This device is a RAK4630. Its a very low power board. I'll be testing solar soon. 
Discussion
The RAKs are great for solar powered nodes. I’ve got 2 nodes running on solar, each just has a single 18650 battery and I’m using a cheap USB-C solar panel to charge them. Both nodes stayed up on solar for the entire winter here in Australia.
Nice 👌🏽 I like this