Need to solar charge a single cell lipo to power a moteino + bright led

[pgregg]

I'm helping a friend build a scale model of the solar system on a family ranch in West Texas.

My job is designing planet "nodes". These planet nodes are moteino based nodes driving 1-3 WS8211 "pixel" LEDs using the FastLED library. The LEDs light up a small plexiglass globe (the planet). I'm using outdoor PVC electrical conduit to raise the planet globe high enough to where it can be seen from the "earth" location. The electronics are stored in a watertight PVC electrical box.

The plan is to power these nodes with a single 18650 lipo battery and charge the battery during the day with a 6v solar panel. However, finding a solution to charging the lipo based on the variable voltage of a solar cell has been much more challenging than I anticipated.

I've seen examples of people asking questions about this scenario, but I haven't found a design for a solar "hat".

Who's already solved this one? I'm looking for ideas and options.

Thanks -PG

[TomWS]

I saw these on Digikey and should work for your application (solar cell is separate, however).  Be sure to check the polarity of the LiPo connector, it is not a standard and could be reversed from your battery. 
https://www.digikey.com/products/en?mpart=DFR0264&v=1738

[john4444]

Hi Pgreg,
Adafruit has a nice LiPo charger for solar applications. https://www.adafruit.com/product/390
I have used several of these and they work well, unlike circuits not designed for solar.
Good luck

[pgregg]

Excellent. Thank you TomWS and john4444 for the ideas. I'll check them out.