I am trying to power my Argons and Xenons with a solar panel and LiPO battery. However, the solar panel is 12V, so we need a charge controller/ battery shield to step it down for the Argon, because the on-board step down regulator is only through the USB and may not be suited for this. Is Argon and Xenon computable with Power Shield? I can only find where Power Shield is comparable with Photon. If not, do you have any suggestions for a charge controller to use?
The Gen3 devices (Argon, Xenon) have feather format pins whereas the Photon does not so that a Power Shield aimed at a Photon will not work.
You could plug in a LiPo battery and then get a step down converter to produce 5V output from the solar panel and then connect this via the micro USB or VUSB and GND.
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Would the legacy converter board work for this?
Re: Classic Adapter: It seems to work. Note the pins overhanging, since the CA is designed to go into an Electron socket.
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@ Armor
Yes, we like your idea of a solar panel with a step down converter to provide a steady 5V to VUSB. The specs for argon or xenon both say 500mA for VUSB. If we are using something like a buck boost converter to provide a steady 5V, then the amps will vary with the amount of sunlight. Is there a way to prevent power flow to VUSB if the amperage drops below 500mA?
And if we cut off the current flow in low light conditions, do we need a to add a heat sink to avoid damaging the solar panel?
Thanks in advance.
Take a look at this thread - many answers to many similar questions 
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I haven’t tried this and @shanevanj project share link from @chipmc is probably your best source of best practice. My thinking was that the solar panel regulator ensures that only 5V is supplied to VUSB - so if the solar panel is not producing it will not provide any voltage on VUSB. But you will have a LiPo battery plugged in so this can step in and power the Argon until there is 5V again on VUSB. I would need to look at the circuit schematic to know whether there is a diode on VUSB to stop reverse current or whether the PMIC does this.
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If you’re not stuck with the 12V panel, you can use a 6V panel and large Li-Po, with no other hardware required for the Argon.
But since the Argon is a hungry device, sticking with a 12V System is a more robust solution for extended cloudy days verses the cost of a very large Li-Po.
This is a general 12V Solar & SLA Combo that I’ve had good luck with in the past for less than $60 USD.
10W Solar Panel, 12V, with charge Controller
Any 12V SLA battery
Any 12V to 5V micro USB
The only physical connection to the Argon is the USB, of course.
If you want the Argon to monitor the 12V battery, you can also add a 5:1 voltage divider like this and sample the 12V SLA battery with an Analog Pin.
Another Add-On is a 12V Timer Relay since you have much more capacity with the SLA than you need, wasting a little doesn’t hurt a thing, $5 timer relay . This will minimize the chance that you will need to travel to the site to Power Cycle the Argon (Borons, in my case) in the future. I use the timer relay as an adjustable external WatchDog and the Particle Device will subscribe to it’s own scheduled WDT Publish Event. If the WDT publish doesn’t make it to the Cloud and Back, the Timer Relay will perform a complete Particle Power-Down with a defined OFF interval. I use 15 seconds without power when something goes wrong with the Cloud Connection. The Timer Relay kills the 12V power path to the 12V:5V USB converter when it times-out from missing 1 (or multiple, you decide) scheduled WDT subscribed events.
This inclusive combo above is a pretty robust solution, if physical size isn’t a concern.
I know this isn’t a direct response to the original question/post, but it might be an alternative worth considering?
Ah! Thank you! This put us on the right track. Definitely saved money too.