It is cheap enough that I would try it and see if it works with a direct solar panel input. If it does not, or "blows up"--Not much is lost.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • shmuel
    shmuel Registered Users Posts: 4
    #6
    Re: Using a solar panel without a battery

    Thanks. It looks like a very nice adapter.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,642 admin
    #7
    Re: Using a solar panel without a battery

    One thing to be careful of--Some failures could include allowing 12-24 volts to your USB device... I would use a "cheap" USB device first when experimenting on the rare chance that a USB charger failure could take out the USB load too.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • shmuel
    shmuel Registered Users Posts: 4
    #8
    Re: Using a solar panel without a battery

    OK, thanks. I have a USB doctor I can use to test the output voltage.
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  • AuricTech
    AuricTech Solar Expert Posts: 140 ✭✭
    #9
    Re: Using a solar panel without a battery

    Wouldn't it be easier simply to use a solar panel that is already optimized for USB charging, such as the Goal Zero Nomad series of panels?
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #10
    Re: Using a solar panel without a battery

    I like Bill's idea, Since it will handle 24v you likely won't have a problem, I've used a 6v - 5 watt panel with a simple voltage regulator, to charge USB devices with better than good results. Even my fussy Nokia N800 would charge. Says it will handle up to 35v. You could likely strip a heat sink and a USB female out of an old tower. Since most USB devices for lithium regulate the charging I think this would work fine, even with a larger panel.

    RatShack 5v regulator
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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