FWIW, for the build2 project we host our own CI servers on premesis and the power supply is supplemented by a solar array. We have configured our daily package

FWIW, for the build2 project we host our own CI servers on premesis and the power supply is supplemented by a solar array. We have configured our daily package rebuild window to coincide with the maximum solar output so that on a sunny day it is all done using renewable energy.