# Solar Powered Phone Charger

Discussion in 'General Electronics Discussion' started by WaleLuvr, Aug 29, 2014.

1. ### WaleLuvr

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Aug 29, 2014
I am new to electronics and looking for some help. I have a small solar panel and want to turn it into a portable phone charger. Not sure what i would need and where to connect anything. Looking for someone to completely help me with this build. Any help or advice would be greatly appreciated.

7,682
1,688
Jan 5, 2010
How small.

Bob

3. ### WaleLuvr

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Aug 29, 2014
It is 1.25"x1.25"

4. ### ketanrd01

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Aug 11, 2014
can you check the output voltage of your solar panel using multimeter? I guess a panel of this size cant provide sufficient voltage to charge your cellphone WaleLuvr....

5. ### WaleLuvr

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Aug 29, 2014
I could easily purchase another panel much larger. Could you recommend a size/voltage?

6. ### ketanrd01

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Aug 11, 2014
one providing around 12V. It is much larger WaleLuvr

7. ### ketanrd01

74
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Aug 11, 2014
The size makes it difficult to use as a portable charger but you could make a stationary one

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Aug 29, 2014
Thank you.

9. ### WaleLuvr

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Aug 29, 2014
Is there anyone on here that could help me write the plans to this? Everything I need and how to assemble.

10. ### BobK

7,682
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Jan 5, 2010
How much larger?

Solar panels produce about 150W / square meter.

To charge a cell phone in a reasonable time you are going to need about 1A at 5V = 5W.

So you need 5 / 150 = 0.033 square meters. With is a square of 18cm (7 in).

Your 1.25in panel, if you could make it work efficiently, would take about 30 times as long as a 1A charger would take (say 2 hours.) On a good day, you get about the equivalent of 6 hours of full sun. So maybe 10 days would do it, if it don't rain.

Have fun.

Bob

11. ### WaleLuvr

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Aug 29, 2014
I guess a solar panel that will output that much.

12. ### BobK

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Jan 5, 2010
Yes, and a regulator to 5V, which is what the cell phone will want to see. For efficiency you want to use solar panel that puts out more than 5V, and use a switch mode DC-DC converter to lower the voltage. These can be had on EBay for a couple of bucks.

Bob

13. ### Gryd3

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Jun 25, 2014
You would need a 7" x 7" panel or something with the same surface area to provide 1A at 5V.
This is a requirement to be able to produce a reasonable charge for your phone. Any smaller and you would need to leave you phone plugged in for a few hours to charge.

The only solution to using a smaller panel would be if you built a device that has it's own internal battery and sat in the sunlight all day. Then it would use it's internal battery to power the phone. The kicker here is that that as you decrease the panel size, the charge time increases greatly. You need to collect over 10Watt-hours to provide a full charge for your phone.

14. ### BobK

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Jan 5, 2010
My 7x7 inch calculation was based on 15% efficiency of solar panels. If you look on EBay, the solar phone chargers tend to be a little bigger than this, so probably more like 8x8 inches + a very efficient regulator.

Bpb

15. ### WaleLuvr

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Aug 29, 2014
How many watts should the panel be?

-colin

16. ### Externet

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Aug 24, 2009
Six volts panel should be enough, and cannot find now the ones to adhere in the back of a cell phone. Perhaps discontinued.
The ones I see now are ----> http://www.inhabitat.com/wp-content/uploads/samsungsolarphonewow.jpg
and ----> http://assets.inhabitat.com/wp-content/blogs.dir/1/files/2010/06/samsung-guru2.jpg

The watts will be whatever the size that fits on the phone. Smaller will take longer to recharge.

A clumsily executed ---->

Last edited: Aug 30, 2014
17. ### Gryd3

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Jun 25, 2014
I don't know about you, but I would rather not leave my phone in direct sunlight to charge. It may extend the life of the device

18 Sq Inches on the back of a Samsung Galaxy Note will provide you with 1.8W, which is about 360mA. You would need a good 6 Hours in the sunlight to charge your phone. A 30-minute commute with the phone on the dash will provide less than 8% of a charge.

You know the numbers, you can continue how you see fit.

18. ### WaleLuvr

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Aug 29, 2014
I dont really care how this thing would look. I know what size solar panel i need. What do i need after that?

Last edited: Aug 31, 2014
19. ### WaleLuvr

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Aug 29, 2014
What kind of Power inverter will i need?

20. ### Gryd3

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Jun 25, 2014
Voltage regulation so you can convert the voltage from the panel to 5V for the USB out of the device.
The type of regulator will depend on the voltage you receive from the panel. If the voltage from the panel is higher, get a buck converter. If the voltage is lower, get a boost converter. I have very little experience with these things, so that's all the information I can give right-away