Building a Solar-Powered Repeater

Here's the parts list that Austin Mesh came up with as their preferred way to build a solar powered repeater.

This design doesn’t require any soldering or complicated connectors. It also doesn’t require any battery management chips (which often have long shipping lead times and can be hard to get).
For this design the solar panel is connected directly to the battery pack via USB. Then the battery pack is connected to the board via USB.

The Voltaic Systems V25 battery is nice because it is optimized to charge from a solar panel and it is set standard to an “always on” mode which means the battery bank does not shut off after a set amount of time like other battery packs – this is useful as the RAK chip uses very little power and can trick other battery packs into shutting off.

The other really nice thing about the Voltaic pack is than when it drains down completely it shuts down, but then once the solar panel has sufficiently charged it back up it will automatically turn itself back on again. Right now they're testing the V25 battery which has 6,400 mAh, but if we were going to install a node in a very hard-to-reach place we’d probably use the larger V75 19,200 mAh battery.

The RAK radio uses between 100 and 1000 mAh per day, with about 400 mAh per day being average so theoretically the Voltaic V25 could keep the radio working for 16 days without any solar power and the V75 could keep the radio running for 48 days without solar.

The above listing for the Solar Repeater build is actually based on fairly outdated info. However, there are many members experiementing with solar builds on our Matermost Instance and willing to help with any questions or guidnace.
One of our members, @bnova recently put together a nice solar build and has some pictures and an updated listing of parts for a similar Solar Repeater build like the above:

From @bnova:
"So it's a more compact unit with a built in solar panel. In theory less to break in bad weather. Downside is lower battery capacity. I have 7.5ah in mine, but two 5ah lipo cells should fit to give 10ah.
Solar panels charge up to 400ma while the rack unit, if memory serves, charges the batteries at 400ma. During the 5 hours of solar maximum, I'd imagine 2.5ah of capacity is charged not counting for the upward of 1ah of power used through the 24hr period.
It has a plug in the bottom for external power if needed with 3 additional wires for other uses.Overall cost is similar to the listed build on the denvermesh site but offering a different footprint. Possibly less conspicuous and possibly more robust to bad weather. Time will tell how it holds up."