The Harbor Breeze Solar LED light can be purchased for about $15 and includes a capable solar panel, lithium ion cell and charge controller in a waterproof enclosure. The RAK baseboards fit perfectly inside the solar compartment. Below are the steps for completing this hack for a completely weatherproof solar powered Meshtastic node.
An ipex to sma pigtail is needed if in order to have an external antenna. A JST-PHR-2 connector is required if you want a plug-in type battery connection. Soldered connection will also work though. Sealing glue (silicone or marine sealant)
Step 1. Unscrew 4 small screws to open the solar compartment.
Step 2. Solder your battery JST-PHR-2 connector or power wires to the + and - terminals of the battery. If you don't have the proper connector you can solder directly to the pins on the back of the JST connector, just make sure you get the polarity correct.
Step 3. Drill the hole for your sma pigtail. A perfectly vertical antenna via 90 degree bend will not allow for a very flat solar panel so choose wisely or use an externally mounted antenna. You can skip this step if you want to use an internal antenna that fits.
Here is an amazon link to the sma and antennas : (https://www.amazon.com/gp/product/B0CTXL61LY) NOTE: Some of these antennas perform much worse when in a not straight configuration, so ensure you keep them straight or test them with a NANO VNA.
Here is a 3d printed base for wall mounting just the solar panel and its pivot on a wall without the light (designed by a fan of this project): https://www.thingiverse.com/thing:6839973
Here is a 3d printed wall mount that keeps the antenna in a straight configuration and does not require extra drilling: (https://www.printables.com/model/886187-harbor-breeze-meshtastic-mount)
Here is a 3d printed mount for the smaller RAK 19003 Wisblock board : (https://www.thingiverse.com/thing:6849930)
