One of the biggest problem today about the solar panels is the part after the solar cells, so the converter/ regulator. I wanted to write that for have the best performance with the solar cells for a smartphone / battery.

What do you need:

3x Solar Panels They are 6v/ 6w but in my opinion more about 5w. 3 because they can produce around 15v(5v x 3) so it's the closet of the 12v required for the QC 3.0.
A car Cigarette lighter "charger"
A QC 3.0 Charger

Total Cost (with 3 Solar Panels) = 26.50€

If you don't have wires & soldering parts:

20 Awg wires
Tabbing wire(you can also use the normal 20awg wire)
An usb soldering iron (you don't need more)
Solder wire (like 0.5mm)

I choose to use a Cigarette Lighter Socket + QC Charger because at the moment we can't find QC 3.0 modules, we find them only in the Car chargers.

So lets go

Step 1: Create Holes, It's Just for Attach the 3 Solar Panels

Step 2: Solder the Panels

Solder the panel, for increase the voltage like here, we have to connect like that:

(-) panel1 (+) ------ (-) panel2 (+) ----- (-) panel3 (+) if you want to increase only the current you have to connect the (-) with the (-) and the (+) with the (+). But voltage will stay at 5v so the QC 3.0 will not work.

Step 3: Solder the (-) and (+) to the Cigarette Socket.

Step 4: Test It !

I use the new Xiaomi 20 000mAh power bank 2 (QC 3.0) with a low capacity (2/4 charing bar).

Around 10W !
When i made that picture the sun started to drew low, it was 20h14 and the panels were not super clean there was a little of dust on them. 20h14 is bad for the solar power, so it's a really good result! You can add more power by adding a solar panel in parrallele for exemple so you will need 6 panels (because we have to add a second panel for the 3 or the parrallel system will not works). But the QC is limited to 1.5A at 12v so it's overpowered.

Original from my Blog

Edit: during 1 day, i stuck the panels to a window(inside) and during the day(from 10am to 6pm) it recharged the Xiaomi battery around 65%, it's around 50Wh so 13,5 Ah.