Charge phone from two solar panels in (parallel?)

Thread Starter

Drilon

Joined May 20, 2021
1
Hello everyone.
I have two 6v 750mah(each) solar panels and want to charge a phone. I have watched youtube videos but again i dont really know how ir works. I have somehow managed to connect one solar charger with a usb car charger, but it doesnt work and even when it works ir charges the phone really slowly. Can someone help me. Thank you :)
 

DickCappels

Joined Aug 21, 2008
7,426
Welcome to allaboutcircuits.com!

Your USB car charger is probably expecting 12 volts so your solar panels should be in series for the car charger to work.

You may be have a better charging experience by placing 1 amp silicon diodes (for example 1N4001 or higher voltage) in series with each cell then putting the two panel/cell combinations in parallel. The phone will have its own charger internally.

The series diodes have two functions: They prevent a panel in the shade from leaching current from the panel in sunlight and they drop the voltage from 6 volts to 5.3 volts which should be safe for any phone designed to use a USB charger.

By the way, in case it ever matters, 750 mah means your panels can supply 750 ma for an hour (relates to the total amount of energy available), it is probably actually 750 ma (relates to the peak amount of current available).
 

andrewmm

Joined Feb 25, 2011
1,466
Do not put solar panels in parallel
the one that has the higher voltage will back drive the lower voltage one , and at best lowering the life of the second cell.
As @DickCappels says,
put the panels in series,
they could well have diodes on them already, but check, they are needed,
Then have a dcdc to drop the voltage to the one you need, whilst boosting the current you can receive.
 
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