Combining Solar Panels with built in DC-DC converters

Thread Starter

nickbuhling

Joined Oct 27, 2017
28
Thank you for reading my post!

I would like to build a solar charger for a phone/powerbank. I bought 2 of these solar panels which already have DC-DC converters on them. My questions are:
  1. How can I combine their power to make a stronger charger? It seems weird to combine them after the DC-DC converters. Or do I just do that and connect it to a female USB port (since they are glued to the panels)?
  2. If I do connect them together after the DC-DC converters, the voltage will at times with limited sun be around 4.4V. This does not damage the device that is charged, correct?
  3. I assume I don't need flyback diodes if I connect them after the DC-DC converters. Is this correct?

Any suggestions will be highly appreciated! Thank you in advance!
 

Thread Starter

nickbuhling

Joined Oct 27, 2017
28
Connect them all in series before a DC to DC converter
That is a good idea. That does mean I have to try to to pry of the already existing DC to DC converters on both panels and wire the panels in series (with a diode i suppose?) directly to the Step Down DC-DC converter to get 5v. Otherwise it would not be possible to put them in series right, with DC-DC converter in between?

Thanks!
 

mvas

Joined Jun 19, 2017
538
Do think you can actually remove the DC-to-DC Converter module and not damage the panels?
 
Last edited:

pmd34

Joined Feb 22, 2014
503
I would see how the actual output voltage varies with light intensity, from the label on the back it mentions and open circuit voltage of 7.2V .. voltage at Pmax 6.1... this suggest that there actually is no DC-DC converter or regulator built in!
 

Thread Starter

nickbuhling

Joined Oct 27, 2017
28
A DC to DC coverter is not going to drive any current into it’s input. A battery would.

Bob
I see that. But I meant when taking of the DC-DC converters. So when you have the "raw panels" with a + and -. Is a diode necessary in that case? Thanks for your time!
 

Thread Starter

nickbuhling

Joined Oct 27, 2017
28
I would see how the actual output voltage varies with light intensity, from the label on the back it mentions and open circuit voltage of 7.2V .. voltage at Pmax 6.1... this suggest that there actually is no DC-DC converter or regulator built in!
Yes, I think that is info about the panels itself. In the small plastic case, there is a converter, but I managed to take them off and expose the + and -.
 
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