I have 6kW worth of solar panels on the roof. On nice warm summer days I can mine basically for free for some hours a day. The perfect combo is having double the solar of what you need to mine with and find a good way to store the excess energy to use it during the night. Batteries are the most common solution for this. However I saw a very interesting documentary on storing excess energy with inertia. Very cool stuff.

In any case I have yet to just arrange something with my home automation so that my miners start/stop depending on the watts I produce. Just haven't had time to get to it.