The MQTT letterbox Part 2: Sending alerts from MQTT // Project


Installing the solar panel was easy. I used hot glue for this as I wanted to be able to take it off easily should I need to, and also didn’t want to drill any mounting holes into the letterbox making it less waterproof. Since it was a cold day, I had to pre-heat both the letterbox and ESP box so that the hot glue would stick better to the metal.


Then ran some glue on the edges of the ESP box and held it in place until the glue hardened.

It ended up being fairly secure. I suspect that on a very hot Australian summer it’d melt and fall off, but that’s another 6 months away for me and I have plenty of time to fix it properly.

Next, connect up the panel, and mount the rear flap sensor with a bit of gaff tape.