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Minty Boost + Flexible Solar panels
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Minty Boost + Flexible Solar panels

by jacobh11 on Mon Dec 02, 2013 11:42 pm

Hello,
I have just purchased the necessary components for creating a solar charger using mintyboost and usb/dc and solar lipoly charger. My goal is to create a desktop sculpture that uses 4 of the flexible solar panels from adafruit (6V 1W) connected in series? so that I can charge my iphone 5. Will wiring 4 flexible panels together in series result in in a power rating of 6V 4W? If this is the case, do I need to add a resistor to adjust the max charge current? As the solar charger tutorial says it can support panels up to 3 W:

"The USB/Solar charger comes with a preset rate of 500mA which will work great for USB ports, USB wall adapters and solar panels up to 3 Watts. If you have a project that uses a larger panel, or perhaps some other sort of setup, you can easily adjust the current by soldering a resistor into the PROG pads"

I am also wondering if you can give advice as to best practices, and best wiring to use for connecting the flexible solar panels together in series (not parallel, correct?).

My last question pertains to the batter pack. I have purchased a Lithium Ion Polymer Battery - 3.7v 2500mAh. Given my desired end product, how does this battery differ from the other batteries with higher amperage?


Thanks for any insight!

jacobh11
 
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Re: Minty Boost + Flexible Solar panels

by adafruit_support_bill on Tue Dec 03, 2013 6:58 am

A few issues:

* Wiring panels in series will add the voltages, not the current. If you want more current at the same voltage, you need to wire them in parallel. The maximum voltage input for the charger is 6v, so you want a parallel configuration.
* The 6v/1W rating is for panels outdoors, exposed to full sunlight. A desktop location is likely to output only a small fraction of that power.
* When wiring panels in series or in parallel, it is generally a good idea to use bypass or blocking diodes to prevent damage or loss of efficiency if one or more panels becomes shaded relative to the others.

My last question pertains to the batter pack. I have purchased a Lithium Ion Polymer Battery - 3.7v 2500mAh. Given my desired end product, how does this battery differ from the other batteries with higher amperage?

A battery with a higher mAh capacity will be able to store more energy if it is available. You would need to do some experimentation to see how much power your panels can actually generate in the location you intend to install it.

adafruit_support_bill
 
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Joined: Sat Feb 07, 2009 10:11 am

Re: Minty Boost + Flexible Solar panels

by jacobh11 on Wed Dec 04, 2013 5:23 pm

Hello,
Thank you for the quick reply!
I am hoping you can help me clarify a few more things:

- I have also purchased a large 6V 3.7W panel to help supply more power for the desktop positioning. If I wire this large panel in parallel with my 4 flexible panels the idealized output would be 6V, 7.7W. Does this 7.7W output thus require a resistor to be soldered onto the PROG pads as pointed out in the solar charger tutorial:

"The USB/Solar charger comes with a preset rate of 500mA which will work great for USB ports, USB wall adapters and solar panels up to 3 Watts. If you have a project that uses a larger panel, or perhaps some other sort of setup, you can easily adjust the current by soldering a resistor into the PROG pads"

Would this PROG pads resistor be different than the bypass or blocking resistors you mention here?:

adafruit_support_bill wrote:* When wiring panels in series or in parallel, it is generally a good idea to use bypass or blocking resistors to prevent damage or loss of efficiency if one or more panels becomes shaded relative to the others.


-Where/how would I incorporate bypass or blocking resistors into the setup that I am describing?
-Does Adafruit sell these resistors?
-How would I choose the proper resistors?

Sorry for all of the questions, but I am truly a beginner in electronics.

Thanks again, Jacob

jacobh11
 
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Joined: Mon Dec 02, 2013 10:43 pm

Re: Minty Boost + Flexible Solar panels

by adafruit_support_bill on Wed Dec 04, 2013 5:52 pm

Does this 7.7W output thus require a resistor to be soldered onto the PROG pads as pointed out in the solar charger tutorial:

It is not required, but since your 2500mAh cell can handle the higher charge rate, it will allow faster charging when solar conditions permit.

Would this PROG pads resistor be different than the bypass or blocking resistors you mention here?:

Sorry, my bad. I meant to say bypass and/or blocking diodes. I've edited my post to correct that. See this page for a diagram and explanation of bypass and blocking diodes: http://www.mysolarpannels.com/solar-panel-diode/

adafruit_support_bill
 
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Joined: Sat Feb 07, 2009 10:11 am

Please be positive and constructive with your questions and comments.