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Making a solar cell phone charger

  1. Feb 11, 2015 #1
    Good day everyone,

    So I have a spare solar panel that has been laying around and I want to put it to use. Its a small panel, about 8"X12". The specs read 8 Watts and 17 Volts

    I was thinking of maybe making a solar charger for phones and other 5VDC USB devices.

    I bought a 5VDC regulator kit, soldered it together and got it to work with the panel
    This is the kit:

    Next I want to hook the output up to a set of maybe 2 or 4 USB ports. I can get these off an old computer or other device.

    My question is, how do I know how much current this thing will output at 5VDC?
    I know my factory cell phone charger outputs 2000ma or 2 amps.
    How do I know that this setup will not output more than that and damage the device being charged.
    Or is this setup even strong enough to go up to 2 amps?

    Is there a way to test for this?

    Thank you and sorry for the long post

  2. jcsd
  3. Feb 11, 2015 #2


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  4. Feb 11, 2015 #3
    I had not thought about charging a battery pack. That might be better, it is not limited to providing power only while under the sun.

    I will look at these examples in detail tonight when I get home

    Thank you!
  5. Feb 12, 2015 #4


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    The specifications for the PV is; 17V, 8W. The current will be ( 8W / 17V ) = 0.47A.
    The regulator is a linear regulator so Iin = Iout.
    The maximum current out will therefore be 470 mA.

    The voltage drop across the regulator will be 17Vin – 5Vout = 12V
    The regulator will therefore dissipate power ( 12V * 0.47A ) = 5.64W
    Maybe you should consider a heatsink if the regulator gets hot.
  6. Feb 18, 2015 #5
    The regulator chip did did begin to get a little hot so I did attach a small heatsink to it.
    I am using it to charge a portable phone charger that itself is charged with 5V

    Seems to work just fine now.

    Thank you!
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