Solar panels and electrical vehicles become more and more common in Switzerland. Ten years ago I installed solar panels. To use the available solar energy, the electrical vehicle charging box has been augmented with an open source charge controller. The controller monitors the building energy usage and adjusts the current using the Modbus connection to the charger.
Outline
With such a charger, the charger can direct surplus solar energy to the vehicle instead to the grid, increasing self-consumption of the energy and saving money: currently I have to pay more than 40 cents for 1 kWh, and I get less then 9 if I feed it to the grid.
To charge the vehicle, I’m using a 11 kW wallbox from Heidelberg, the Energy Control: This wallbox can be controlled by a RS-485/Modbus protocol.
The controller communicates with MQTT with the building using Home Assistant. See Controlling an EV Charger with Modbus RTU for the hardware and software.
So far the electronics was external in its own enclosure. Finally I have integrated it into the wallbox. Here is how I did it….
Wallbox
The wallbox power electronics are inside that box:
The box indicates its status with the 6 LED visible in the picture above. The over on top of it is a PMMA\Acrylic sheet which easily can be replaced with a custom design:
I decided to replace it with a clear 4 mm PMMA version, because I want to show the internals and the same time use the front window with the color LED as status indicator. To cut and engrave it, I used a laser cutter.
The engraving is on the back, to have a smooth front side:
This then gets placed behind the front cover:
There is a 10 mm space between the electronics box and the front: I placed the PCB with a 3D printed back enclosure on front of the electronics box, fixed with zip ties:
The PCB snaps into the black 3D printed piece.
The white wallbox LEDs shine from the back, and the controller module provides status with 4 RGB LEDs plus the OLED display:
It is hard to take good pictures of it, but I think it looks really cool :-). It is a useful extension to the wallbox, an makes it special at the same time.
Happy charging 🙂
MCU on Eclipse 