With the problem of lighting resolved, the next issue was how to control everything. It was quickly apparent that there could not be a single central controller that handled every set of lights individually this would take 21 output pins from the microcontroller, and a bundle of cables of the same number, with each cable at least 20awg, you end up with a wire that is likely around 10mm diameter, if you can even buy it! Connecting to this umbilical cord like cable would be problematic at best, as well as running it neatly from point to point.

This didn't even take into account any monitoring I wanted to do on the performance of the solar panel and battery system, or communications to and from the house.

I quickly came to a conclusion that it would be much easier to move to a hierarchical organization. Taking the channel control from a central point and putting it at each point of use meant that I only needed to run 12v power to each point plus whatever communication wiring I needed. This reduced the problem from nearly impossible to very simple.

Once I recognized the need for individual controllers, it became a simple task of specifying a controller to switch 3 channels (to be repeated once for each light) and a controller to overwatch everything. These became known as the "Light Controller" and "Main Controller", with the main controller handling communications to and from the house, and each light controller simply switching the 3 channels for the local light string.