Incredibly, the hut we are working from actually had another solar panel just laying around. 🙂
This 50w square panel had a junction box with MC4 connectors, the standard for small scale solar installations. As I was unsure how to know when we are running low on electricity reserves, I decided to make some adjustments.
(Everything is still solder, hot glue, alligator clips, and zip-ties I’m afraid…)
I traded my NEMA / USA two-prong connection with two MC4 splitters, such that both panels can run in parallel (into a standard USA 110v extension cord that goes into our hut). This way we should make well over one of the two 35ah batteries-worth of electricity a day.
I also added a cheap 12v battery level indicator. It is not very accurate (as it fluctuates with solar input) but it does give us some insight about how much "juice" we have available. (I also wired and glued the remote-on switch to the back of the input for stability.)