It is tedious and time-consuming, but there is no shortcut around learning and getting experience with new hardware. For the next revisions there is a lot of new tech I want to adopt: I'd like to integrate a SPI-connected TFT screen, add  wireless communication, and separate the controller functions to do onboard solar position calculations on a master controller. To support the development, I created below carrier board so I can work out the required code and exact pin assignments. It is built purely for hardware integration and code development. 

The 2.8" TFT screen is already nicely working on the MKR Zero. Next, I'll switch the TFT over to the Raspberry Pi Zero,  DIP switches can route the TFT display SPI signals to either side. 

The XBee modules I haven't started yet. Three modules are to form a star network, each has a microcontroller attached to it: Raspberry Pi Zero W (left), Arduino MKR Zero (center), and Teensy 3.5 (right). Eventually, they should all talk to each other over the air. There are quite a number of competing wireless communication standards to choose from, I'd love to hear other experiences.

I have got long list of schema improvements accumulating with the increased complexity. The next Suntracker revisions will need some time to built, accommodating the learning curve.